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Editor's Choice – Systematic Review and Meta-Analysis of the Effect of Weekend Admission on Outcomes for Ruptured Abdominal Aortic Aneurysms: A Call for an Equitable Seven Day Vascular Service

  • Robert J. Leatherby
    Affiliations
    Department of Vascular & Endovascular Surgery, The Royal Oldham Hospital, Pennine Acute Hospitals NHS Trust, Northern Care Alliance NHS Group, Manchester, UK
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  • Madison R. Shan
    Affiliations
    Department of Medicine, Tameside Hospital, Tameside and Glossop NHS Foundation Trust, Manchester, UK
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  • George A. Antoniou
    Correspondence
    Corresponding author. Room G37, Vascular Offices, J Block, The Royal Oldham Hospital, Rochdale Road, OL1 2JH, Oldham, UK.
    Affiliations
    Department of Vascular & Endovascular Surgery, The Royal Oldham Hospital, Pennine Acute Hospitals NHS Trust, Northern Care Alliance NHS Group, Manchester, UK

    Division of Cardiovascular Sciences, School of Medical Sciences, The University of Manchester, Manchester, UK
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Open ArchivePublished:February 22, 2021DOI:https://doi.org/10.1016/j.ejvs.2020.12.022

      Objective

      “The weekend effect” of higher patient mortality when presenting at a weekend compared with a weekday has been established for several conditions. The aim of this study was to investigate whether a weekend effect exists for the emergency condition of ruptured abdominal aortic aneurysm.

      Data sources

      A review of the literature was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines (PROSPERO registration number CRD42020157484). MEDLINE, EMBASE and CINAHL were searched using the Healthcare Databases Advanced Search interface developed by NICE.

      Review methods

      The prognostic factor of interest was weekend admission. The primary outcome of interest was all cause peri-operative mortality, with a secondary outcome of hospital length of stay. A random effects meta-analysis was performed, and the results were reported as summary odds ratio (OR) and 95% confidence interval (CI).

      Results

      Twelve observational cohort studies published between 2001 and 2019 comprising 14 patient cohorts with a total of 95 856 patients were eligible for quantitative synthesis. Patients presenting on a weekend had a significantly higher risk of unadjusted in hospital mortality (OR 1.20, 95% CI 1.10 – 1.31, p < .001). Both the unadjusted 30 day mortality risk (OR 1.16, 95% CI 0.98 – 1.39, p = .090) and unadjusted 90 day mortality risk (OR 1.12, 95% CI 0.90 – 1.40, p = .30) were higher for those presenting at a weekend, but neither reached statistical significance. There was a significantly greater risk of combined unadjusted in hospital, 30 and 90 day mortality for those presenting at a weekend (OR 1.17, 95% CI 1.09 – 1.27, p < .001). Hospital length of stay was not statistically different between groups.

      Conclusion

      There is an association between weekend admission and higher mortality in patients presenting with ruptured abdominal aortic aneurysm.

      Keywords

      There has been much debate around the presence of a weekend effect on the management of ruptured abdominal aortic aneurysms. Meta-analysis of 12 studies comprising a total of 95 856 patients demonstrated a significantly higher risk of combined unadjusted in hospital, 30 day, and 90 day all cause mortality for those treated over the weekend vs. their weekday counterparts. This study calls into question the current out of hours vascular provision and whether a more equitable seven day service is required.

      Introduction

      Rupture of an abdominal aortic aneurysm (rAAA) is an emergency condition with a high mortality.
      • Lindholt J.S.
      • Søgaard R.
      • Laustsen J.
      Prognosis of ruptured abdominal aortic aneurysms in Denmark from 1994-2008.
      Due to its unpredictable nature, patients require surgical intervention around the clock, including at weekends. A number of studies have shown patients admitted over the weekend have poorer outcomes than their weekday counterparts for a number of conditions,
      • Pauls L.A.
      • Johnson-Paben R.
      • McGready J.
      • Murphy J.D.
      • Pronovost P.J.
      • Wu C.L.
      The weekend effect in hospitalized patients: a meta-analysis.
      • Takagi H.
      • Ando T.
      • Umemoto T.
      ALICE (All-Literature Investigation of Cardiovascular Evidence) group. A meta-analysis of weekend admission and surgery for aortic rupture and dissection.
      • Magid D.J.
      • Wang Y.
      • Herrin J.
      • McNamara R.L.
      • Bradley E.H.
      • Curtis J.P.
      • et al.
      Relationship between time of day, day of week, timeliness of reperfusion, and in-hospital mortality for patients with acute ST-segment elevation myocardial infarction.
      • Ricciardi R.
      • Roberts P.L.
      • Read T.E.
      • Baxter N.N.
      • Marcello P.W.
      • Schoetz D.J.
      Mortality rate after nonelective hospital admission.
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      with delayed diagnosis, delay in activation of treating team,
      • Magid D.J.
      • Wang Y.
      • Herrin J.
      • McNamara R.L.
      • Bradley E.H.
      • Curtis J.P.
      • et al.
      Relationship between time of day, day of week, timeliness of reperfusion, and in-hospital mortality for patients with acute ST-segment elevation myocardial infarction.
      poorer staffing levels,
      • Ricciardi R.
      • Roberts P.L.
      • Read T.E.
      • Baxter N.N.
      • Marcello P.W.
      • Schoetz D.J.
      Mortality rate after nonelective hospital admission.
      and lower levels of expertise
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      all being cited as possible contributing factors. A recent meta-analysis looking into ruptured abdominal and thoracic aortic aneurysms as well as acute aortic dissection including 116 195 patients suggested there is an out of hours effect for this patient group;
      • Takagi H.
      • Ando T.
      • Umemoto T.
      ALICE (All-Literature Investigation of Cardiovascular Evidence) group. A meta-analysis of weekend admission and surgery for aortic rupture and dissection.
      however, other studies limited just to rAAA suggest the effect may not be significant.
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      Therefore, a meta-analysis was undertaken to determine whether weekend admission for rAAA is associated with poorer outcomes.

      Materials and methods

      Review design

      The objectives and methodology of the review were pre-specified in a protocol which was registered at the international Prospective Register of Systematic Reviews in Health and Social Care (PROSPERO) (CRD42020157484).

      University of York, Centre for Reviews and Dissemination, York, UK. PROSPERO: international prospective register of systematic reviews. Available at: http://www.crd.york.ac.uk/PROSPERO/ [Accessed 19 January 2020].

      The review was conducted and is reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines.
      • Liberati A.
      • Altman D.G.
      • Tetzlaff J.
      • Mulrow C.
      • Gøtzsche P.C.
      • Ioannidis J.P.A.
      • et al.
      The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate healthcare interventions: explanation and elaboration.

      Criteria for considering studies and study selection

      Two review authors (R.L., M.S.) conducted the pre-specified literature searches and evaluated the eligibility of studies independently. Where disagreement arose a third review author (G.A.) acted as arbitrator.

      Types of studies

      All types of studies investigating the role of admission at the weekend as a prognostic factor in the management of rAAA were considered.

      Types of participants

      Eligible participants were men or women of any age with a confirmed diagnosis of rAAA either on imaging or at time of laparotomy who underwent emergency open or endovascular repair for their condition or were selected for conservative management. Patients with thoracic aortic aneurysms (TAAs) and those with symptomatic but not rAAAs were excluded. Those patients who underwent complex endovascular repair including chimney, fenestrated and branched grafts were also excluded from the study.

      Types of prognostic factor

      The prognostic factor of interest was admission for rAAA at the weekend. Eligible studies should have compared outcomes in patients who were admitted for rAAA at the weekend with those who were admitted on a weekday. For the purposes of this review, national holidays were counted as weekend days.

      Types of outcome measure

      The impact of weekend admission on the outcomes of patients presenting with rAAA was investigated. The following outcome measures were used.
      Primary outcome measures: In hospital all cause mortality; 30 day all cause mortality; 90 day all cause mortality.
      Secondary outcome measure: Length of hospital stay.

      Search methods for identification of studies

      The literature search strategy was developed by the review author team with experience in outreach, knowledge and evidence search.

      Electronic measures

      The Healthcare Databases Advanced Search (HDAS) interface developed by the National Institute for Health and Care Excellence (NICE) was used to interrogate electronic bibliographic sources. The following electronic bibliographic databases were interrogated: Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica Database (EMBASE), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL). Relevant terms were selected to identify eligible reports. Thesaurus headings, search operators and limits in each of the above databases were adapted accordingly. No language constraints were applied. The literature search was run in October 2019. The search strategy is presented in Appendix 1.

      Searching other sources

      The bibliographic lists of relevant studies were screened for additional studies.

      Data extraction and management

      One review author extracted data from the selected studies (R.L.), with the data cross checked by a second review author (M.S.). The following information was collected:
      • Study related data (first author, year and journal of publication, country where the study was conducted, single or multicentre study, use of national/regional/local database, retrospective or prospective study design, recruitment period for study, inclusion/exclusion criteria, definition of “weekend”).
      • Baseline demographics and clinical characteristics of the study populations (age, sex, hypertension, diabetes mellitus, chronic obstructive pulmonary disease, chronic kidney disease, treatment provided: open/endovascular aneurysm repair/conservative).
      • Data pertaining to the study quality assessment (as outlined in the “Study quality assessment” section).
      • Outcome data (as outlined in the “Criteria for considering studies and study selection” section), along with factors for which mortality adjustment was made if applicable.

      Study quality assessment

      The methodological quality of the studies was assessed with a modified Newcastle–Ottawa scale (NOS).

      Wells GA, Shea B, O’Connell D, Peterson J, Welch V, Losos M, et al. The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomized studies in meta-analyses. Available at: http://www.ohri.ca/programs/clinical_ epidemiology/oxford.htm [Accessed 19 January 2020].

      Using the tool, each study was judged on eight items, categorised into three groups: the selection of the study groups, the comparability of the groups, and the assessment of the outcome. Stars awarded for each quality item served as a quick visual assessment. Stars were awarded such that the highest quality studies were awarded up to nine stars. Two review authors (R.L., M.S.) assessed the quality of the selected studies. Where disagreement arose a third review author (G.A.) arbitrated.

      Methods of quantitative synthesis

      Measures of treatment effect

      Pooled estimates of dichotomous outcome data were calculated using the odds ratio (OR) and 95% confidence interval (CI). Meta-analyses were also conducted of risk adjusted comparative observational studies for peri-operative/90 day mortality using the inverse variance method and the results were reported as summary OR and associated 95% CI.

      Unit of analysis

      The unit of analysis was the individual patient.

      Assessment of heterogeneity

      In between study heterogeneity was examined with the Cochrane’s Q (χ2) test. Inconsistency was quantified by calculating I2 and interpreted with the following guide: 0% – 40% might not be important; 30% – 60% may represent moderate heterogeneity; 50% – 90% may represent substantial heterogeneity; and 75% – 100% may represent considerable heterogeneity.
      • Deek J.J.
      • Higgins J.P.T.
      • Altman D.G.
      Analysing data and undertaking meta-analyses. Chapter 10.

      Assessment of reporting bias

      Publication bias was assessed both visually evaluating the symmetry of the funnel plot and mathematically using the Egger’s regression intercept when 10 or more studies were available.

      Missing data

      No attempt was made to contact authors of included studies to enquire about missing or incomplete data.

      Statistical models

      In view of the anticipated variability in treatment methods and the clinical and methodological diversity among the selected studies, the summary outcome estimates were calculated using the random effects models of DerSimonian and Laird.
      • DerSimonian R.
      • Laird N.
      Meta-analysis in clinical trials.
      A forest plot was created for each treatment effect.

      Sensitivity and subgroup analysis

      Sensitivity analysis was performed excluding studies that were judged to be of high risk of bias (achieving < 7 stars in the NOS) in order to assess whether the included studies, deemed to be biased, impacted the final analysis. Furthermore, one study was excluded at a time and the meta-analysis was repeated in order to assess the impact of the individual studies on the pooled estimates. A subgroup analysis for open and endovascular management was performed.

      Statistical software

      For data synthesis, the following statistical software applications were used:
      • Review Manager (RevMan) (Computer program). Version 5.3. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014.
      • Comprehensive Meta-Analysis (CMA) software (Biostat, Englewood, NJ, USA).

      Results

      Results of the literature search

      The literature search identified 76 records. Forty were deemed irrelevant to the topic and excluded. Of those papers deemed relevant, 14 were duplicate records. The full texts of the remaining 22 studies were assessed with 12 eligible studies meeting the inclusion criteria,
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      ,
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      ,
      • O’Donnell T.F.X.
      • Li C.
      • Swerdlow N.J.
      • Liang P.
      • Pothof A.B.
      • Patel V.I.
      • et al.
      The weekend effect in AAA repair.
      • Glance L.G.
      • Osler T.
      • Li Y.
      • Lustik S.J.
      • Eaton M.P.
      • Dutton R.P.
      • et al.
      Outcomes are worse in US patients undergoing surgery on weekends compared with weekdays.
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      • Mell M.W.
      • Wang N.E.
      • Morrison D.E.
      • Hernandez-Boussard T.
      Interfacility transfer and mortality for patients with ruptured abdominal aortic aneurysm.
      • Kózka M.A.
      • Bijak P.
      • Chwala M.
      • Mrowiecki T.
      • Kotynia M.
      • Kaczmarek B.
      • et al.
      The impact of weather factors, moon phases, and seasons on abdominal aortic aneurysm rupture.
      • Groves E.M.
      • Khoshchehreh M.
      • Le C.
      • Malik S.
      Effects of weekend admission on the outcomes and management of ruptured aortic aneurysms.
      • Gallerani M.
      • Imberti D.
      • Bossone E.
      • Eagle K.A.
      • Manfredini R.
      Higher mortality in patients hospitalized for acute aortic rupture or dissection during weekends.
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      • Ozdemir B.A.
      • Karthikesalingam A.
      • Sinha S.
      • Poloniecki J.D.
      • Vidal-Diez A.
      • Hinchliffe R.J.
      • et al.
      Association of hospital structures with mortality from ruptured abdominal aortic aneurysm.
      • Gallerani M.
      • Volpato S.
      • Boari B.
      • Pala M.
      • De Giorgi A.
      • Fabbian F.
      • et al.
      Outcomes of weekend versus weekday admission for acute aortic dissection or rupture: a retrospective study on the Italian National Hospital Database.
      investigating the prognostic role of weekend admission in patients diagnosed with rAAA. All papers excluded after full text review were removed because they did not provide data for the primary outcome measures. Two studies assessed two separate cohorts in different geographical regions giving separate outcome analyses for each. These two groups were therefore analysed separately giving 14 patient cohorts for analysis. The two studies of Karthikesalingam et al. reported different outcome endpoints. Since there was no overlap in meta-analysed data, it was decided to include both cohorts in the meta-analysis in order to provide a more robust analysis A flow diagram of the results of the literature search is presented in Appendix 2.

      Description of studies

      Of the 14 patient cohorts, all but one cohort were multicentre, with 10 of these using national administrative databases and three regional databases. All studies were of a retrospective design published between 2001 and 2019 with recruitment periods extending from 1988 to 2017. Five patient cohorts were from the USA, four from the UK, two from Italy, and one from each Sweden, Canada, and Poland. Seven studies included all patients admitted with a diagnosis of rAAA in their analysis while the other seven only looked at those receiving operative management. The study characteristics and criteria for patient inclusion are presented in Table 1, Table 2 respectively. Patient characteristics and demographics for each included study are presented in Table 3. Seven studies performed risk adjustment mortality analysis. Factors for which adjustments were made, along with primary outcome data for each included study are presented in Table 4. Secondary outcome and sub-analysis data are presented in Table 5.
      Table 1Information on 14 included studies investigating the prognostic role of weekend admission in patients diagnosed with ruptured abdominal aortic aneurysm
      First author (year)JournalCountry
      Country of corresponding author.
      Recruitment periodRetrospective/prospectiveSingle/multicentreAdministrative database typePatients – n
      TotalTreated at the weekendTreated on weekday
      O’Donnell (2019)
      • O’Donnell T.F.X.
      • Li C.
      • Swerdlow N.J.
      • Liang P.
      • Pothof A.B.
      • Patel V.I.
      • et al.
      The weekend effect in AAA repair.
      Ann SurgUSA2009–2017RetrospectiveMulticentreNational3 1128862 226
      Ambler (2017)
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      BJSUK2013–2015RetrospectiveMulticentreNational3 1211 0522 069
      Glance (2016)
      • Glance L.G.
      • Osler T.
      • Li Y.
      • Lustik S.J.
      • Eaton M.P.
      • Dutton R.P.
      • et al.
      Outcomes are worse in US patients undergoing surgery on weekends compared with weekdays.
      Med CareUSA2009–2011RetrospectiveMulticentreNational3 4093873 022
      Karthikesalingam – English cohort (2016)
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      BJSUK2003–2012RetrospectiveMulticentreNational12 4673 1029 365
      Karthikesalingam – Swedish cohort (2016)
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      BJSUK2003–2012RetrospectiveMulticentreNational2 8297062 123
      Ozdemir (2015)
      • Ozdemir B.A.
      • Karthikesalingam A.
      • Sinha S.
      • Poloniecki J.D.
      • Vidal-Diez A.
      • Hinchliffe R.J.
      • et al.
      Association of hospital structures with mortality from ruptured abdominal aortic aneurysm.
      BJSUK2005–2010RetrospectiveMulticentreNational9 877NRNR
      Groves (2014)
      • Groves E.M.
      • Khoshchehreh M.
      • Le C.
      • Malik S.
      Effects of weekend admission on the outcomes and management of ruptured aortic aneurysms.
      JVSUSA2009RetrospectiveMulticentreNational5 8001 4324 368
      Karthikesalingam – English cohort (2014)
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      LancetUK2005–2010RetrospectiveMulticentreNational11 799NRNR
      Karthikesalingam – American cohort (2014)
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      LancetUK2005–2010RetrospectiveMulticentreNational2 3838NRNR
      Kózka (2014)
      • Kózka M.A.
      • Bijak P.
      • Chwala M.
      • Mrowiecki T.
      • Kotynia M.
      • Kaczmarek B.
      • et al.
      The impact of weather factors, moon phases, and seasons on abdominal aortic aneurysm rupture.
      Ann Vasc SurgPoland2002–2011RetrospectiveSingle centreLocal530134396
      Mell (2014)
      • Mell M.W.
      • Wang N.E.
      • Morrison D.E.
      • Hernandez-Boussard T.
      Interfacility transfer and mortality for patients with ruptured abdominal aortic aneurysm.
      JVSUSA2005–2010RetrospectiveMulticentreState4 439NRNR
      Gallerani (2013)
      • Gallerani M.
      • Volpato S.
      • Boari B.
      • Pala M.
      • De Giorgi A.
      • Fabbian F.
      • et al.
      Outcomes of weekend versus weekday admission for acute aortic dissection or rupture: a retrospective study on the Italian National Hospital Database.
      IJCItaly2008–2010RetrospectiveMulticentreNational7 3395 5061 833
      Gallerani (2012)
      • Gallerani M.
      • Imberti D.
      • Bossone E.
      • Eagle K.A.
      • Manfredini R.
      Higher mortality in patients hospitalized for acute aortic rupture or dissection during weekends.
      JVSItaly1999–2009RetrospectiveMulticentreRegional1 8425341 308
      Bell (2001)
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      NEJMCanada1988–1997RetrospectiveMulticentreRegional5 4541 3094 145
      BJS = Br J Surg; IJC = Int J Cardiol; JVS = J Vasc Surg; NEJM = N Engl J Med; NR = not recorded.
      Country of corresponding author.
      Table 2Information on patient inclusion and exclusion in included studies investigating the prognostic role of weekend admission in patients diagnosed with ruptured abdominal aortic aneurysm
      First authorInclusion criteria for patient enrolmentExclusion criteria for patient enrolmentWeekend definition
      O’Donnell
      • O’Donnell T.F.X.
      • Li C.
      • Swerdlow N.J.
      • Liang P.
      • Pothof A.B.
      • Patel V.I.
      • et al.
      The weekend effect in AAA repair.
      All patients undergoing rAAA repairPrevious AAA repairSaturday and Sunday
      Ambler
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      All patients undergoing rAAA repairMissing dataFriday 17:00 to Monday 08:00
      Glance
      • Glance L.G.
      • Osler T.
      • Li Y.
      • Lustik S.J.
      • Eaton M.P.
      • Dutton R.P.
      • et al.
      Outcomes are worse in US patients undergoing surgery on weekends compared with weekdays.
      All patients undergoing emergency AAA repairMissing data

      Transfer to another centre
      Saturday and Sunday – operated same day
      Karthikesalingam – English cohort
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      All patients undergoing rAAA repairAge <50“Weekend” – but not defined
      Karthikesalingam – Swedish cohort
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      All patients undergoing rAAA repairAge <50“Weekend” – but not defined
      Ozdemir
      • Ozdemir B.A.
      • Karthikesalingam A.
      • Sinha S.
      • Poloniecki J.D.
      • Vidal-Diez A.
      • Hinchliffe R.J.
      • et al.
      Association of hospital structures with mortality from ruptured abdominal aortic aneurysm.
      All patients admitted with rAAANRAdmission on a Saturday or Sunday
      Groves
      • Groves E.M.
      • Khoshchehreh M.
      • Le C.
      • Malik S.
      Effects of weekend admission on the outcomes and management of ruptured aortic aneurysms.
      All patients admitted with rAAANRAdmission between Friday midnight and Sunday midnight
      Karthikesalingam – English cohort
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      All patients admitted with rAAANRAdmission at a “weekend” (but not defined)
      Karthikesalingam – American cohort
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      All patients admitted with rAAANRAdmission at a “weekend” (but not defined)
      Kózka
      • Kózka M.A.
      • Bijak P.
      • Chwala M.
      • Mrowiecki T.
      • Kotynia M.
      • Kaczmarek B.
      • et al.
      The impact of weather factors, moon phases, and seasons on abdominal aortic aneurysm rupture.
      All patients undergoing rAAA repairPatient death before surgeryAdmission at “weekend” or national holidays (but not defined)
      Mell
      • Mell M.W.
      • Wang N.E.
      • Morrison D.E.
      • Hernandez-Boussard T.
      Interfacility transfer and mortality for patients with ruptured abdominal aortic aneurysm.
      All patients undergoing rAAA repairAge <18

      Missing data

      Previous AAA repair

      Transfer to another centre
      Admission at a “weekend” (but not defined)
      Gallerani
      • Gallerani M.
      • Volpato S.
      • Boari B.
      • Pala M.
      • De Giorgi A.
      • Fabbian F.
      • et al.
      Outcomes of weekend versus weekday admission for acute aortic dissection or rupture: a retrospective study on the Italian National Hospital Database.
      All patients admitted with rAAATraumatic AARDAdmission between Friday midnight and Sunday midnight
      Gallerani
      • Gallerani M.
      • Imberti D.
      • Bossone E.
      • Eagle K.A.
      • Manfredini R.
      Higher mortality in patients hospitalized for acute aortic rupture or dissection during weekends.
      All patients admitted with rAAATraumatic AARDAdmission between Friday midnight and Sunday midnight
      Bell
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      All patients admitted with rAAANRAdmission between Friday midnight and Sunday midnight
      AAA = abdominal aortic aneurysm; AARD = acute aortic rupture or dissection; NR = not recorded; rAAA = ruptured abdominal aortic aneurysm.
      Table 3Demographic and clinical data for included studies investigating the prognostic role of weekend admission in patients diagnosed with ruptured abdominal aortic aneurysm
      First author (year)Patients – nDemographics presented as weekday/weekend – %
      Mean age – yMale genderHypertensionDiabetes mellitusCOPDCKDEVAROpen aneurysm repairPalliative
      O’Donnell (2019)
      • O’Donnell T.F.X.
      • Li C.
      • Swerdlow N.J.
      • Liang P.
      • Pothof A.B.
      • Patel V.I.
      • et al.
      The weekend effect in AAA repair.
      3 11273 ± 10/73 ± 977/7879/8016/1630/3143/4656/5644/44N/A
      Ambler (2017)
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      3 121NRNRNRNRNRNR2773N/A
      Glance (2016)
      • Glance L.G.
      • Osler T.
      • Li Y.
      • Lustik S.J.
      • Eaton M.P.
      • Dutton R.P.
      • et al.
      Outcomes are worse in US patients undergoing surgery on weekends compared with weekdays.
      3 409NRNRNRNRNRNR64/4936/51N/A
      Karthikesalingam – English cohort (2016)
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      12 46776.7 ± 7.6/74.2 ± 7.683/84NR7/713/126/510/890/92N/A
      Karthikesalingam – Swedish cohort (2016)
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      2 82974.1 ± 8.0/74.5 ±7.682/80NR10/921/2215/1617/1583/85N/A
      Ozdemir (2015)
      • Ozdemir B.A.
      • Karthikesalingam A.
      • Sinha S.
      • Poloniecki J.D.
      • Vidal-Diez A.
      • Hinchliffe R.J.
      • et al.
      Association of hospital structures with mortality from ruptured abdominal aortic aneurysm.
      9 8777874NRNRNRNRNRNR42
      Groves (2014)
      • Groves E.M.
      • Khoshchehreh M.
      • Le C.
      • Malik S.
      Effects of weekend admission on the outcomes and management of ruptured aortic aneurysms.
      5 80075.4 ± 10.5/74.4 ± 10.050/5873/6413/1726/2718/2124/2545/4630/29
      Karthikesalingam – English cohort (2014)
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      11 799NRNRNRNRNRNR55342
      Karthikesalingam – American cohort (2014)
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      23 838NRNRNRNRNRNR176420
      Kozka (2014)
      • Kózka M.A.
      • Bijak P.
      • Chwala M.
      • Mrowiecki T.
      • Kotynia M.
      • Kaczmarek B.
      • et al.
      The impact of weather factors, moon phases, and seasons on abdominal aortic aneurysm rupture.
      53072.2 ± 8.483NRNRNRNR0100N/A
      Mell (2014)
      • Mell M.W.
      • Wang N.E.
      • Morrison D.E.
      • Hernandez-Boussard T.
      Interfacility transfer and mortality for patients with ruptured abdominal aortic aneurysm.
      4 439NRNRNRNRNRNRNRNRNR
      Gallerani (2013)
      • Gallerani M.
      • Volpato S.
      • Boari B.
      • Pala M.
      • De Giorgi A.
      • Fabbian F.
      • et al.
      Outcomes of weekend versus weekday admission for acute aortic dissection or rupture: a retrospective study on the Italian National Hospital Database.
      7 339NRNRNRNRNRNRNRNRNR
      Gallerani (2012)
      • Gallerani M.
      • Imberti D.
      • Bossone E.
      • Eagle K.A.
      • Manfredini R.
      Higher mortality in patients hospitalized for acute aortic rupture or dissection during weekends.
      1 842NRNRNRNRNRNRNRNRNR
      Bell (2001)
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      5 454NRNRNRNRNRNRNRNRN/A
      Data are presented as % or mean ± standard deviation for weekday/weekend where available. CKD = chronic kidney disease; COPD = chronic obstructive pulmonary disease; EVAR = endovascular aneurysm repair; N/A = not applicable; NR = not recorded.
      Table 4Information on primary outcome data for included studies investigating the prognostic role of weekend admission in patients diagnosed with ruptured abdominal aortic aneurysm
      First author (year)Patients – nFactors OR adjusted for (if applicable)30 d mortality – %
      Data presented for weekday/weekend.
      In hospital mortality – %
      Data presented for weekday/weekend.
      In hospital mortality OR (95% CI)
      AOR and OR presented as weekend vs. weekday.
      In hospital mortality AOR (95% CI)
      AOR and OR presented as weekend vs. weekday.
      90 d mortality – %
      Data presented for weekday/weekend.
      90 d mortality AOR (95% CI)
      AOR and OR presented as weekend vs. weekday.
      O’Donnell (2019)
      • O’Donnell T.F.X.
      • Li C.
      • Swerdlow N.J.
      • Liang P.
      • Pothof A.B.
      • Patel V.I.
      • et al.
      The weekend effect in AAA repair.
      3 112N/A25/28NRNRNRNRNR
      Ambler (2017)
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      3 121Demographics

      Co-morbidities

      Medications

      Pre-operative test results
      NR36/401.17 (1.00–1.36)1.09 (0.92–1.29)NRNR
      Glance (2016)
      • Glance L.G.
      • Osler T.
      • Li Y.
      • Lustik S.J.
      • Eaton M.P.
      • Dutton R.P.
      • et al.
      Outcomes are worse in US patients undergoing surgery on weekends compared with weekdays.
      3 409Demographics (age, sex, and race)

      Payer status

      Procedure type

      Transfer status

      Co-morbidities
      NRNRNR1.24 (0.86–1.80) for open;

      3.20 (1.98–5.17) for EVAR
      NRNR
      Karthikesalingam – English cohort (2016)
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      12 467N/ANRNRNRNR44/44NR
      Karthikesalingam – Swedish cohort (2016)
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      2 829N/ANRNRNRNR32/38NR
      Ozdemir (2015)
      • Ozdemir B.A.
      • Karthikesalingam A.
      • Sinha S.
      • Poloniecki J.D.
      • Vidal-Diez A.
      • Hinchliffe R.J.
      • et al.
      Association of hospital structures with mortality from ruptured abdominal aortic aneurysm.
      9 877Age

      Sex

      Co-morbidities

      Deprivation indices
      NRNRNRNRNR1.16 (1.04–1.30)
      Groves (2014)
      • Groves E.M.
      • Khoshchehreh M.
      • Le C.
      • Malik S.
      Effects of weekend admission on the outcomes and management of ruptured aortic aneurysms.
      5 800Demographics

      Insurance

      Hospital characteristics

      Co-morbidities
      NR44/46NR1.32 (1.13–1.55)NRNR
      Karthikesalingam – English cohort (2014)
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      11 799Age

      Sex

      Co-morbidities

      Year

      Hospital size or caseload
      NRNRNR1.144 (1.037–1.263)NRNR
      Karthikesalingam – American cohort (2014)
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      23 838Age

      Sex

      Co-morbidities

      Year

      Hospital size or caseload
      NRNRNR1.156 (1.005–1.337)NRNR
      Kozka (2014)
      • Kózka M.A.
      • Bijak P.
      • Chwala M.
      • Mrowiecki T.
      • Kotynia M.
      • Kaczmarek B.
      • et al.
      The impact of weather factors, moon phases, and seasons on abdominal aortic aneurysm rupture.
      530N/ANR45/59NRNRNRNR
      Mell (2014)
      • Mell M.W.
      • Wang N.E.
      • Morrison D.E.
      • Hernandez-Boussard T.
      Interfacility transfer and mortality for patients with ruptured abdominal aortic aneurysm.
      4 439Operative cases onlyNRNR1.11 (0.96–1.28)1.09 (0.95–1.27)NRNR
      Gallerani (2013)
      • Gallerani M.
      • Volpato S.
      • Boari B.
      • Pala M.
      • De Giorgi A.
      • Fabbian F.
      • et al.
      Outcomes of weekend versus weekday admission for acute aortic dissection or rupture: a retrospective study on the Italian National Hospital Database.
      7 339N/ANRNR1.67 (1.02–1.33)NRNRNR
      Gallerani (2012)
      • Gallerani M.
      • Imberti D.
      • Bossone E.
      • Eagle K.A.
      • Manfredini R.
      Higher mortality in patients hospitalized for acute aortic rupture or dissection during weekends.
      1 842N/ANR47/511.149 (0.939–1.405)NRNRNR
      Bell (2001)
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      5 454Age

      Sex

      Charlson Comorbidity Index
      NR36/42NR1.28 (1.13–1.46)NRNR
      AOR = adjusted odds ratio; CI = confidence interval; N/A = not applicable; NR = not recorded; OR = odds ratio.
      Data presented for weekday/weekend.
      AOR and OR presented as weekend vs. weekday.
      Table 5Table of secondary outcome and sub-analysis data for included studies investigating the prognostic role of weekend admission in patients diagnosed with ruptured abdominal aortic aneurysm
      First author (year)Patients – nMean hospital length of stay – d
      Data presented for weekday/weekend.
      Prolonged hospital length of stay OR (95% CI)
      AOR and OR presented as weekend vs. weekday.
      ,
      Greater than median LOS in dataset.
      EVAR mortality – %
      Data presented for weekday/weekend.
      Open mortality – %
      Data presented for weekday/weekend.
      EVAR OR (95% CI)
      AOR and OR presented as weekend vs. weekday.
      Open OR (95% CI)
      AOR and OR presented as weekend vs. weekday.
      O’Donnell (2019)
      • O’Donnell T.F.X.
      • Li C.
      • Swerdlow N.J.
      • Liang P.
      • Pothof A.B.
      • Patel V.I.
      • et al.
      The weekend effect in AAA repair.
      3 112NRNRNRNRNRNR
      Ambler (2017)
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      3 121NR1.06 (0.91–1.10)NRNRNRNR
      Glance (2016)
      • Glance L.G.
      • Osler T.
      • Li Y.
      • Lustik S.J.
      • Eaton M.P.
      • Dutton R.P.
      • et al.
      Outcomes are worse in US patients undergoing surgery on weekends compared with weekdays.
      3 409NRNRNRNR3.20 (1.98–5.17)1.24 (0.86–1.80)
      Karthikesalingam – English cohort (2016)
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      12 467NRNR33/3345/45NRNR
      Karthikesalingam – Swedish cohort (2016)
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      2 829NRNR25/2633/40NRNR
      Ozdemir (2015)
      • Ozdemir B.A.
      • Karthikesalingam A.
      • Sinha S.
      • Poloniecki J.D.
      • Vidal-Diez A.
      • Hinchliffe R.J.
      • et al.
      Association of hospital structures with mortality from ruptured abdominal aortic aneurysm.
      9 877NRNRNRNRNRNR
      Groves
      • Groves E.M.
      • Khoshchehreh M.
      • Le C.
      • Malik S.
      Effects of weekend admission on the outcomes and management of ruptured aortic aneurysms.
      5 8009.4 ± 13.7/8.8 ± 10.4NRNRNRNRNR
      Karthikesalingam – English cohort (2014)
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      11 799NRNRNRNRNRNR
      Karthikesalingam – American cohort (2014)
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      23 838NRNRNRNRNRNR
      Kozka (2014)
      • Kózka M.A.
      • Bijak P.
      • Chwala M.
      • Mrowiecki T.
      • Kotynia M.
      • Kaczmarek B.
      • et al.
      The impact of weather factors, moon phases, and seasons on abdominal aortic aneurysm rupture.
      530NRNRNRNRNRNR
      Mell (2014)
      • Mell M.W.
      • Wang N.E.
      • Morrison D.E.
      • Hernandez-Boussard T.
      Interfacility transfer and mortality for patients with ruptured abdominal aortic aneurysm.
      4 439NRNRNRNRNRNR
      Gallerani (2013)
      • Gallerani M.
      • Volpato S.
      • Boari B.
      • Pala M.
      • De Giorgi A.
      • Fabbian F.
      • et al.
      Outcomes of weekend versus weekday admission for acute aortic dissection or rupture: a retrospective study on the Italian National Hospital Database.
      7 339NRNRNRNRNRNR
      Gallerani (2012)
      • Gallerani M.
      • Imberti D.
      • Bossone E.
      • Eagle K.A.
      • Manfredini R.
      Higher mortality in patients hospitalized for acute aortic rupture or dissection during weekends.
      1 842NRNRNRNRNRNR
      Bell (2001)
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      5 454NRNRNRNRNRNR
      Data presented as OR (95% CI) or mean ± standard deviation. OR presented as weekend vs. weekday. CI = confidence interval; EVAR = endovascular aneurysm repair; LOS = length of stay; NR = not recorded; OR = odds ratio.
      Data presented for weekday/weekend.
      AOR and OR presented as weekend vs. weekday.
      Greater than median LOS in dataset.

      Results of study quality assessment

      The quality of included studies was assessed by the NOS.

      Wells GA, Shea B, O’Connell D, Peterson J, Welch V, Losos M, et al. The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomized studies in meta-analyses. Available at: http://www.ohri.ca/programs/clinical_ epidemiology/oxford.htm [Accessed 19 January 2020].

      Five studies scored eight points, eight scored seven points, and one scored six points of a possible nine. The results of the methodological quality assessment indicated in the NOS scores are presented in Table 6.
      Table 6Quality related data according to the Newcastle-Ottawa Scale for included studies investigating the prognostic role of weekend admission in patients diagnosed with ruptured abdominal aortic aneurysm
      First author (year)SelectionComparabilityOutcomeTotal
      O’Donnell (2019)
      • O’Donnell T.F.X.
      • Li C.
      • Swerdlow N.J.
      • Liang P.
      • Pothof A.B.
      • Patel V.I.
      • et al.
      The weekend effect in AAA repair.
      4228
      Ambler (2017)
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      3227
      Glance (2016)
      • Glance L.G.
      • Osler T.
      • Li Y.
      • Lustik S.J.
      • Eaton M.P.
      • Dutton R.P.
      • et al.
      Outcomes are worse in US patients undergoing surgery on weekends compared with weekdays.
      3227
      Karthikesalingam – English cohort (2016)
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      4228
      Karthikesalingam – Swedish cohort (2016)
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      4228
      Ozdemir (2015)
      • Ozdemir B.A.
      • Karthikesalingam A.
      • Sinha S.
      • Poloniecki J.D.
      • Vidal-Diez A.
      • Hinchliffe R.J.
      • et al.
      Association of hospital structures with mortality from ruptured abdominal aortic aneurysm.
      4228
      Groves (2014)
      • Groves E.M.
      • Khoshchehreh M.
      • Le C.
      • Malik S.
      Effects of weekend admission on the outcomes and management of ruptured aortic aneurysms.
      3227
      Karthikesalingam – English cohort (2014)
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      3227
      Karthikesalingam – American cohort (2014)
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      3227
      Kozka (2014)
      • Kózka M.A.
      • Bijak P.
      • Chwala M.
      • Mrowiecki T.
      • Kotynia M.
      • Kaczmarek B.
      • et al.
      The impact of weather factors, moon phases, and seasons on abdominal aortic aneurysm rupture.
      4026
      Mell (2014)
      • Mell M.W.
      • Wang N.E.
      • Morrison D.E.
      • Hernandez-Boussard T.
      Interfacility transfer and mortality for patients with ruptured abdominal aortic aneurysm.
      4228
      Gallerani (2013)
      • Gallerani M.
      • Volpato S.
      • Boari B.
      • Pala M.
      • De Giorgi A.
      • Fabbian F.
      • et al.
      Outcomes of weekend versus weekday admission for acute aortic dissection or rupture: a retrospective study on the Italian National Hospital Database.
      3227
      Gallerani (2012)
      • Gallerani M.
      • Imberti D.
      • Bossone E.
      • Eagle K.A.
      • Manfredini R.
      Higher mortality in patients hospitalized for acute aortic rupture or dissection during weekends.
      3227
      Bell (2001)
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      3227

      Results of reporting bias

      Publication bias was investigated for the outcome “unadjusted 30 day or in hospital or 90 day mortality” only, as this was the only outcome that is reported by 10 or more studies. There was statistical evidence of publication or reporting bias (p = .007). A funnel plot of the data is presented in Appendix 3.

      Results of data synthesis

      Primary outcome measures

      Fourteen cohorts comprising of 95 856 patients reported all cause mortality data for meta-analysis for the primary outcomes:

      Unadjusted 30 day mortality

      One cohort reporting a total of 3 112 patients (886 treated over the weekend and 2 226 treated on a weekday) reported unadjusted 30 day mortality data.
      • O’Donnell T.F.X.
      • Li C.
      • Swerdlow N.J.
      • Liang P.
      • Pothof A.B.
      • Patel V.I.
      • et al.
      The weekend effect in AAA repair.
      The study found a higher risk of 30 day mortality in patients treated over the weekend, but this was not statistically significant (OR 1.16, 95% CI 0.98 – 1.39, p = .090) (Fig. 1A).
      Figure 1
      Figure 1Forest plots of outcomes in patients treated over a weekend vs. those treated on a weekday: (A) 30 day mortality; (B) in hospital mortality; (C) adjusted in hospital mortality; (D) 90 day mortality; (E) adjusted 90 day mortality; (F) 30 day or in hospital or 90 day mortality; (G) hospital length of stay. The solid squares denote the odds ratios or mean differences, the horizontal lines represent the 95% confidence intervals (CI), and the diamonds denote the pooled odds ratio or mean difference. IV = inverse variance; M-H = Mantel–Haenszel; SD = standard deviation; SE = standard error.
      Figure 1
      Figure 1Forest plots of outcomes in patients treated over a weekend vs. those treated on a weekday: (A) 30 day mortality; (B) in hospital mortality; (C) adjusted in hospital mortality; (D) 90 day mortality; (E) adjusted 90 day mortality; (F) 30 day or in hospital or 90 day mortality; (G) hospital length of stay. The solid squares denote the odds ratios or mean differences, the horizontal lines represent the 95% confidence intervals (CI), and the diamonds denote the pooled odds ratio or mean difference. IV = inverse variance; M-H = Mantel–Haenszel; SD = standard deviation; SE = standard error.

      Unadjusted in hospital mortality

      Seven cohorts comprising of a total of 28 525 patients reported unadjusted in hospital mortality data.
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      ,
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      ,
      • Mell M.W.
      • Wang N.E.
      • Morrison D.E.
      • Hernandez-Boussard T.
      Interfacility transfer and mortality for patients with ruptured abdominal aortic aneurysm.
      • Kózka M.A.
      • Bijak P.
      • Chwala M.
      • Mrowiecki T.
      • Kotynia M.
      • Kaczmarek B.
      • et al.
      The impact of weather factors, moon phases, and seasons on abdominal aortic aneurysm rupture.
      • Groves E.M.
      • Khoshchehreh M.
      • Le C.
      • Malik S.
      Effects of weekend admission on the outcomes and management of ruptured aortic aneurysms.
      • Gallerani M.
      • Imberti D.
      • Bossone E.
      • Eagle K.A.
      • Manfredini R.
      Higher mortality in patients hospitalized for acute aortic rupture or dissection during weekends.
      ,
      • Gallerani M.
      • Volpato S.
      • Boari B.
      • Pala M.
      • De Giorgi A.
      • Fabbian F.
      • et al.
      Outcomes of weekend versus weekday admission for acute aortic dissection or rupture: a retrospective study on the Italian National Hospital Database.
      Meta-analysis of these cohorts found a significantly higher risk of in hospital death in patients treated over the weekend (OR 1.20, 95% CI 1.10 – 1.31, p < .001). The statistical between cohort heterogeneity was moderate (p = .13, I2 = 40%) (Fig. 1B).

      Adjusted in hospital mortality

      Five cohorts comprising of a total of 48 651 patients reported adjusted in hospital mortality data.
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      ,
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      ,
      • Mell M.W.
      • Wang N.E.
      • Morrison D.E.
      • Hernandez-Boussard T.
      Interfacility transfer and mortality for patients with ruptured abdominal aortic aneurysm.
      ,
      • Karthikesalingam A.
      • Holt P.J.
      • Vidal-Diez A.
      • Ozdemir B.A.
      • Poloniecki J.D.
      • Hinchliffe R.J.
      • et al.
      Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.
      Meta-analysis of these cohorts found a significantly greater risk of in hospital death in patients treated over the weekend (OR 1.16, 95% CI 1.09 – 1.23, p < .001). The statistical between cohort heterogeneity was negligible (p = .44, I2 = 0%) (Fig. 1C).

      Unadjusted 90 day mortality

      Two cohorts from a single study comprising of a total of 15 296 patients (3 808 treated over the weekend and 11 488 treated on a weekday) reported unadjusted 90 day mortality data.
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      The study found a greater 90 day mortality risk in patients treated over the weekend, but this was not statistically significant (OR 1.12, 95% CI 0.90 – 1.40, p = .30). The statistical between cohort heterogeneity was considerable (p = .020, I2 = 80%) (Fig. 1D).

      Adjusted 90 day mortality

      One cohort comprising of a total of 9 877 patients reported adjusted 90 day mortality data.
      • Ozdemir B.A.
      • Karthikesalingam A.
      • Sinha S.
      • Poloniecki J.D.
      • Vidal-Diez A.
      • Hinchliffe R.J.
      • et al.
      Association of hospital structures with mortality from ruptured abdominal aortic aneurysm.
      This cohort was noted to have a significantly greater 90 day mortality risk in patients treated over the weekend (OR 1.16, 95% CI 1.04 – 1.29, p = .008) (Fig. 1E).

      Unadjusted 30 day or in hospital or 90 day mortality

      Ten cohorts comprising of a total of 46 422 patients reported unadjusted 30 day or in hospital or 90 day mortality data.
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      ,
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      ,
      • O’Donnell T.F.X.
      • Li C.
      • Swerdlow N.J.
      • Liang P.
      • Pothof A.B.
      • Patel V.I.
      • et al.
      The weekend effect in AAA repair.
      ,
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      • Mell M.W.
      • Wang N.E.
      • Morrison D.E.
      • Hernandez-Boussard T.
      Interfacility transfer and mortality for patients with ruptured abdominal aortic aneurysm.
      • Kózka M.A.
      • Bijak P.
      • Chwala M.
      • Mrowiecki T.
      • Kotynia M.
      • Kaczmarek B.
      • et al.
      The impact of weather factors, moon phases, and seasons on abdominal aortic aneurysm rupture.
      • Groves E.M.
      • Khoshchehreh M.
      • Le C.
      • Malik S.
      Effects of weekend admission on the outcomes and management of ruptured aortic aneurysms.
      • Gallerani M.
      • Imberti D.
      • Bossone E.
      • Eagle K.A.
      • Manfredini R.
      Higher mortality in patients hospitalized for acute aortic rupture or dissection during weekends.
      ,
      • Gallerani M.
      • Volpato S.
      • Boari B.
      • Pala M.
      • De Giorgi A.
      • Fabbian F.
      • et al.
      Outcomes of weekend versus weekday admission for acute aortic dissection or rupture: a retrospective study on the Italian National Hospital Database.
      Meta-analysis of these cohorts found significantly higher mortality in patients treated over the weekend (OR 1.17, 95% CI 1.09 – 1.27, p < .001). The statistical between cohort heterogeneity was moderate (p = .020, I2 = 55%) (Fig. 1F).

      Secondary outcome measures

      Two cohorts comprising of a total of 8 921 patients (2 484 treated over the weekend and 6 437 treated on a weekday) reported data regarding hospital length of stay.
      • Ambler G.K.
      • Mariam N.B.G.
      • Sadat U.
      • Coughlin P.A.
      • Loftus I.M.
      • Boyle J.R.
      • et al.
      Weekend effect in non-elective abdominal aortic aneurysm repair.
      ,
      • Groves E.M.
      • Khoshchehreh M.
      • Le C.
      • Malik S.
      Effects of weekend admission on the outcomes and management of ruptured aortic aneurysms.
      One reported data on hospital length of stay suitable for meta-analysis demonstrating a shorter length of stay for those admitted over the weekend, but the difference was not statistically significant (OR –0.60, 95% CI –1.27 – 0.07, p = .080) (Fig. 1G). The other reported data on prolonged length of hospital stay (defined as being greater than the median value in the dataset) demonstrating a longer length of stay for those admitted over the weekend, but again the difference was not statistically significant (OR 1.06, 95% CI 0.91 – 1.10, p = .48).

      Results of sensitivity and subgroup analysis

      Sensitivity analysis

      Removing one study cohort at a time affected the effect estimate for 90 day mortality only. Removing the English cohort of Karthikesalingam’s 2016 study
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      (leaving one study cohort only in the analysis) demonstrated a statistically significantly increased 90 day mortality in patients treated at a weekend (OR 1.28, 95% CI 1.07 – 1.52, p = .007).
      Removing the study
      • Kózka M.A.
      • Bijak P.
      • Chwala M.
      • Mrowiecki T.
      • Kotynia M.
      • Kaczmarek B.
      • et al.
      The impact of weather factors, moon phases, and seasons on abdominal aortic aneurysm rupture.
      that was judged to be of low methodological quality did not affect the direction of any of the effect estimates.

      Subgroup analysis

      Three cohorts comprising 18 705 patients (4 195 treated over the weekend: 3 646 open, 549 endovascular; 14 510 treated on a weekday: 11 289 open, 3 221 endovascular) reported separate outcome data for open and endovascular interventions, with one reporting in hospital mortality
      • Glance L.G.
      • Osler T.
      • Li Y.
      • Lustik S.J.
      • Eaton M.P.
      • Dutton R.P.
      • et al.
      Outcomes are worse in US patients undergoing surgery on weekends compared with weekdays.
      and the other two 90 day mortality.
      • Karthikesalingam A.
      • Wanhainen A.
      • Holt P.J.
      • Vidal-Diez A.
      • Brownrigg J.R.W.
      • Shpitser I.
      • et al.
      Comparison of long-term mortality after ruptured abdominal aortic aneurysm in England and Sweden.
      Open repair: Of the 18 705 patients included in the subgroup analysis, 14 935 patients underwent open aneurysm repair (3 646 treated over the weekend, 11 289 treated on a weekday). Meta-analysis of these cohorts found a higher mortality risk for those patients treated over the weekend, but this was not statistically significant (OR 1.15, 95% CI 0.94 – 1.40, p = .18). The statistical between cohort heterogeneity was substantial (p = .040, I2 = 69%) (Fig. 2).
      Figure 2
      Figure 2Forest plot of outcomes in patients managed by open aneurysm repair treated over a weekend vs. those treated on a weekday (in hospital mortality for Glance, 90 day mortality for Karthikesalingham). The solid squares denote the odds ratios, the horizontal lines represent the 95% confidence intervals (CI), and the diamond denotes the pooled odds ratio. IV = inverse variance; SE = standard error.
      Endovascular repair: Of the 18 705 patients included in the subgroup analysis, 3 770 patients underwent endovascular aneurysm repair (549 treated over the weekend, 3 221 treated on a weekday). Meta-analysis of these cohorts found a higher mortality risk for those patients treated over the weekend, but this was not statistically significant (OR 1.49, 95% CI 0.74 – 3.00, p = .27). The statistical between cohort heterogeneity was considerable (p = <.001, I2 = 88%) (Fig. 3).
      Figure 3
      Figure 3Forest plot of outcomes in patients managed by endovascular aneurysm repair treated over a weekend vs. those treated on a weekday (in hospital mortality for Glance, 90 day mortality for Karthikesalingham). The solid squares denote the odds ratios, the horizontal lines represent the 95% confidence intervals (CI), and the diamond denotes the pooled odds ratio. IV = inverse variance; SE = standard error.

      Discussion

      Meta-analysis of available data comprising 95 856 patients showed that there was a statistically significant increase in combined unadjusted in hospital and 30 and 90 day all cause mortality in those presenting with rAAA at the weekend compared with those presenting on a weekday. Secondary outcome analysis did not show any significant difference in hospital length of stay between weekday and weekend admissions for rAAA. Subgroup analysis showed a trend towards higher mortality at the weekend for both open and endovascular rAAA repairs; however, statistical significance could not be established for either group, most likely because of the limited data provided by the studies.
      The presence of a weekend effect has been established in multiple studies for several conditions
      • Pauls L.A.
      • Johnson-Paben R.
      • McGready J.
      • Murphy J.D.
      • Pronovost P.J.
      • Wu C.L.
      The weekend effect in hospitalized patients: a meta-analysis.
      • Takagi H.
      • Ando T.
      • Umemoto T.
      ALICE (All-Literature Investigation of Cardiovascular Evidence) group. A meta-analysis of weekend admission and surgery for aortic rupture and dissection.
      • Magid D.J.
      • Wang Y.
      • Herrin J.
      • McNamara R.L.
      • Bradley E.H.
      • Curtis J.P.
      • et al.
      Relationship between time of day, day of week, timeliness of reperfusion, and in-hospital mortality for patients with acute ST-segment elevation myocardial infarction.
      • Ricciardi R.
      • Roberts P.L.
      • Read T.E.
      • Baxter N.N.
      • Marcello P.W.
      • Schoetz D.J.
      Mortality rate after nonelective hospital admission.
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      including ST segment elevation myocardial infarction, acute epiglottitis, and pulmonary embolism. The reasons behind this effect, however, are complex and often debated. One proposed factor leading to the weekend effect is a delay in diagnosis and delay in activation of the treating team;
      • Magid D.J.
      • Wang Y.
      • Herrin J.
      • McNamara R.L.
      • Bradley E.H.
      • Curtis J.P.
      • et al.
      Relationship between time of day, day of week, timeliness of reperfusion, and in-hospital mortality for patients with acute ST-segment elevation myocardial infarction.
      this may be a contributing factor in the case of rAAA due to the requirement for cross sectional imaging for diagnosis and intervention planning, along with the need for a multidisciplinary team for treatment of the condition. Another factor often suggested to contribute to the weekend effect is the lower level of staffing over the weekend.
      • Ricciardi R.
      • Roberts P.L.
      • Read T.E.
      • Baxter N.N.
      • Marcello P.W.
      • Schoetz D.J.
      Mortality rate after nonelective hospital admission.
      In many healthcare systems, the weekend team consists of a skeleton “on call” team covering for urgent and emergency care. This has implications for the entirety of the patient’s management, including delays in diagnosis and pre-operative work up, delays in initiating definitive management, as often only a single theatre team is available over the weekend, as well as implications for post-operative care and recognition of complications in intensive care and on the ward. Another factor which has been suggested to contribute to the weekend effect is that of available level of expertise;
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      this is applicable to the management of rAAA in general but is likely to be more influential for endovascular repair, which requires a more specialist team and equipment. The availability of highly skilled vascular and endovascular surgeons, interventional vascular radiologists and radiographers along with anaesthetists and theatre staff well versed in aortic repair is likely to be less readily available in healthcare systems using a skeleton “on call” team over the weekend.
      The presence of a weekend effect has often been used as an argument for implementation of a seven day equitable healthcare service, including in the UK’s national health service.

      NHS Services, Seven Days a Week. Available at: https://www.england.nhs.uk/wp-content/uploads/2013/12/brd-dec-13.pdf [Accessed 10 April 2020].

      The extent to which services should be expanded has been hotly debated, with some evidence to show that redistributing finite resources to cover seven days does not lead to improvement in outcomes.
      • Gan H.-W.
      • Wong D.J.N.
      • Dean B.J.F.
      • Hall A.S.
      Do expanded seven-day NHS services improve clinical outcomes? Analysis of comparative institutional performance from the “NHS Services, Seven Days a Week” project 2013–2016.
      It can be argued that an equitable seven day service for urgent and emergency conditions such as rAAA, with elective and scheduled care remaining a five day service, may be a workable compromise. This should include routine seven day access to a high quality endovascular service, with the timely provision of expert supporting staff, as recent data show this is the preferred treatment option for rAAA where available and feasible,
      • Kontopodis N.
      • Galanakis N.
      • Antoniou S.A.
      • Tsetis D.
      • Ioannou C.V.
      • Veith F.J.
      • et al.
      Meta-analysis and meta-regression analysis of outcomes of endovascular and open repair for ruptured abdominal aortic aneurysm.
      with the most recent European Society for Vascular Surgery guidelines reflecting this.
      • Wanhainen A.
      • Verzini F.
      • Van Herzeele I.
      • Allaire E.
      • Bown M.
      • Cohnert T.
      • et al.
      Editor’s Choice – European Society for Vascular Surgery (ESVS) 2019 clinical practice guidelines on the management of abdominal aorto-iliac artery aneurysms.

      Agreements and disagreements with other studies or reviews

      Several reviews have been performed looking into the existence of a weekend effect for multiple conditions,
      • Pauls L.A.
      • Johnson-Paben R.
      • McGready J.
      • Murphy J.D.
      • Pronovost P.J.
      • Wu C.L.
      The weekend effect in hospitalized patients: a meta-analysis.
      • Takagi H.
      • Ando T.
      • Umemoto T.
      ALICE (All-Literature Investigation of Cardiovascular Evidence) group. A meta-analysis of weekend admission and surgery for aortic rupture and dissection.
      • Magid D.J.
      • Wang Y.
      • Herrin J.
      • McNamara R.L.
      • Bradley E.H.
      • Curtis J.P.
      • et al.
      Relationship between time of day, day of week, timeliness of reperfusion, and in-hospital mortality for patients with acute ST-segment elevation myocardial infarction.
      • Ricciardi R.
      • Roberts P.L.
      • Read T.E.
      • Baxter N.N.
      • Marcello P.W.
      • Schoetz D.J.
      Mortality rate after nonelective hospital admission.
      • Bell C.M.
      • Redelmeier D.A.
      Mortality among patients admitted to hospitals on weekends as compared with weekdays.
      ,
      • Zhou Y.
      • Li W.
      • Herath C.
      • Xia J.
      • Hu B.
      • Song F.
      • et al.
      Off-hour admission and mortality risk for 28 specific diseases: A systematic review and meta-analysis of 251 cohorts.
      with a higher out of hours mortality rate being established for ST segment elevation myocardial infarction, acute epiglottitis, and pulmonary embolism. Pauls et al.
      • Pauls L.A.
      • Johnson-Paben R.
      • McGready J.
      • Murphy J.D.
      • Pronovost P.J.
      • Wu C.L.
      The weekend effect in hospitalized patients: a meta-analysis.
      found there to be a statistically significantly higher mortality for all hospital admissions over the weekend compared with their weekday counterparts (OR 1.19 95% CI 1.14 – 1.23).
      Two previous meta-analyses have been performed to assess the weekend effect for all aortic aneurysms
      • Zhou Y.
      • Li W.
      • Herath C.
      • Xia J.
      • Hu B.
      • Song F.
      • et al.
      Off-hour admission and mortality risk for 28 specific diseases: A systematic review and meta-analysis of 251 cohorts.
      and all ruptured aortic aneurysms and aortic dissections, with subgroup analysis for rAAA.
      • Takagi H.
      • Ando T.
      • Umemoto T.
      ALICE (All-Literature Investigation of Cardiovascular Evidence) group. A meta-analysis of weekend admission and surgery for aortic rupture and dissection.
      The first of these reviews by Zhou et al.
      • Zhou Y.
      • Li W.
      • Herath C.
      • Xia J.
      • Hu B.
      • Song F.
      • et al.
      Off-hour admission and mortality risk for 28 specific diseases: A systematic review and meta-analysis of 251 cohorts.
      performed a meta-analysis of weekend effect for multiple conditions with aortic aneurysm a subgroup within this, showing a statistically significantly higher all cause mortality over the weekend (OR 1.52, 95% CI 1.30 – 1.77). However, it did not distinguish between anatomical location of aortic aneurysm (TAA vs AAA) or the nature of presentation (elective vs. symptomatic vs. ruptured), factors greatly affecting outcome. In addition, it did not separately assess in hospital, 30 day, and 90 day mortality, instead only using a combined mortality figure. The second of these reviews by Takagi et al.
      • Takagi H.
      • Ando T.
      • Umemoto T.
      ALICE (All-Literature Investigation of Cardiovascular Evidence) group. A meta-analysis of weekend admission and surgery for aortic rupture and dissection.
      performed a meta-analysis for the weekend effect in ruptured aortic aneurysms and dissection with subgroup analysis for rAAA (OR 1.32, 95% CI 1.116 – 1.52; p < .001). The review was limited in that it performed a single meta-analysis for combined mortality rather than the present review which performed separate meta-analyses for in hospital, 30 and 90 day all cause mortality as well as a combined figure. The present review is the largest and most contemporaneous meta-analysis of rAAA, including several studies not included in the above mentioned reviews.

      Limitations

      There are several limitations of the review relating to the data used for meta-analysis. Due to the nature of the research question, all data used were retrospective in nature leading to the potential of confounding factors influencing the conclusions. A large proportion of the data are from studies using national administrative datasets. While these are useful for researchers in allowing them to access large numbers of patient records, they lack clinical detail, including many important peri-operative factors influencing mortality, and can be incorrectly coded which may influence patient outcomes.
      • Bensley R.P.
      • Yoshida S.
      • Lo R.C.
      • Fokkema M.
      • Hamdan A.D.
      • Wyers M.C.
      • et al.
      Accuracy of administrative data versus clinical data to evaluate carotid endarterectomy and carotid stenting.
      For example, no studies in the meta-analysis adjusted for haemodynamic instability at time of presentation, a factor which may influence patient mortality.
      • Wang T.
      • Zhao J.
      • Yuan D.
      • Ma Y.
      • Huang B.
      • Yang Y.
      • et al.
      Comparative effectiveness of open surgery versus endovascular repair for hemodynamically stable and unstable ruptured abdominal aortic aneurysm.
      In addition, many studies did not comment on whether the patient was treated via open surgical procedure or endovascularly which limited the power of the subgroup analysis. The aim was to include as many studies as possible which were relevant to the primary outcome in the meta-analysis. This meant including studies with the weekend effect as a secondary outcome, often limiting the detail provided for analysis. In addition, adjusted ORs were included in the analysis when provided, however, the adjustments made varied between studies. Additionally, variation exists between studies included as to whether patients admitted at a weekend or treated on a weekend were included, and the definition of a “weekend” also differs between studies. The primary outcome was peri-operative mortality; the definition of this varied between studies. To allow power to be added to the conclusion it was decided to include in hospital, 30 and 90 day mortality in the combined analysis.
      One of the major limitations of the review is that of publication bias. An exhaustive review of the literature was undertaken looking into the role of the weekend effect in rAAA; however, the presence of “grey literature”, i.e., data which have not been published and data published in non-commercial form, could result in the possibility that some research data have not been included in the review. In addition, no attempt was made to contact the authors of the included studies to extract further data regarding demographics or outcomes.
      A limitation to the scope of the conclusion from the review is that all the patient cohorts are from North America and Europe, which have, in general, resource rich healthcare systems. These data should therefore be used cautiously in guiding policy in systems with access to moderate to low resource levels. In addition, the data are extracted from studies with recruitment periods ranging from 1988 to 2017. As management of rAAA has changed significantly along with patient outcomes during this period, this may influence the applicability of the results to present day populations. Further to this, no data were collected regarding the differences in resources between weekday and weekend services, and whether this varied between different cohorts based within different healthcare systems. None of the studies reported that they were undertaking their treatments in a seven day equitable vascular service, however the quality of weekend service provision may vary widely between included studies.

      Conclusions

      Implications for practice

      There is an association between weekend admission and higher mortality in patients presenting with rAAAs. Services should be reviewed at both a national and regional level to ensure that high quality emergency vascular care can be provided reliably at the weekend at an equitable level to the weekday service. Implementation of specific management protocols should be illustrated in a multidisciplinary approach, where specialised endovascular, radiological, critical care, and anaesthetic teams are routinely involved in the management of patients with rAAA. Establishment of institutional protocols should involve systemic changes in healthcare delivery infrastructure, with around the clock, seven days a week availability of endovascular devices and auxiliaries, and skilled specialists and nursing teams.

      Implications for research

      Further study into the underlying causes for a weekend effect in rAAA outcomes should be undertaken to attempt to minimise this effect in the future. Analysis of the weekend effect for rAAA comparing outcomes between endovascular and open repair would be beneficial, to allow the optimal management strategy to be offered.

      Conflict of interest

      None.

      Funding

      None.

      Appendix A. Supplementary data

      The following are the Supplementary data to this article:

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      Linked Article

      • Re: “Systemic Review and Meta-Analysis of the Effect of Weekend Admission on Outcomes for Ruptured Abdominal Aortic Aneurysms”
        European Journal of Vascular and Endovascular SurgeryVol. 62Issue 4
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          Leatherby and colleagues remarked that the limitations of their systematic review of the weekend effect on mortality for ruptured abdominal aortic aneurysm were that all the included studies were retrospective and none provided adjustment for haemodynamic instability at the time of presentation.1 Evidence from a prospective study, the IMPROVE trial, compared 30 day mortality for patients presenting in routine working hours vs. out of hours (weekends and nights).2 Overall, patients appeared to have a higher mortality risk when they presented out of hours (adjusted odds ratio [OR] 1.47, 95% CI 1.00 – 2.17): adjustment for age, sex, randomised group, Hardman index, and aneurysm diameter.
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