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Wearable Activity Monitors in Home Based Exercise Therapy for Patients with Intermittent Claudication: A Systematic Review

  • Calvin Chan
    Affiliations
    Department of Surgery and Cancer, Imperial College London, London, UK
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  • Viknesh Sounderajah
    Correspondence
    Corresponding author. Department of Surgery and Cancer, St Mary’s Hospital, 10th floor Queen Elizabeth Queen Mother building, Praed Street, London, W2 1NY, UK.
    Affiliations
    Department of Surgery and Cancer, Imperial College London, London, UK

    Institute of Global Health Innovation, Imperial College London, London, UK

    Imperial Vascular Unit, Imperial College Healthcare NHS Trust, London, UK
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  • Pasha Normahani
    Affiliations
    Department of Surgery and Cancer, Imperial College London, London, UK

    Imperial Vascular Unit, Imperial College Healthcare NHS Trust, London, UK
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  • Amish Acharya
    Affiliations
    Department of Surgery and Cancer, Imperial College London, London, UK

    Institute of Global Health Innovation, Imperial College London, London, UK

    Imperial Vascular Unit, Imperial College Healthcare NHS Trust, London, UK
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  • Sheraz R. Markar
    Affiliations
    Department of Surgery and Cancer, Imperial College London, London, UK
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  • Ara Darzi
    Affiliations
    Department of Surgery and Cancer, Imperial College London, London, UK

    Institute of Global Health Innovation, Imperial College London, London, UK
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  • Colin Bicknell
    Affiliations
    Department of Surgery and Cancer, Imperial College London, London, UK

    Institute of Global Health Innovation, Imperial College London, London, UK

    Imperial Vascular Unit, Imperial College Healthcare NHS Trust, London, UK
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  • Celia Riga
    Affiliations
    Department of Surgery and Cancer, Imperial College London, London, UK

    Institute of Global Health Innovation, Imperial College London, London, UK

    Imperial Vascular Unit, Imperial College Healthcare NHS Trust, London, UK
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Open ArchivePublished:January 12, 2021DOI:https://doi.org/10.1016/j.ejvs.2020.11.044

      Objective

      Intermittent claudication (IC) can severely limit functional capacity and quality of life. Supervised exercise therapy is the recommended first line management; however, this is often limited by accessibility, compliance and cost. As such, there has been an increased interest in the use of wearable activity monitors (WAMs) in home based telemonitoring exercise programmes for claudicants. This review aims to evaluate the efficacy of WAM as a feedback and monitoring tool in home based exercise programmes for patients with IC.

      Data Sources

      A search strategy was devised. The databases MEDLINE, EMBASE, and Web of Science were searched through to April 2020.

      Review Methods

      Randomised trials and prospective trials were included. Eligible trials had to incorporate WAMs as a feedback tool to target walking/exercise behaviour. The primary outcome was the change in walking ability. Study quality was assessed with risk of bias tool.

      Results

      A total of 1148 records were retrieved. Of these, eight randomised controlled trials and one prospective cohort study, all of which compared a WAM intervention against standard care and/or supervised exercise, met the inclusion criteria. Owing to heterogeneity between studies, no meta-analysis was conducted. WAM interventions improved measures of walking ability (heterogeneous outcomes such as maximum walking distance, claudication distance and six minute walk distance), increased daily walking activity (steps/day), cardiovascular metrics (maximum oxygen consumption), and quality of life.

      Conclusion

      There is some evidence that home based WAM interventions are beneficial for improving walking ability and quality of life in patients with IC. However, existing studies are limited by inadequate sample size, duration, and appropriate power. Achieving consensus on outcome reporting and study methods, as well as maximising device adherence, is needed.

      Keywords

      This review provides an evaluation of home based exercise interventions incorporating wearable activity monitors as a feedback and monitoring devices on walking ability and behaviour in patients with intermittent claudication. Wearable technology interventions improved measures of walking ability and behaviour and may be a feasible alternative to supervised exercise and improve patient access and lower costs. However, there needs to be consensus over study outcome measures and solutions in achieving greater adherence.

      Introduction

      Peripheral arterial disease (PAD) of the lower extremities is a progressive atherosclerotic occlusive pathology that often presents with intermittent claudication (IC), defined as lower limb pain or discomfort induced by walking and relieved by rest.
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      IC causes patients to suffer from significant walking impairment, loss of functional status, and poor quality of life (QoL).
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      Worryingly, the prevalence of PAD in people aged 25 and over is estimated to be 5.56% globally and the incidence is rising.
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      Recommended first line management for patients with IC includes supervised exercise therapy (SET), risk factor modification, and drug therapy.
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      2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the European Society for Vascular Surgery (ESVS): document covering atherosclerotic disease of extracranial carotid and vertebral, mesenteric, renal, upper and lower extremity arteries endorsed by: the European Stroke Organization (ESO), the task force for the diagnosis and treatment of peripheral arterial diseases of the European Society of Cardiology (ESC) and of the European Society for Vascular Surgery (ESVS).
      SET has been shown to improve walking distance and QoL for claudicants.
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      Exercise for intermittent claudication.
      ,
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      The effect of supervised exercise, home based exercise and endovascular revascularisation on physical activity in patients with intermittent claudication: a network meta-analysis.
      A typical programme generally consists of 30–60 minutes of intermittent treadmill walking in a supervised clinical setting in up to three sessions per week for three to six months.
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      ,

      NICE. Peripheral arterial disease: diagnosis and management. Available at: https://www.nice.org.uk/guidance/cg147 [Accessed 22 June 2020].

      However, a number of limitations to SET exist, such as cost, poor patient compliance, lack of availability, lack of sustainability, and poor patient engagement with physical activity following completion of the programme.
      • Harwood A.E.
      • Smith G.E.
      • Cayton T.
      • Broadbent E.
      • Chetter I.C.
      A systematic review of the uptake and adherence rates to supervised exercise programs in patients with intermittent claudication.
      • Makris G.C.
      • Lattimer C.R.
      • Lavida A.
      • Geroulakos G.
      Availability of supervised exercise programs and the role of structured home-based exercise in peripheral arterial disease.
      • Shalhoub J.
      • Hamish M.
      • Davies A.H.
      Supervised exercise for intermittent claudication – an under-utilised tool.
      As such, there has been increased interest in home based exercise programmes (HEPs), which involve structured patient managed walking in the community setting, as a potential alternative to SET.
      • Al-Jundi W.
      • Madbak K.
      • Beard J.D.
      • Nawaz S.
      • Tew G.A.
      Systematic review of home-based exercise programmes for individuals with intermittent claudication.
      It is thought that lower costs and the ease of home exercise may improve patient acceptability. In order to increase the effectiveness of home based exercise interventions, behaviour change techniques, such as self monitoring and performance feedback, have also been studied.
      • Galea M.N.
      • Weinman J.A.
      • White C.
      • Bearne L.M.
      Do behaviour-change techniques contribute to the effectiveness of exercise therapy in patients with intermittent claudication? A systematic review.
      This has stimulated interest in the use of commercially available wearable activity monitors (WAMs) as part of a home based exercise intervention for patients with IC. WAMs (e.g., FitBit, Garmin, or Polar) are typically accelerometer or pedometer based devices worn on the wrist in order detect the wearer’s movement and activity. In comparison to traditional methods of tracking activity (i.e., a self reported activity log), WAMs allow accurate, autonomous long term tracking, and quantification of physical activity (e.g., daily steps, walking distance, heart rate).
      • Brickwood K.J.
      • Watson G.
      • O’Brien J.
      • Williams A.D.
      Consumer-based wearable activity trackers increase physical activity participation: systematic review and meta-analysis.
      WAM devices can be further differentiated into “smart” (i.e., with the ability to communicate with smartphone or computer applications to provide a range of feedback and motivational tools) or “classic” devices (i.e., the device only displays basic activity data).
      • Lyons E.J.
      • Lewis Z.H.
      • Mayrsohn B.G.
      • Rowland J.L.
      Behavior change techniques implemented in electronic lifestyle activity monitors: a systematic content analysis.
      In studies involving non-IC patient populations, improvements in exercise behaviour have been noted with WAM based exercise.
      • Cadmus-Bertram L.A.
      • Marcus B.H.
      • Patterson R.E.
      • Parker B.A.
      • Morey B.L.
      Randomized trial of a Fitbit-based physical activity intervention for women.
      • Lyons E.J.
      • Swartz M.C.
      • Lewis Z.H.
      • Martinez E.
      • Jennings K.
      Feasibility and acceptability of a wearable technology physical activity intervention with telephone counseling for mid-aged and older adults: a randomized controlled pilot trial.
      • Frederix I.
      • Driessche N Van
      • Hansen D.
      • Berger J.
      • Bonne K.
      • Alders T.
      • et al.
      Increasing the medium-term clinical benefits of hospital-based cardiac rehabilitation by physical activity telemonitoring in coronary artery disease patients.
      • Luley C.
      • Blaik A.
      • Götz A.
      • Kicherer F.
      • Kropf S.
      • Isermann B.
      • et al.
      Weight loss by telemonitoring of nutrition and physical activity in patients with metabolic syndrome for 1 year.
      • Kirk M.A.
      • Amiri M.
      • Pirbaglou M.
      • Ritvo P.
      Wearable technology and physical activity behavior change in adults with chronic cardiometabolic disease: a systematic review and meta-analysis.
      Thus, this systematic review aimed to evaluate the effectiveness of WAMs as part of a home based intervention to improve walking ability, walking behaviour, and QoL in patients with IC.

      Materials and methods

      Eligibility criteria

      This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.
      • Moher D.
      • Liberati A.
      • Tetzlaff J.
      • Altman D.G.
      • Group T.P.
      Preferred reporting items for Systematic Reviews and Meta-Analyses: the PRISMA statement.
      Randomised controlled trials, crossover trials, and prospective studies utilising a WAM were included. All study intervention groups received treatment incorporating a WAM that was used for feedback purposes to target walking or exercise behaviour (i.e., to set or change the exercise prescription and to monitor adherence). Trials that used WAMs solely as a tool to measure pre–post outcomes were excluded as they did not use the device as a behavioural intervention. Inclusion of trials was not affected by participant number, duration of intervention programmes, or the type of WAM device used.
      Studies that recruited participants >18 years of age with symptomatic IC due to PAD were included. Further inclusion criteria consisted of objective measures of PAD such as ankle brachial pressure index <0.90, duplex ultrasound scan, or baseline treadmill tests as well as clinical history.

      Search

      Following PRISMA recommendations, an electronic database search was conducted using MEDLINE, Embase, and Web of Science to include articles up to April 2020 written in English (search strategy detailed as part of the Supplementary text). Reference lists were examined from the retrieved full text articles. ClinicalTrials.gov was searched for in progress trials. Search terms included both MeSH/Emtree terms and keywords with proximity and wildcard operators for the two concepts of the review: the disease (e.g., Intermittent Claudication/, peripheral arterial disease, leg adj3 occlus∗) and the intervention (e.g., Wearable Electronic Devices/, wearable∗ adj3 step∗).
      Search results were then imported into Covidence (Covidence.org, Melbourne) for duplicate removal and study selection. Screening and data extraction were performed independently by two investigators (C.C. and V.S.). Conference abstracts and protocol papers were excluded. Full text articles were then reviewed, and data collected on the methods, participants, intervention, outcomes, and findings. Disagreements were resolved through discussion.

      Outcomes

      The primary outcome was change in walking ability. This outcome was quantified by several different methods. Pre–post intervention treadmill tests (i.e., Gardner graded treadmill test or constant load treadmill test) produced measures of maximum walking ability (MWA, i.e., peak/maximum walking distance) and pain free walking ability (PFWA, i.e., claudication onset time, claudication distance). Walking ability was also quantified with the six minute walk test.
      • McDermott M.M.
      • Guralnik J.M.
      • Criqui M.H.
      • Liu K.
      • Kibbe M.R.
      • Ferrucci L.
      Six-minute walk is a better outcome measure than treadmill walking tests in therapeutic trials of patients with peripheral artery disease.
      The secondary outcomes were changes in daily walking activity (DWA, i.e., change in steps/day), QoL (measured through patient questionnaires), and cardiovascular metrics (e.g., oxygen consumption [peak VO2]).

      Risk of bias

      Bias was assessed using either the Revised Cochrane Risk-of-Bias Tool for Randomised Trials (RoB 2)
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      • Elbers R.G.
      • Blencowe N.S.
      • Boutron I.
      • et al.
      RoB 2: a revised tool for assessing risk of bias in randomised trials.
      or Risk of Bias in Non-randomised Studies of Interventions (ROBINS-I).
      • Sterne J.A.C.
      • Hernán M.A.
      • Reeves B.C.
      • Savović J.
      • Berkman N.D.
      • Viswanathan M.
      • et al.
      ROBINS-I: a tool for assessing risk of bias in non-randomised studies of interventions.
      Risk of bias was assessed across five domains independently by two investigators (C.C. and V.S.) and disagreement settled by discussion. Risk of bias in each domain was graded as low, some concerns, or high.

      Results

      Search

      A literature search yielded eight randomised controlled trials and one prospective study that met the study inclusion criteria which were included for review. Details of the search results can be found in Fig. 1.
      Figure 1
      Figure 1Preferred reporting items for Systematic Reviews and Meta-Analysis (PRISMA) flow diagram showing the process of study selection for this systematic review of wearable activity monitors as a feedback tool to target walking/exercise behaviour in intermittent claudication.
      Heterogeneity in outcome measures used to quantify maximum walking ability (i.e., maximum walking distance, peak walking time, six minute walk) and pain free walking ability (i.e., claudication distance, claudication onset time, functional claudication distance) precluded meta-analysis.

      Characteristics of included studies

      Study design

      Characteristics of included studies can be found in Table 1. Study duration ranged from six weeks
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      to 12 months.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      Study population ranged from 20
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      to 304 patients.
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      Six studies were conducted in the United States,
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      ,
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      ,
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      two in the United Kingdom
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      ,
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      and one in The Netherlands.
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      Two studies were multicentre and had a large participation number of 200
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      and 304
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      respectively.
      Table 1Characteristics of the 9 studies included in the systematic review on wearable activity monitors (WAM) as a feedback tool to target walking/exercise behaviour in intermittent claudication
      First author (year)Study designParticipantsInterventionWAM usedOther interventions or controlOutcome measures
      Normahani (2018)
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      12 mo RCTn = 37, mean age 69.1, 81% M, symptomatic ICWAM + SET (1 h/w). Clinic consultation at 3, 6, and 12 mo to discuss daily walking goalsNike+ FuelBandSET (1 h/w for 3 mo)MWA + PFWA (constant-load treadmill test), QoL (VascuQol)
      Endicott (2019)
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      6 mo prospective studyn = 49, mean age 67.4, 98% M, veteran population, symptomatic ICWAM based exercise prescription. Clinic consultation every 4 w to discuss step count and goalsFitBit OneN/ADWA
      Duscha (2018)
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      12 w RCTn = 20, mean age 69.4, 84.2% M, mean ABPI 0.62, symptomatic ICWAM based HEP exercise prescription with electronic IC info and weekly telephone consultationsFitBit chargeUsual careMWA + PFWA (Gardner graded treadmill test) and DWA
      McDermott (2018)
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      9 mo RCT (multicentre)n = 200, mean age 70.3, 47.5% M, mean ABPI 0.664 SET sessions in 1st month then HEP + WAM with weekly telephone consultationsFitBit ZipUsual care6 min walk test, DWA and QoL (SF-36 + PROMIS)
      Gardner (2011)
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      12 w RCTn = 119, mean age 65, 48% M, mean ABPI 0.73, symptomatic ICWAM used during HEP sessions 3×/w. Duration increased from 15 to 40 min/session. 15 min consultation every 2 wStepWatch3(1) SET (3×/w for 3 mo)

      (2) Usual care
      MWA + PFWA (Gardner graded treadmill test) and QoL (SF-36)
      Gardner (2014)
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      12 w RCTn = 180, mean age 65, 53.3% M, mean ABPI 0.70, symptomatic ICWAM with HEP sessions 3×/w. Feedback given on data at 1, 4, 8, and 12 w. Duration increased from 20 to 45 min. 15 min consultation every 2 wStepWatch3(1) SET (3×/w for 3 mo). Duration increased from 20 to 45 min

      (2) Light resistance training (3×/w)
      MWA + PFWA (Gardner graded treadmill test), 6 min walk test and cardiovascular metrics (ischaemic window, LAEI/SAEI, StO2, hsCRP)
      Nicolaï (2010)
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      12 mo RCT (multicentre)n = 304, mean age 66.2, 63.1% M, mean ABPI 0.66, symptomatic ICWAM + SET (60-–90 min/w). WAM score used during physiotherapy sessions to give feedback on walking effort outside SETPam Personal Activity Monitor(1) SET (30 min 2–3×/w) + WA + told to walk to maximum pain 9×/d

      (2) WA + told to walk to maximum pain 9×/d
      MWA + PFWA (Gardner graded treadmill test) and QoL (SF-36)
      Mays (2015)
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      14 w RCTn = 25, mean age 65.4, 80% M, mean ABPI 0.81, symptomatic IC or previous endovascular therapy2 w SET (3×/w) then 12 w HEP (3×/w) with WAM and weekly telephone consultationsPiezoelectric activity monitor (OrthoCare Innovations) and Accusplit AE120XLUsual careMWA + PFWA (Gardner graded treadmill test) and QoL (SF-36)
      Tew (2015)
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      6 w RCTn = 23, mean age 68.6, 69.5% M, mean ABPI 0.66, symptomatic ICStructured IC education (PREMIS) + WAM based walking self regulation to build step count to >7500/d. Telephone consultation at 2 wYamax SW-200 DigiwalkerUsual careMWA + PFWA (Gardner graded treadmill test), 6 min walk test and QoL (EuroQol EQ-5D-5L)
      ABPI = ankle brachial pressure index; BASIC = Baltimore Activity Scale for Intermittent Claudication; DWA = daily walking activity; HEP = home based exercise programme; LAEI/SAEI = large artery elasticity index/small artery elasticity index; M = male; MWA = maximum walking ability; QoL = quality of life; PFWA = pain free walking ability; PROMIS = Patient-Reported Outcomes Measurement Information System; PRWA = patient reported walking ability; RCT = randomised controlled trial; SET = supervised exercise therapy; WA = walking advice; WAM = wearable activity monitor; WELCH = Walking Estimated-Limitation Calculated by History; WIQ = Walking Impairment Questionnaire.

      Participants

      All studies included participants with symptomatic IC. However, one study
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      also included patients who received endovascular therapy four to six weeks before baseline testing alongside patients with stable symptomatic IC. One study had an exclusively veteran population.
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      All studies included participants of both genders with the proportion of males from 47.5%
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      to 98%.
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      Patients were excluded from studies if they had any co-morbidities that limited exercise or required mobility aids.

      Intervention

      Four study interventions included SET in conjunction with a home based exercise prescription with WAM.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      ,
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      ,
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      ,
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      Of these four studies, two studies
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      ,
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      began the intervention with SET then transitioned to HEP with WAM for the remainder of the duration (four weekly SET sessions then eight months HEP and two weeks SET then 12 weeks HEP with WAM, respectively). There were also different frequencies and modes of follow up during studies. Five studies
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      ,
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      had regular follow up in person consultations with physicians, research staff, or physiotherapists for monitoring progress, adjusting exercise prescription dose, and downloading WAM data. The four other studies contacted patients by telephone for the same purposes for the duration of the intervention.

      Devices used

      Eight different WAMs were used in the included studies (Table 1) and fit into two broad categories: triaxial accelerometers and pedometers. In terms of newer technology, six triaxial accelerometers were used in seven studies. FitBit devices were the most popular and three models were used in three studies: the FitBit One,
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      FitBit Charge,
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      and FitBit Zip.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      Other triaxial accelerometers used were the Nike+ FuelBand,
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      StepWatch 3,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      and Personal Activity Monitor.
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      Two pedometers were used to monitor physical activity in two studies: the Accusplit AE120XL
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      and Yamax SW-200 Digiwalker.
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      Two interventions required patients to use a smartphone or tablet to synchronise their WAM data online.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      ,
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      If patients did not have a smart device at home, they were provided with one.

      Control

      One study compared a WAM intervention and a SET control (one hour/week for three months).
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      Three studies
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      were three pronged and compared a home based WAM intervention against SET and usual care or an alternative (e.g., light resistance training
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      ). The remaining studies
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      ,
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      compared a WAM intervention against usual care, which typically consisted of physician advice and printed information leaflets.

      Outcomes

      Regarding walking ability, seven studies assessed MWA and PFWA. These were measured by several techniques: six studies used the Gardner graded treadmill test,
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      ,
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      ,
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      and one study used a constant load treadmill test.
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      The six minute walk test was used in three studies.
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      ,
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      Change in daily walking activity was measured in six studies. Four studies evaluated steps/day,
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      ,
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      and two studies measured maximum ambulatory cadence.
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      Seven studies assessed QoL. Five studies used Short-Form 36.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      ,
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      VascuQol, PROMIS and EuroQol EQ-5D-5L were also used.
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      ,
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      ,
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      Finally, concerning cardiovascular metrics, three studies measured changes in peak VO2, which is the maximum rate of oxygen consumption during exercise.
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      One study measured ankle systolic blood pressures obtained before and after treadmill testing and calf muscle StO2 (i.e., tissue muscle oxygen saturation) via near infrared spectroscopy.
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.

      Risk of bias

      An overview of the risk of bias assessment can be found in Fig. 2. One study was assessed to raise “some concerns” due to possible bias in randomisation and allocation as these processes were not disclosed.
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      One study was assessed to have “high risk” of deviation bias as issues with WAM adherence led to alterations in the analysis.
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      Another study was assessed to have “high risk” of selection bias due to non-reporting of patient questionnaire data.
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      The single prospective study
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      was assessed to have a “low risk” of bias (Fig. 3).
      Figure 2
      Figure 2Risk of bias summary: authors’ judgements about each domain of bias for included randomised controlled trials on wearable activity monitors as a feedback tool to target walking/exercise behaviour in intermittent claudication. + = low risk; ? = some concerns; – = high risk.
      Figure 3
      Figure 3Risk of bias summary: authors’ judgements about each domain of bias for included prospective studies on wearable activity monitors as a feedback tool to target walking/exercise behaviour in intermittent claudication. + = low risk; ? = some concerns; – = high risk.

      Effect of interventions on outcomes

      Walking ability

      Seven studies evaluated the efficacy of WAM interventions in improving MWA and PFWA using a treadmill walking test (Table 2). In terms of MWA, five studies demonstrated significant increases vs. baseline and usual care in the WAM intervention groups.
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      ,
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      ,
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      This included three large (n = 119, 180, and 304) studies.
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      Another small study found a significant increase in peak walking time compared with baseline, although this change was not significant compared with the usual care group.
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      Finally, one small pilot study (n = 25) found no significant change in peak walking time vs. baseline.
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      Table 2Study results regarding walking ability in a systematic review of wearable activity monitors (WAMs) in intermittent claudication
      First author (year)Outcome measure – unitFollow up momentWAM interventionUsual careSupervised exercise therapy
      BaselineFollow upBaselineFollow upp valueBaselineFollow upp value
      Normahani (2018)
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      MWD – m3 mo80 (50–117)112 (91–210)
      Significant change from baseline.
      68 (50–70)80 (50–91).78
      6 mo178 (133–270)
      Significant change from baseline.
      80 (50–91).009
      12 mo147 (131–405)
      Significant change from baseline.
      68 (51–104).011
      CD – m3 mo40 (24–61)54 (41–88)
      Significant change from baseline.
      36 (26–41)36 (26–41).32
      6 mo115 (60–162)
      Significant change from baseline.
      45 (33–85).002
      12 mo110 (57–198)
      Significant change from baseline.
      45 (33–85).011
      Duscha (2018)
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      PWT – s12 w596±271824±309
      Significant change from baseline.
      546±394568±368Ns
      COT – s12 w320±226525±252
      Significant change from baseline.
      252±256231±196≤.05
      McDermott (2018)
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      6MWT – m9 mo330.5±100.2333.4±115.1336.2±96.6348.2±98.1Ns
      Gardner (2011)
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      PWT – s12 w402±285526±374
      Significant change from baseline.
      505±216494±240≤.050325±169540±281
      Significant change from baseline.
      Ns
      COT – s12 w204±137337±250
      Significant change from baseline.
      225±157209±168≤.050196±144361±264
      Significant change from baseline.
      Ns
      Gardner (2014)
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      PWT – s12 w380±274490±350
      Significant change from baseline.
      464±237486±260≤.050356±222547±299
      Significant change from baseline.
      ≤.050
      COT – s12 w195±171300±242
      Significant change from baseline.
      205±167222±180≤.050193±150363±292
      Significant change from baseline.
      Ns
      6MWT – m12 w328±108372±119
      Significant change from baseline.
      376±73380±81≤.050326±94341±87
      Significant change from baseline.
      ≤.050
      Nicolaï (2010)
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      MWD – m12 mo260 (165–370)600 (435–1 040)
      Significant change from baseline.
      260 (160–370)400 (230–490)
      Significant change from baseline.
      <.001
      FCD – m12 mo150 (95–245)460 (295–720)
      Significant change from baseline.
      150 (100–220)320 (180–500)
      Significant change from baseline.
      <.001
      Mays (2015)
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      PWT – min14 w10.1±1.812.4±1.98.2±1.78.2±1.9.037
      COT – min14 w5.8±1.57.4±1.64.7±1.44.1±1.5.045
      Tew (2015)
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      MWD – m6 w585±322655±308375±299323±253
      CD – m6 w143±121164±135138±14299 ±93
      6MWT – m6 w367.3±94.3390.2±93.9355.3±82.7334.6±77.6
      Data are presented as mean ± standard deviation or median (interquartile range). The p value columns indicate significance of changes between WAM interventions and usual care or supervised exercise therapy. All available exact p values are provided where possible. 6MWT = six minute walk test; CD = claudication distance; COT = claudication onset time; FCD = functional claudication distance; MWD = maximum walking distance; Ns = not significant; PWT = peak walking time.
      Significant change from baseline.
      Compared with SET interventions, one pilot study found that a WAM intervention produced significant improvements in MWA at six and 12 month follow up compared with a standard three month course of SET, although there was no significant difference at the three month follow up.
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      However, in terms of studies that compared a WAM intervention with a SET intervention of the same duration, three studies did not find any significant difference in improvement in MWA between WAM and SET interventions.
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      Six studies identified significant improvements in PFWA using WAM compared with baseline and usual care.
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      ,
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      This included three large (n = 119, 180, and 304) studies.
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      Compared with SET, one pilot study found significant improvement in claudication distance at six and 12 month follow up vs. a standard three month course of SET, although there was no significant difference between the two groups at three month follow up.
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      Three other studies that compared a home based WAM intervention with a SET intervention found no significant difference in PFWA.
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      The findings of three studies evaluating walking ability with the six minute walk test were conflicting (Table 2). Two studies (n = 23 and 180) demonstrated significant improvement in six minute walk distance vs. baseline and control.
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      Contrastingly, a larger scale multicentre study (n = 200) by McDermott and colleagues found no improvement in six minute walk distance with WAM intervention compared with usual care or baseline.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.

      Daily walking activity

      Four studies evaluated changes in steps/day (Table 3).
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      ,
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      Three RCTs did not identify any significant increases in steps/day vs. usual care or baseline with WAM interventions.
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      One prospective study found a significant increase in steps/day for the duration of the study in patients who used the WAM for at least one month.
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      Both studies by Gardner and colleagues
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      found significant increases in maximum ambulatory cadence vs. baseline and control, which suggested patients were walking more briskly during home based exercise sessions with a WAM intervention. Additionally, the larger scale multicentre study (n = 200) by McDermott and colleagues found significant increases in exercise frequency at three and six month follow up in the nine month intervention duration, although there was no significant increase in steps/day.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      Table 3Daily walking activity in a systematic review of wearable activity monitors (WAM) in intermittent claudication
      First author (year)Outcome measureFollow up momentWAM interventionUsual careSupervised exercise therapy
      BaselineFollow upBaselineFollow uppBaselineFollow upp
      Endicott (2019)
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      Steps/d6 mo3 492 (2 661–4 322)4 502 (3 636–5 367)
      Indicates significant change from baseline.
      Duscha (2018)
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      Steps/d12 w6 829 ± 3 3707 121 ± 3 3175 011 ± 1 8225 048 ± 2 074Ns
      McDermott (2018)
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      Exercise frequency3 mo1.7 ± 2.93.7 ± 2.51.5 ± 2.12.2 ± 3.0.005
      6 mo4.3 ± 6.82.4 ± 3.5.045
      9 mo3.5 ± 4.22.3 ± 2.9.09
      Steps/d4.5 mo3 945 ± 2 6893 744 ± 2 698
      9 mo3 551 ± 293
      Gardner (2011)
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      Max 60 min cadence strides/min12 w10.4 ± 5.212.9 ± 7.8
      Indicates significant change from baseline.
      12.4 ± 4.911.1 ± 4.0≤.0509.2 ± 3.09.3 ± 3.3Ns
      Gardner (2014)
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      Max 60 min cadence strides/min12 w9.8 ± 4.711.9 ± 6.6
      Indicates significant change from baseline.
      12.3 ± 5.211.7 ± 4.8≤.0509.6 ± 3.810.3 ± 4.5Ns
      Tew (2015)
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      Steps/d6 w5 915 ± 3 7795 538 ± 2 8644 765 ± 2 5394 271 ± 2 261
      Data are presented as mean ± standard deviation or median (interquartile range). The p value columns indicate significance of changes between WAM interventions and usual care or supervised exercise therapy. All available exact p values are provided where possible. Ns = not significant.
      Indicates significant change from baseline.

      Quality of life

      Six studies evaluated QoL via patient questionnaires (Table 4). Five studies reported significant improvement in QoL metrics, particularly in the physical function category vs. baseline and control.
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      ,
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      ,
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      ,
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      However, the larger scale multicentre study (n = 200) by McDermott and colleagues found no change in SF-36 physical functioning score and a decrease in PROMIS reported metrics (pain interference, role satisfaction and mobility) in the intervention group vs. baseline.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      Table 4Quality of life in a systematic review of wearable activity monitors (WAMs) in intermittent claudication
      First author (Year)Outcome measureFollow up momentWAM interventionUsual careSupervised exercise therapy
      BaselineFollow upBaselineFollow uppBaselineFollow upp
      Normahani (2018)
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      VascuQOL3 mo4.7 (3.9–5.2)5.4 (5.2–5.7)
      Indicates significant change from baseline.
      4.5 (2.8–5.0)3.48 (2.4–5.2).004
      6 mo5.6 (5.1–5.8)
      Indicates significant change from baseline.
      4.7 (3.0–5.5)
      Indicates significant change from baseline.
      .031
      12 mo5.8 (5.1–6.0)
      Indicates significant change from baseline.
      3.3 (2.6–4.2).065
      McDermott (2018)
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      SF-369 mo35.8 ± 9.436.5 ± 10.836.939.09.6.24
      Pain interference
      Constituents of Patient-Reported Outcomes Measurement Information System (PROMIS); higher is better.
      9 mo56.4 ± 8.456.9 ± 9.056.7 ± 7.553.4 ± 8.8.002
      Role satisfaction
      Constituents of Patient-Reported Outcomes Measurement Information System (PROMIS); higher is better.
      9 mo48.5 ± 9.948.2 ± 9.748.8 ± 10.450.4 ± 10.3.20
      Mobility
      Constituents of Patient-Reported Outcomes Measurement Information System (PROMIS); higher is better.
      9 mo33.3 ± 5.333.0 ± 6.333.8 ± 5.333.1 ± 5.9.47
      Gardner (2011)
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      SF-3612 w40 ± 2248 ± 23
      Indicates significant change from baseline.
      55 ± 1954 ± 18Ns37 ± 1746 ± 21
      Indicates significant change from baseline.
      Ns
      Nicolaï (2010)
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      SF-3612 mo52.8 ± 14.365.1 ± 16.8
      Indicates significant change from baseline.
      52.4 ± 15.059.0 ± 19.0
      Indicates significant change from baseline.
      .004
      Mays (2015)
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      SF-3614 w42.3 ± 2.845.2 ± 2.038.9 ± 2.840.7 ± 2.0Ns
      Tew (2015)
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.
      ICQ6 w32.7 ± 16.524.7 ± 9.744.8 ± 18.143.3 ± 18.9
      EQ-5D6 w0.7 ± 0.20.8 ± 0.10.5 ± 0.20.6 ± 0.2
      Data are presented as mean ± standard deviation or median (interquartile range). The p value columns indicate significance of changes between WAM interventions and usual care or supervised exercise therapy. All available exact p values are provided where possible. EQ-5D = EuroQol 5-dimension (5L) health status questionnaire (1=full health, 0=death); ICQ = intermittent claudication questionnaire (0 to 100, 0 best); Ns = no significance; SF-36 = Medical Outcomes Study Short-Form 36-item questionnaire physical functioning score (0 to 100, 1000 best).
      Indicates significant change from baseline.
      Constituents of Patient-Reported Outcomes Measurement Information System (PROMIS); higher is better.

      Cardiovascular metrics

      Three studies reported on peak VO2 and results varied (Table 5). One pilot study found a significant increase in peak VO2 vs. usual care and baseline.
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      Another larger study found a significant increase in peak VO2 compared with control only and there was no significant change to baseline or SET.
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      In contrast, one study found no significant difference in peak VO2 against baseline testing or usual care.
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      Other cardiovascular metrics were assessed by one large, three pronged study only.
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      Findings included significant improvements in ischaemic window, high sensitivity C reactive protein, calf StO2 recovery time, and larger artery elasticity index post-intervention vs. baseline. However, there was no significant difference in these metrics post-intervention compared with SET.
      Table 5Cardiovascular metrics in a systematic review of wearable activity monitors (WAMs) in intermittent claudication
      First author (year)Outcome measure – unitFollow up momentWAM interventionUsual careSupervised exercise therapy
      BaselineFollow upBaselineFollow uppBaselineFollow upp
      Duscha (2018)
      • Duscha B.D.
      • Piner L.W.
      • Patel M.P.
      • Crawford L.E.
      • Jones W.S.
      • Patel M.R.
      • et al.
      Effects of a 12-week mHealth program on functional capacity and physical activity in patients with peripheral artery disease.
      Peak VO2 – mL/kg/min12 w15.2±4.2718.0±4.8
      Indicates significant change from baseline.
      14.3±5.414.5±5.7≤.050
      Gardner (2011)
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Scott K.J.
      • Blevins S.M.
      Efficacy of quantified home-based exercise and supervised exercise in patients with intermittent claudication: a randomized controlled trial.
      Peak VO2 – mL/kg/min12 w11.8±3.812.4±3.813.7±3.712.8±3.5
      Indicates significant change from baseline.
      ≤.05011.4±2.511.7±2.9Ns
      Gardner (2014)
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      Ischaemic window – AUC/m12 w–0.72±0.97–0.47±0.78
      Indicates significant change from baseline.
      –0.63±1.54–0.52±0.65Ns–0.59±0.74–0.51±0.94Ns
      LAEI – mL/mmHg × 1012 w14.0±6.416.2±8.7
      Indicates significant change from baseline.
      13.1±4.013.5±4.4Ns12.2±5.512.9±7.2Ns
      hs-CRP mg/L12 w7.68±19.725.86±11.605.91±5.965.32±3.87Ns5.70±6.395.38±5.78Ns
      Time to min calf StO2 – s12 w195±247341±259
      Indicates significant change from baseline.
      245±283272±236≤.010166±196308±275
      Indicates significant change from baseline.
      Ns
      Calf StO2 recovery half time – s12 w168±18492±94
      Indicates significant change from baseline.
      145±149141±145≤.010165±14794±76
      Indicates significant change from baseline.
      Ns
      Mays (2015)
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      Peak VO2 – mL/kg/min14 w17.5±1.318.7±1.315.0±1.315.7±1.3.66
      Data are presented as mean ± standard deviation. The p value columns indicate significance of changes between WAM interventions and usual care or supervised exercise therapy. All available exact p values are provided where possible. hs-CRP = high sensitivity C reactive protein; LAEI = large artery elasticity index; Ns = no significance; StO2 = tissue oxygen saturation; VO2 oxygen consumption.
      Indicates significant change from baseline.

      Discussion

      Although the current existing evidence is limited to mostly small scale trials and as such there is insufficient evidence to draw definitive conclusions, there is some evidence to suggest that home based WAM interventions have a positive effect on improving walking ability, walking activity, QoL, and cardiovascular metrics in patients with IC.
      Although current management for patients with IC advocates supervised exercise therapy, real world adherence and uptake rates are low. Moreover, it may not be widely accessible or suitable for all patients.
      • Harwood A.E.
      • Smith G.E.
      • Cayton T.
      • Broadbent E.
      • Chetter I.C.
      A systematic review of the uptake and adherence rates to supervised exercise programs in patients with intermittent claudication.
      • Makris G.C.
      • Lattimer C.R.
      • Lavida A.
      • Geroulakos G.
      Availability of supervised exercise programs and the role of structured home-based exercise in peripheral arterial disease.
      • Shalhoub J.
      • Hamish M.
      • Davies A.H.
      Supervised exercise for intermittent claudication – an under-utilised tool.
      As such, home based WAM interventions may pose a suitable alternative. Although cost effectiveness of WAM interventions was not evaluated in this review, WAM interventions may be a more economically accessible option compared with SET. In addition to patient travel time and costs, a three month SET programme is estimated to cost between £235 and £345 per patient and requires specialist staff, equipment and room hire,
      • Bermingham S.L.
      • Sparrow K.
      • Mullis R.
      • Fox M.
      • Shearman C.
      • Bradbury A.
      • et al.
      The cost-effectiveness of supervised exercise for the treatment of intermittent claudication.
      an accurate triaxial accelerometer WAM can cost as little as £21. Additionally, WAMs allow individual tailoring of exercise prescriptions that cannot be achieved in group supervised exercise classes.
      However, WAMs do not inherently increase physical activity. Interventions with activity monitors that do not incorporate behaviour changing techniques provide additional information or support to increase physical activity, or specifically target physical activity goals are not effective in increasing physical activity levels.
      • Flores Mateo G.
      • Granado-Font E.
      • Ferré-Grau C.
      • Montaña-Carreras X.
      Mobile phone apps to promote weight loss and increase physical activity: a systematic review and meta-analysis.
      ,
      • Finkelstein E.A.
      • Haaland B.A.
      • Bilger M.
      • Sahasranaman A.
      • Sloan R.A.
      • Nang E.E.K.
      • et al.
      Effectiveness of activity trackers with and without incentives to increase physical activity (TRIPPA): a randomised controlled trial.
      A combination of behaviour changing techniques and WAM interventions may be effective. Mays and colleagues used a three pronged home based WAM intervention consisting of training, monitoring, and coaching.
      • Mays R.J.
      • Hiatt W.R.
      • Casserly I.P.
      • Rogers R.K.
      • Main D.S.
      • Kohrt W.M.
      • et al.
      Community-based walking exercise for peripheral artery disease: an exploratory pilot study.
      WAMs were worn during exercise and data evaluated during weekly telephone follow ups as part of the monitoring component. Coaching consisted of an audit of a patient’s local area to identify suitable walking areas and educational prints and material. Furthermore, Tew and colleagues developed a specialised programme underpinned by a framework of health behaviour theories delivered in conjunction with WAM based self regulated exercise.
      • Tew G.A.
      • Humphreys L.
      • Crank H.
      • Hewitt C.
      • Nawaz S.
      • Al-Jundi W.
      • et al.
      The development and pilot randomised controlled trial of a group education programme for promoting walking in people with intermittent claudication.

      Limitations and future directions

      First, overall risk of bias was variable amongst included studies. Several deficiencies noted in the risk of bias assessment in three of the nine studies (Figure 2, Figure 3) may temper the findings of this review. In particular, two of the larger studies in this review (Gardner et al., n = 180;
      • Gardner A.W.
      • Parker D.E.
      • Montgomery P.S.
      • Blevins S.M.
      Step-monitored home exercise improves ambulation, vascular function, and inflammation in symptomatic patients with peripheral artery disease: a randomized controlled trial.
      Nicolai et al., n = 304),
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      were judged to have high risk deficiencies in reporting of stated outcomes and intervention deviations, respectively.
      Second, the strength of conclusions drawn in this review was limited by the lack of standardised testing methods and reporting of outcomes for exercise interventions in the included studies. Walking ability was measured using either a treadmill test or a six minute walk test. The merits and shortcomings of both methods have been discussed previously.
      • McDermott M.M.
      • Guralnik J.M.
      • Criqui M.H.
      • Liu K.
      • Kibbe M.R.
      • Ferrucci L.
      Six-minute walk is a better outcome measure than treadmill walking tests in therapeutic trials of patients with peripheral artery disease.
      ,
      • Hiatt W.R.
      • Kevin R.R.
      • Brass E.P.
      The treadmill is a better functional test than the 6-minute walk test in therapeutic trials of patients with peripheral artery disease.
      ,
      • Le Faucheur A.
      • de Müllenheim P.-Y.
      • Mahé G.
      Letter by Le Faucheur et al regarding articles, “Six-minute walk is a better outcome measure than treadmill walking tests in therapeutic trials of patients with peripheral artery disease” and “The treadmill is a better functional test than the 6-minute walk test in therapeutic trials of patients with peripheral artery disease”.
      Outcomes from these two tests, the six minute walking distance, and maximum treadmill walking distance, respectively, are not interchangeable and therefore prevents comparison or meta-analysis. McDermott and colleagues recently demonstrated that participants with IC randomised to control/placebo (i.e., no interventions) decreased in six minute walk distance but significantly increased in maximum treadmill walking distance at the six month follow up.
      • McDermott M.M.
      • Guralnik J.M.
      • Tian L.
      • Zhao L.
      • Polonsky T.S.
      • Kibbe M.R.
      • et al.
      Comparing 6-minute walk versus treadmill walking distance as outcomes in randomized trials of peripheral artery disease.
      Thus, this phenomenon of patient familiarity towards treadmill testing, used in seven of the included studies, may have overestimated the effect of WAM interventions to increase pain free walking distance in daily life. With two different non-interchangeable outcome measures commonly being used in assessing exercise interventions in PAD patients, achieving consensus and standardising outcome measures to determine the efficacy of exercise interventions and allow comparison across studies is of the highest priority. This has been highlighted previously in the recently published American Heart Association scientific statement on optimal exercise programmes for patients with PAD.
      • Treat-Jacobson D.
      • McDermott M.M.
      • Bronas U.G.
      • Campia U.
      • Collins T.C.
      • Criqui M.H.
      • et al.
      Optimal exercise programs for patients with peripheral artery disease: a scientific statement from the American Heart Association.
      Third, current evidence is limited in timespan; long term functional outcomes of home based WAM interventions need to be investigated to ascertain the impact of ongoing coaching and intervention sustainability. The longest study in this review was 12 months, and the shortest was just six weeks. Evidence regarding medium to long term follow up is inconsistent. Contrary to the other studies in this review, the larger scale multicentre study by McDermott and colleagues found no improvement in the six minute walk distance at nine month follow up, possibly due to the infrequency of telephone coaching (one call per month in last five months of the nine month study) or loss of participant interest.
      • McDermott M.M.
      • Spring B.
      • Berger J.S.
      • Treat-Jacobson D.
      • Conte M.S.
      • Creager M.A.
      • et al.
      Effect of a home-based exercise intervention of wearable technology and telephone coaching on walking performance in peripheral artery disease: the HONOR randomized clinical trial.
      This was reflected in the plateau in exercise frequency in the last four months of the study, despite significant increases at three and six month follow up. Normahani and colleagues observed a similar trend in performance after six months of WAM use.
      • Normahani P.
      • Kwasnicki R.
      • Bicknell C.
      • Allen L.
      • Jenkins M.P.
      • Gibbs R.
      • et al.
      Wearable sensor technology efficacy in peripheral vascular disease (wSTEP): a randomized controlled trial.
      Issues with long term adherence to treatment and treatment benefit are highlighted by findings that patients with IC have been observed previously to lose all improvements in walking ability six months after completing a six month SET programme.
      • McDermott M.M.
      • Kibbe M.R.
      • Guralnik J.M.
      • Ferrucci L.
      • Criqui M.H.
      • Domanchuk K.
      • et al.
      Durability of benefits from supervised treadmill exercise in people with peripheral artery disease.
      Therefore, longer follow up is needed to investigate whether home based WAM interventions are sustainable in producing continued physiological changes and walking improvements.
      In studies included in this review, WAM adherence, as well as the lack of adherence reporting, was a limitation. Endicott and colleagues found a high rate of WAM non-use (43% did not use FitBit for more than one month) due to device loss or participant loss of interest.
      • Kirk M.A.
      • Amiri M.
      • Pirbaglou M.
      • Ritvo P.
      Wearable technology and physical activity behavior change in adults with chronic cardiometabolic disease: a systematic review and meta-analysis.
      Eighty per cent of dropouts from another study was also due to lack of interest.
      • Endicott K.M.
      • Hynes C.F.
      • Amdur R.
      • Macsata R.
      A modified activity protocol for claudication.
      Nicolai reported that 28.9% of WAM intervention patients only used their device for part of the study year or not at all.
      • Nicolaï S.P.A.
      • Teijink J.A.W.
      • Prins M.H.
      Exercise therapy in peripheral arterial disease SG. Multicenter randomized clinical trial of supervised exercise therapy with or without feedback versus walking advice for intermittent claudication.
      Challenges in patient compliance will hinder the transition from randomised controlled trials to clinical implementation. Several studies did not report adherence or missing WAM data, which suggests that there is a need for further studies to report and assess long term adherence to WAM interventions. Additionally, as uptake and compliance to SET is already low, the question remains whether the factors which drive patient non-adherence to SET intersect with the factors that negatively impact WAM usage in home based exercise.
      • Harwood A.E.
      • Smith G.E.
      • Cayton T.
      • Broadbent E.
      • Chetter I.C.
      A systematic review of the uptake and adherence rates to supervised exercise programs in patients with intermittent claudication.
      ,
      • Aherne T.M.
      • Kheirelseid E.A.H.
      • Boland M.
      • Carr S.
      • Al-Zabi T.
      • Bashar K.
      • et al.
      Supervised exercise therapy in the management of peripheral arterial disease – an assessment of compliance.
      Identification of specific enablers and barriers to compliance has not yet been conducted and is an important direction for future investigation.
      Loss of interest and therefore low compliance to WAMs may also be confounded by lack of digital literacy. PAD primarily manifests in older patients, who have the lowest rates of smartphone adoption and digital literacy.
      • Berenguer A.
      • Goncalves J.
      • Hosio S.
      • Ferreira D.
      • Anagnostopoulos T.
      • Kostakos V.
      Are Smartphones Ubiquitous? An in-depth survey of smartphone adoption by seniors.
      This may be brought about by factors such as lack of knowledge, visual impairment, or lack of interest.
      • Mohadisdudis H.M.
      • Ali N.M.
      A study of smartphone usage and barriers among the elderly.
      To address patient concerns with WAMs and therefore increase compliance, future research needs to assess digital literacy in PAD patients. This could be accomplished at baseline in future home based WAM studies using validated questionnaires such as eHEALS or MDPQ-16.
      • Roque N.A.
      • Boot W.R.
      A new tool for assessing mobile device proficiency in older adults: the Mobile Device Proficiency Questionnaire.
      ,
      • Van Der Vaart R.
      • Van Deursen A.J.
      • Drossaert C.H.C.
      • Taal E.
      • Van Dijk J.A.
      • Van De Laar M.A.
      Does the eHealth literacy scale (eHEALS) measure what it intends to measure? Validation of a Dutch version of the eHEALS in two adult populations.
      With respect to WAM devices themselves, in comparison to “classic” WAM devices (e.g., StepWatch 3 or Yamax Digiwalker), “smart” WAM devices (e.g., Nike Fuelband) are capable of wireless communication with smartphone applications and may be utilised as a behaviour changing medium utilising the principles of “gamification”, the incorporation of elements of game design (i.e., rewards, goals and competition), to increase user engagement to exercise.
      • Lister C.
      • West J.H.
      • Cannon B.
      • Sax T.
      • Brodegard D.
      Just a fad? Gamification in health and fitness apps.
      This opens opportunities for the development of companion mobile applications that utilise gamification to increase exercise behaviour.
      • Zhao Z.
      • Ali Etemad S.
      • Arya A.
      Gamification of exercise and fitness using wearable activity trackers.
      ,
      • Gawley R.
      • Morrow C.
      • Chan H.
      • Lindsay R.
      BitRun: gamification of health data from Fitbit® activity trackers BT.
      These applications could potentially serve as an additional patient motivational tool in settings in which frequent telephone check ups and coaching is not possible.
      Although outside the scope of this review, smartphone applications utilising the built in accelerometers of modern smartphones are also currently being investigated as a PAD home exercise monitoring tool. Ata and colleagues are currently conducting a two year PAD physical activity study completely through an in house iOS smartphone application “VascTrac”.
      • Ata R.
      • Gandhi N.
      • Rasmussen H.
      • El-Gabalawy O.
      • Agrawal A.
      • Kongara S.
      • et al.
      IP225 VascTrac: a study of peripheral artery disease via smartphones to improve remote disease monitoring and postoperative surveillance.
      The application both passively records daily walking activity and also provides biweekly prompts to participants to perform a six minute walk test, allowing frequent, personal monitoring of walking ability. Similarly, Apple recently announced a landmark iPhone/Apple Watch based study in partnership with the American Heart Association and Brigham and Women’s Hospital. The Apple Heart and Movement Study aims to investigate relationships between exercise and mobility habits and cardiovascular health.

      Apple. Apple announces three groundbreaking health studies. Available at: https://www.apple.com/newsroom/2019/09/apple-announces-three-groundbreaking-health-studies/ [Accessed 22 June 2020].

      The near ubiquitous nature of Apple mobile devices lends the possibility of larger scale data collection from specific disease populations, including PAD. However, as of this review, data have yet to emerge from the above studies.

      Conclusion

      There is some evidence that home based WAM interventions may be beneficial for improving walking ability and QoL in patients with IC, therefore potentially improving access to exercise therapy. Further standardisation and creation of a set of guidelines outlining best practice for home based WAM exercise studies, including outcome and duration, is needed for comparison across studies. Further work on reporting and improving device adherence, through assessment of digital literacy or coaching frequency, is necessary to increase intervention effectiveness.

      Conflicts of interest

      None.

      Funding

      Infrastructure support for this research was provided by the NIHR Imperial Biomedical Research Centre (BRC).

      Acknowledgements

      We would like to thank Jacqueline Kemp for her assistance in creating the search strategy.

      Appendix A. Supplementary data

      The following is the Supplementary data to this article:

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