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Outcomes of Small Incidental Abdominal Aortic Aneurysms in Octogenarian and Nonagenarian Patients in Northern Spain

Open ArchivePublished:June 01, 2021DOI:https://doi.org/10.1016/j.ejvs.2021.03.023

      Objective

      Greater population life expectancy and consistent improvement in diagnostic techniques have increased the diagnosis of abdominal aortic aneurysms (AAAs) in the elderly population. The aim was to study the natural history of small (< 55 mm) incidental AAAs in octogenarian and nonagenarian patients to assess the need for follow up and/or invasive treatment.

      Methods

      This was a retrospective analysis of a prospective registry. Patients ≥ 80 years old at the time of diagnosis of a < 55 mm AAA in 1988–2018 were selected. Clinical and anatomical characteristics were registered. Patients were divided in three groups: 30 – 39 mm, 40 – 49 mm, and 50 – 54 mm AAA. The outcome variables were aorto-iliac rupture, AAA reaching a surgical threshold (≥ 55 mm), and death. A descriptive statistical analysis was performed and life tables, Kaplan–Meier curves, and uni- and multivariable Cox regression were used.

      Results

      Three hundred and ten patients were included, 256 (82.6%) men, with mean index age of 84.5 years (standard deviation [SD] 3.5), and median follow up of 37.9 months (interquartile range [IQR] 18.2 – 65.4). Eighteen (5.8%) AAAs ruptured; four of these patients were operated on and only one survived. Sixty-two (20%) AAA reached a surgical size; eight were repaired electively, with 0% early mortality. The survival rates were 81%, 70%, and 38% at one, two, and five years. The rupture rates were 1%, 2%, and 6% and the AAAs reaching surgical threshold were 1%, 4%, and 19% for the same time periods. AAA size < 40 mm was an independent protective factor from rupture (0.13; 95% confidence interval [CI] 0.03 – 0.48), reaching surgical threshold (0.08; 95% CI 0.04 – 0.16) and death (0.63; 95% CI 0.42 – 0.95).

      Conclusion

      The risk of late rupture of small incidental AAA diagnosed in octogenarian and nonagenarian patients is very small, especially when the AAA is < 40 mm in diameter. In contrast, global mortality is high. Conservative management seems sensible, with strict selection of the patients who would benefit from follow up and eventual repair.

      Keywords

      This study describes a large cohort of octogenarian and nonagenarian patients with small incidental abdominal aortic aneurysms (AAA). Rupture risk was very low, especially in AAAs smaller than 40 mm. AAAs closer to 55 mm at baseline often reach the surgical threshold but are usually managed conservatively due to life expectancy and comorbidity. The findings suggest that the discontinuation of surveillance in the smallest AAAs seems safe. Careful early assessment of fitness, life expectancy, functionality, surgical risk, anatomical feasibility for endovascular aneurysm repair and joint informed decision making would help select the patients with larger AAAs who would benefit from follow up and eventual elective repair, thus unburdening local and national healthcare systems from unnecessary AAA surveillance in selected elderly patients.

      Introduction

      The natural history of small abdominal aortic aneurysms (AAAs) is for progressive and mostly interrupted growth,
      • Vega de Céniga M.
      • Gómez R.
      • Estallo L.
      • de la Fuente N.
      • Viviens B.
      • Barba A.
      Analysis of expansion patterns in 4-4.9 cm abdominal aortic aneurysms.
      with estimated rates of 1.3 mm/year for 30 mm AAA and 3.6 mm/year for 50 mm AAA.
      • Bown M.J.
      • Sweeting M.J.
      • Brown L.C.
      • Powell J.T.
      • Thompson S.G.
      RESCAN collaborators
      Surveillance intervals for small abdominal aortic aneurysms: a meta-analysis.
      The most recent European Society for Vascular Surgery (ESVS) guidelines on the management of aorto-iliac aneurysms recommend ultrasonography surveillance for 30 – 55 mm asymptomatic AAA, with a three or more year interval for 30 – 39 mm AAA, annual follow up for 40 – 49 mm AAA, and every three to six months for ≥ 50 mm AAA.
      • Bown M.J.
      • Sweeting M.J.
      • Brown L.C.
      • Powell J.T.
      • Thompson S.G.
      RESCAN collaborators
      Surveillance intervals for small abdominal aortic aneurysms: a meta-analysis.
      ,
      • Wanhainen A.
      • Verzini F.
      • Van Herzeele I.
      • Allaire E.
      • Bown M.
      • Cohnert T.
      • et al.
      European Society for Vascular Surgery (ESVS) 2019 clinical practice guidelines on the management of abdominal aorto-iliac artery aneurysms.
      The threshold for elective AAA repair is recommended at ≥ 55 mm in men, with a class I recommendation supported by high quality and extensive evidence, and ≥ 50 mm in women with acceptable surgical risk (class IIb recommendation).
      • Wanhainen A.
      • Verzini F.
      • Van Herzeele I.
      • Allaire E.
      • Bown M.
      • Cohnert T.
      • et al.
      European Society for Vascular Surgery (ESVS) 2019 clinical practice guidelines on the management of abdominal aorto-iliac artery aneurysms.
      ,
      • Filardo G.
      • Powell J.T.
      • Martínez M.A.
      • Ballard D.J.
      Surgery for small abdominal aortic aneurysms.
      The indication is based on assessment of AAA rupture risk, basically related to diameter, surgical risk, and life expectancy.
      • Bown M.J.
      • Sweeting M.J.
      • Brown L.C.
      • Powell J.T.
      • Thompson S.G.
      RESCAN collaborators
      Surveillance intervals for small abdominal aortic aneurysms: a meta-analysis.
      ,
      • Grootenboer N.
      • van Sambeek M.R.
      • Arends L.R.
      • Hendriks J.M.
      • Hunink M.G.
      • Bosch J.L.
      Systematic review and meta-analysis of sex differences in outcome after intervention for abdominal aortic aneurysm.
      ,
      • Ulug P.
      • Sweeting M.J.
      • von Allmen R.S.
      • Thompson S.G.
      • Powell J.T.
      Morphological suitability for endovascular repair, non-intervention rates, and operative mortality in women and men assessed for intact abdominal aortic aneurysm repair: systematic reviews with meta-analysis.
      The reduction in AAA related and all cause mortality associated with population screening in men was established in several trials conducted in the UK, Denmark, and Australia, with number needed to screen of 667 and number needed to treat of 1.5.
      • Cosford P.A.
      • Leng G.C.
      Screening for abdominal aortic aneurysm.
      ,
      • Wanhainen A.
      • Hultgren R.
      • Linné A.
      • Holst J.
      • Gottsäter A.
      • Langenskiöld M.
      • et al.
      Outcome of the Swedish nationwide abdominal aortic aneurysm screening programme.
      Therefore, population screening for AAA with a single ultrasound (US) scan is recommended for all men at age 65 years.
      • Wanhainen A.
      • Verzini F.
      • Van Herzeele I.
      • Allaire E.
      • Bown M.
      • Cohnert T.
      • et al.
      European Society for Vascular Surgery (ESVS) 2019 clinical practice guidelines on the management of abdominal aorto-iliac artery aneurysms.
      National population screening for AAA in 65 year old men has been implemented in the UK, Sweden, Italy, and the United States.
      • Wanhainen A.
      • Hultgren R.
      • Linné A.
      • Holst J.
      • Gottsäter A.
      • Langenskiöld M.
      • et al.
      Outcome of the Swedish nationwide abdominal aortic aneurysm screening programme.
      • Sweeting M.J.
      • Thompson S.G.
      • Brown L.C.
      • Powell J.T.
      RESCAN collaborators
      Meta-analysis of individual patient data to examine factors affecting the growth and rupture of abdominal aortic aneurysms.
      • Jacomelli J.
      • Summers L.
      • Stevenson A.
      • Lees T.
      • Earnshaw J.J.
      Results of the first five years of the NHS abdominal aortic aneurysm screening programme in England.
      A similar screening programme in women is unlikely to be cost effective and is not currently recommended.
      • Sweeting M.J.
      • Masconi K.L.
      • Jones E.
      • Ulug P.
      • Glover M.J.
      • Michaels J.A.
      • et al.
      Analysis of clinical benefit, harms, and cost-effectiveness of screening women for abdominal aortic aneurysm.
      The majority of AAAs detected in screening programmes are < 40 mm, and enter long term surveillance programmes.
      • Darwood R.
      • Earnshaw J.J.
      • Turton G.
      • Shaw E.
      • Whyman M.
      • Poskitt K.
      • et al.
      Twenty-year review of abdominal aortic aneurysm screening in men in the county of Gloucestershire, United Kingdom.
      ,
      • Oliver-Williams C.
      • Sweeting M.J.
      • Jacomelli J.
      • Summers L.
      • Stevenson A.
      • Lees T.
      • et al.
      Safety of men with small and medium abdominal aortic aneurysms under surveillance in the NAAASP.
      The widespread use of imaging techniques has also increased the number of incidental AAA detections in all ages.
      The number of people aged 80 years or over is projected to triple in the world, from 143 million in 2019 to 426 million in 2050. With increasing life expectancy, both screen detected and incidentally diagnosed AAAs add up to an increasing number of cases in this older population. Specific data on > 80 year old patients are scarce. Shorter life expectancy in the octogenarian and nonagenarian population can question the benefit of elective AAA repair. Prevention of AAA rupture and death must be strictly balanced against surgical risk and interference with quality of life in these patients. The benefit of follow up in the elderly population is unclear, especially if they would not be considered fit for an elective repair.
      The aim was to study the natural history of small (< 55 mm) incidental AAAs in octogenarian and nonagenarian patients in the local healthcare area to assess the need for follow up and/or invasive treatment.

      Patients and Methods

      A retrospective study of a prospective cohort of AAA patients was performed. The patients were selected from a registry which collects all consecutive patients diagnosed with an AAA in the healthcare area covered by the Hospital of Galdakao-Usansolo (OSI Barrualde) since its opening in 1988. Patients enter the surveillance programme and database through referral of any AAA incidentally found on any imaging technique, screening for AAA on peripheral arterial disease (PAD) patients,
      • Barba A.
      • Estallo L.
      • Rodríguez L.
      • Baquer M.
      • Vega de Ceniga M.
      Detection of abdominal aortic aneurysm in patients with peripheral artery disease.
      and yearly cross checking all diagnostic codes of AAA on any report (admission, radiology) within the healthcare area archive. All patients sign informed consent to be included in this database on first consultation, and all database analysis projects are assessed by the hospital’s ethics committee.
      The selection criteria for this study were patients of age 80 years or older at the time of the diagnosis of a < 55 mm infra/juxta/suprarenal AAA, between January 1988 and December 2018. Patients with thoraco-abdominal AAAs were excluded. Patients already under surveillance for a small AAA diagnosed at age < 80 were excluded to avoid introducing the confounding variable of vascular intervention (prescription of aspirin and statins, cardiovascular optimisation), with variable intensity of effect depending on the previous length of this medical treatment, which could potentially impact outcome (cardiovascular events, death) in a subset of the patients, thus introducing selection bias.
      Demographic data (age and gender); cardiovascular risk factors (smoking history, hypertension, diabetes mellitus [DM], hypercholesterolaemia); cardiac, respiratory, and renal comorbidity, cerebrovascular and peripheral arterial disease, neoplasia; AAA characteristics (location, symptoms); sequential AAA diameters (mm) from baseline to last follow up measurement; AAA repair; AAA rupture; and death and cause of death were registered prospectively.
      The following were considered: history of smoking as current and previous smoking habit; arterial hypertension when the patient reported a physician diagnosis and/or was taking hypotensive medication; DM when the patient reported a physician diagnosis and/or was being treated with a specific diet, oral hypoglycaemic agents and/or insulin, or if the following were found: basal glycaemia > 126 mg/dL and/or HbA1c ≥ 6.5% in the baseline study; and hypercholesterolaemia when the patient had total cholesterol level > 200 mg/dL, LDL > 100 mg/dL and/or was taking specific medication or under a supervised diet.
      Heart disease was defined as coronary artery disease, defined as a positive history of angina pectoris, myocardial infarction and/or percutaneous revascularisation or coronary bypass grafting, valvular disease, history of heart failure, myocardiopathy (ischaemic, alcoholic, idiopathic), and/or arrythmia; chronic pulmonary obstructive disease (COPD) when the patient had been thus diagnosed by a respiratory physician and received treatment and/or surveillance; and chronic renal disease (CRD) when creatinine concentration was > 1.5 mg/dL and/or glomerular filtration rate < 60 mL/min/1.73 m2; cerebrovascular disease as a previous transient ischaemic attack and/or minor or major stroke and/or > 50% carotid artery stenosis; PAD as previous or current symptoms of intermittent claudication or critical limb ischaemia, absence of distal pulses in the lower limbs and ankle brachial index < 0.8 in one or both lower limbs; and neoplasia as a previous or active personal history of any kind of cancer (including concomitant diagnosis at the time of incidental diagnosis of the AAA).
      The cohort registry covers 30 years. Initially, the surveillance protocol included a yearly US scan for 30 – 40 mm AAA and six monthly alternating US and computed tomography (CT) scans for 40 – 50/55 mm. In the last decade, in the light of the published evidence, the protocol was changed to US scanning every two years for 30 – 39 mm AAA, yearly US examination for 40 – 49 mm AAA, and alternating US and CT scans every six months for 50 – 54 mm. Up to 2007, US and CT measurements were made by the hospital radiologists. Since 2007, the diagnostic and follow up US scans have been performed in the Vascular Surgery Department, using leading edge to leading edge anteroposterior diameter in systole, trying to get the roundest image plane. The centreline outer to outer AAA diameter in CT scans was measured.
      • Schäberle W.
      • Leyerer L.
      • Schierling W.
      • Pfister K.
      Ultrasound diagnostics of the abdominal aorta.
      Whenever possible, the initial AAA diameter was confirmed, regardless of the size, with a CT scan, with complete assessment of the thoraco-abdominal aorta and the iliac axis. The threshold for consideration of elective repair was 50 mm from 1988 to 2008, and 55 mm thereafter. Endovascular aneurysm repair (EVAR) has been available in the centre since 2004.
      All patients were followed until death or 30 March 2020. All deaths are confirmed periodically through the healthcare (hospital and primary care) records and the civil registry, for date and cause of death.
      The outcome variables were aorto-iliac rupture, confirmed by US or CT scan or death certificate; AAA growth to ≥ 55 mm, the currently recommended threshold for elective repair; and death from any cause.
      The findings are described as mean (standard deviation [SD]; range) or median (interquartile [IQR]) values for continuous variables and numbers (%) for categorical variables. Uni- and multivariable statistical analysis were performed with life tables, Kaplan–Meier curves, and Cox regression. The cohort was stratified in two groups according to gender and in three groups according to the baseline AAA diameter: 30 – 39 mm, 40 – 49 mm, 50 – 54 mm. Multivariable analysis was adjusted by age, gender, and any other variable which obtained p < .20 in univariable analysis. SPSS 20.0 (http://www.spss.com/) was used and p < .050 was considered to be statistically significant.

      Results

      Three hundred and ten patients were included in the study. The number of small AAA diagnosed in this population has increased from eight in the period 1988 – 1993 to 70 in the last quinquennium (2014 – 2018) (Fig. 1). Thirty-five AAA (11.3%) were detected through screening of PAD patients. The incidental detection of the rest is detailed in Fig. 2.
      Figure 1
      Figure 1Numbers of diagnoses of small abdominal aortic aneurysms (AAAs) in the cohort of ≥ 80 year old patients from 1988 to 2018 in the Hospital of Galdakao-Usansolo in Spain.
      Figure 2
      Figure 2Sources of diagnosis of the 310 abdominal aortic aneurysms (AAAs) in ≥ 80 year old patients.
      The baseline clinical characteristics of the cohort are detailed in Table 1. Briefly, it included 256 (82.6%) men and 54 (17.4%) women, the mean age was 84.5 years, ranging from 80 to 96 years. There was high prevalence of comorbidities, with 51.9% heart disease, 32.9% COPD, 20% – 25% CRD, PAD, cerebrovascular disease or neoplasia.
      Table 1Clinical characteristics of the cohort of ≥ 80 year old patients with small (< 55 mm) incidental abdominal aortic aneurysms
      CharacteristicsOverall (n = 310)Baseline abdominal aortic aneurysm diameter
      30–39 mm (n = 159)40–49 mm (n = 114)50–54 mm (n = 37)
      Age – y84.5 ± 3.584.3 ± 3.284.8 ± 3.884.6 ± 3.5
      Male gender256 (82.6)128 (80.5)98 (86)30 (81.1)
      Cardiovascular risk factors
       Smoking181 (58.3)88 (55.3)71 (62.3)22 (59.5)
       Arterial hypertension204 (65.8)100 (62.9)76 (66.7)28 (75.7)
       Diabetes mellitus39 (12.6)22 (13.8)13 (11.4)4 (10.8)
       Hypercholesterolaemia118 (38.1)58 (36.5)47 (41.2)13 (35.1)
      Comorbidity
       Heart disease161 (51.9)73 (45.9)64 (56.1)24 (64.9)
       COPD102 (32.9)54 (34)36 (31.6)12 (32.4)
       CRD72 (23.2)28 (17.6)30 (26.3)14 (37.8)
       Cerebrovascular disease68 (21.9)27 (17)32 (28.1)9 (24.3)
       PAD79 (25.5)49 (30.8)21 (18.4)9 (24.3)
       Neoplasia77 (24.8)38 (23.9)32 (28.1)7 (18.9)
      Data are presented as n (%) or mean ± standard deviation. COPD = chronic obstructive pulmonary disease; CRD = chronic renal disease; PAD = peripheral arterial disease.
      Most AAA (296; 95.5%) were infrarenal, six (1.9%) were juxtarenal, and eight (2.6%) were suprarenal. Only five (1.6%) were symptomatic (one contained ruptured 50 mm AAA, one 35 mm inflammatory AAA with abdominal and lumbar pain, three 37 – 40 mm AAA with ruptured common iliac aneurysms). The mean AAA diameter was 39.2 mm (SD 6.7; range 30 – 54 mm). This diameter was obtained from a CT scan in 266 (85.8%) patients and from US in 44 (14.2%). According to their baseline diameter they could be classified into three groups: 159 (51.3%) in the 30 – 39 mm, Group 1; 114 (36.8%) in the 40 – 49 mm, Group 2; and 37 (11.9%) in the 50 – 54 mm, Group 3.
      The median follow up of the patients was 37.9 months (IQR 18.2 – 65.4). Only one patient (0.3%) was lost to follow up, giving a follow up index (FUI) of 0.997. By the end of the study 245 (79%) patients had died. Overall survival was 81%, 70%, 38%, and 21% at 1, 2, 5, and 7 years (Fig. 3A). The main causes of death were baseline comorbid conditions, with aorto-iliac rupture accounting for only 15 (6.1%) of the deaths (Table 2). Three autopsies were registered: one because of suicide, one trauma, and one cardiac sudden death.
      Figure 3
      Figure 3Life tables of (A) survival, (B) abdominal aortic aneurysm (AAA) rupture, and (C) AAA growth reaching ≥ 55 mm in the cohort of 310 ≥ 80 year old patients with AAA.
      Table 2Causes of death (n = 245) in the cohort
      Cause of deathPatients (n = 245)
      Cardiac
      Cardiomyopathy, myocardial infarction, endocarditis, heart failure.
      51 (20.8)
      Dementia41 (16.7)
      Neoplasia
      Lung, colon, prostate, lymphoma, renal, gall bladder, ureter, bladder, oesophagus, stomach, liver, melanoma, myeloma, pancreas.
      38 (15.5)
      Respiratory
      Infection, pulmonary fibrosis, chronic obstructive pulmonary disease.
      26 (10.6)
      Digestive
      Ischaemic colitis, haemorrhage, cirrhosis, mesenteric ischaemia, acute pancreatitis.
      24 (9.8)
      Aorto-iliac rupture15 (6.1)
      Sepsis
      Urinary, respiratory, peritoneal.
      12 (4.9)
      Neurological
      Stroke, brain haemorrhage.
      11 (4.5)
      Renal
      Acute renal failure, chronic renal failure.
      10 (4.1)
      Vascular (except aorto-iliac rupture)
      Thoracic aortic rupture, acute limb ischaemia, critical limb threatening ischaemia, femoral aneurysm rupture.
      9 (3.7)
      Other
      Suicide, trauma, coagulopathy.
      5 (2.1)
      Unknown3 (1.2)
      Data are presented as n (%).
      Cardiomyopathy, myocardial infarction, endocarditis, heart failure.
      Lung, colon, prostate, lymphoma, renal, gall bladder, ureter, bladder, oesophagus, stomach, liver, melanoma, myeloma, pancreas.
      Infection, pulmonary fibrosis, chronic obstructive pulmonary disease.
      § Ischaemic colitis, haemorrhage, cirrhosis, mesenteric ischaemia, acute pancreatitis.
      Urinary, respiratory, peritoneal.
      Stroke, brain haemorrhage.
      ∗∗ Acute renal failure, chronic renal failure.
      †† Thoracic aortic rupture, acute limb ischaemia, critical limb threatening ischaemia, femoral aneurysm rupture.
      ‡‡ Suicide, trauma, coagulopathy.
      Eighteen (5.8%) AAA ruptured during the follow up period, for an incidence of 1%, 2%, 6%, and 12% at 1, 2, 5, and 7 years (Fig. 3B). Only four (2.5%) AAAs with an index diameter < 40 mm ruptured during follow up, eight (7%) among the baseline 40 – 49 mm, and five (13.5%) of the baseline 50 – 54 mm AAA. The median diameter at the time of rupture was 68 mm (IQR 50 – 79). Four patients were operated on and only one survived, one patient had a contained rupture and remains alive 10 months later, and another patient had a contained rupture and died two months later due to acute pancreatitis, resulting in a mortality of 83.3% (n = 15) after AAA rupture.
      Sixty-two (20%) AAAs reached a surgical diameter (≥ 55 mm) during follow up, for an incidence of 1%, 4%, 19%, and 32% after 1, 2, 5, and 7 years (Fig. 3C). Eleven (6.9%) AAAs with index diameter < 40 mm reached the threshold diameter, 29 (25.4%) among the baseline 40 – 49 mm, and 20 (54.1%) of the baseline 50 – 54 mm. Fifty-seven (91.9%) were managed conservatively: 25 because they were deemed high risk of open repair and they had hostile anatomy for standard EVAR, 20 because elective repair was considered contraindicated due to dementia or terminal illness, 11 because of patient refusal, and one because it was < 55 mm in diameter at the last assessment, the patient did not comply with the follow up visits for six years and eventually arrived at the emergency room with a ruptured AAA. Thirteen of these AAA ruptured, two (18.2%) among the patients who had turned down elective repair, 11 (23.9%) among the rest. One patient awaits elective EVAR. The other four patients, and four additional patients with < 55 mm AAA (indicated in the initial years when threshold for elective repair was placed at 50 mm or because of large iliac aneurysms) were repaired electively, five with an open surgical procedure and three with EVAR, with a 0% 30 day mortality rate. As additional data, during the same study period, 87 intact AAA were diagnosed with a baseline diameter ≥ 55 mm in ≥ 80 year old patients. Twelve of them (14%) were repaired electively, with a 30 day mortality of 25% (n = 3, all open repairs). During follow up, 21 of the 75 unrepaired AAA (28%) ruptured.
      Long term survival was significantly greater among women than men (p = .045) in univariable analysis. Rates of AAA rupture and AAA growth to a surgical diameter were similar among men and women (p > .50).
      Survival was significantly higher among patients with the smallest (30 – 39 mm) AAA (p = .004). Rates of AAA rupture and growth to a surgical diameter were significantly lower in 30 – 39 mm AAA (p = .005 and < .001 respectively).
      Multivariable analysis showed 30 – 39 mm AAA diameter to be an independent protective factor against late death, in contrast to age, heart disease, PAD, diabetes, COPD, and neoplasia, which were independent risk factors. Gender did not prove to be an independent factor affecting survival. Smaller AAA size was also an independent protective factor against AAA rupture and AAA growth to a surgical diameter (Table 3).
      Table 3Multivariable analysis of risk factors for mortality, abdominal aortic aneurysm (AAA) rupture and AAA growth to threshold diameter (≥ 55 mm) in ≥80-year-old patients
      HR (95% CI)p
      Mortality
      AAA diameter – mm
      30–390.63 (0.42–0.95).026
      40–491.02 (0.68–1.55).91
      50–541.00
       Heart disease1.42 (1.09–1.83).008
       PAD1.67 (1.26–2.23)<.001
       Age per one year increment1.10 (1.06–1.15)<.001
       Diabetes mellitus1.55 (1.06–2.27).024
       COPD1.65 (1.24–2.20).001
       Neoplasia1.43 (1.06–1.91).018
       Female gender1.19 (0.83–1.73).41
       Chronic renal failure0.96 (0.70–1.30).77
       Cerebrovascular disease0.98 (0.72–1.34).91
      AAA rupture
      AAA diameter – mm
      30–390.13 (0.03–0.48).002
      40–490.51 (0.17–1.56).24
      50–541.00
       Heart disease2.62 (0.87–7.94).09
       PAD0.62 (0.14–2.82).53
       Age1.04 (0.88–1.22).66
       Gender1.90 (0.55–6.57).31
      AAA growth to ≥55 mm
      AAA diameter – mm
      30–390.08 (0.04–0.16)< .001
      40–490.58 (0.32–1.05).071
      50–541.00
       Heart disease0.81 (0.46–1.44).48
       PAD1.47 (0.72–2.99).29
       Age0.97 (0.88–1.08).62
       Gender1.02 (0.50–2.05).96
       Chronic renal failure0.84 (0.45–1.54).57
      HR = hazard ratio; CI = confidence interval; PAD = peripheral arterial disease; COPD = chronic obstructive pulmonary disease.

      Discussion

      This study followed 310 patients aged 80 or older with a first time incidental diagnosis of a < 55 mm AAA. Late rupture and growth to a threshold diameter were rare (2.5% and 6.9%) among AAAs with a baseline diameter < 40 mm, with higher rates of 7% and 25.4% and 13.5% and 54.1% for 40 – 49 mm and 50 – 54 mm AAA respectively. Late mortality was 79% by the end of the study, with only 6.1% AAA related deaths.
      The increasing number of octogenarians and nonagenarians in countries, and their ever improving physical, cognitive, and functional situation, pose a dilemma for the management of their asymptomatic AAA. In the Basque country, currently 7.2% of the population is ≥ 80 years. AAA prevalence remains high, 4.7% in 65 year old men in 2008, with a delay in the decline observed in Northern Europe and the United States.
      • Barba A.
      • Vega de Ceniga M.
      • Estallo L.
      • de la Fuente N.
      • Viviens B.
      • Izagirre M.
      Prevalence of AAA is still high in certain areas of Southern Europe.
      ,
      • Lederle F.A.
      The rise and fall of abdominal aortic aneurysm.
      These two factors, together with the increase in imaging studies in all medical areas, help explain the increasing detection of AAAs in the last few years.
      Average life expectancy in the Basque country is currently 80.6 years for men and 86.4 years for women. Many of the patients in this cohort already exceeded this life expectancy at baseline. Thus, midterm survival was poor, with 70% alive after two years but less than 40% after five years. Elbasty’s cohort of 101 AAA patients aged 85 – 89 described 25.7% mortality after a median follow up of 56 months.
      • Elbasty A.
      • Nickinson A.T.O.
      • Delaney C.
      • Stather P.W.
      • Burrows M.
      • Delbridge M.
      • et al.
      Outcomes of sub-threshold abdominal aortic aneurysms undergoing surveillance in patients aged 85 years or over.
      A study derived from the Swedvasc registry observed a higher relative survival rate than their age matched general population counterparts in ≥ 80 year old patients after successful AAA repair, with a notable improvement since 2000, which could reflect a good selection of the fittest octogenarian patients to benefit from elective AAA repair.
      • Mani K.
      • Björck M.
      • Lundkvist J.
      • Wanhainen A.
      Improved long-term survival after abdominal aortic aneurysm repair.
      In contrast, the present cohort includes all elderly AAA patients, not only those selected for elective repair but also the sicker ones managed conservatively, which probably impacted overall survival. This offers a more complete picture of the prognosis of this elderly population, an important aspect when deciding on the clinical benefit and cost effectiveness of surveillance and invasive management.
      The objective of follow up and eventual elective repair of AAA is to prevent rupture and subsequent death. Rupture rates for small AAAs are low, ranging from 0 to 1.61 ruptures/100 person years.
      • Powell J.T.
      • Gotensparre S.M.
      • Sweeting M.J.
      • Brown L.C.
      • Fowkes F.G.R.
      • Thompson S.G.
      Rupture rates of small abdominal aortic aneurysms: a systematic review of the literature.
      A recent report from the UK National Health Service AAA Screening Programme (NAAASP) described rupture rates of 0.03% per annum for 30 – 44 mm AAA, and 0.28% for 45 – 54 mm AAA.
      • Oliver-Williams C.
      • Sweeting M.J.
      • Jacomelli J.
      • Summers L.
      • Stevenson A.
      • Lees T.
      • et al.
      Safety of men with small and medium abdominal aortic aneurysms under surveillance in the NAAASP.
      In the RESCAN study, for 3 – 4.5 cm and 5 cm AAA the average time to reach a 1% rupture risk was at least two years and 1.4 years respectively.
      • Bown M.J.
      • Sweeting M.J.
      • Brown L.C.
      • Powell J.T.
      • Thompson S.G.
      RESCAN collaborators
      Surveillance intervals for small abdominal aortic aneurysms: a meta-analysis.
      Older age has been described to increase the AAA rupture risk.
      • Sweeting M.J.
      • Thompson S.G.
      • Brown L.C.
      • Powell J.T.
      RESCAN collaborators
      Meta-analysis of individual patient data to examine factors affecting the growth and rupture of abdominal aortic aneurysms.
      In the present cohort the total incidence of AAA rupture of 5.8% was found at a mean follow up of 3.6 years. For < 40 mm AAA, rupture occurred in 2.3% at five years, when the overall survival of the cohort was 38%. In Elbasty’s study, 11.5% of the deaths in the octogenarian patients were AAA related with no ruptures observed in AAA with an index diameter 30 – 50 mm.
      • Elbasty A.
      • Nickinson A.T.O.
      • Delaney C.
      • Stather P.W.
      • Burrows M.
      • Delbridge M.
      • et al.
      Outcomes of sub-threshold abdominal aortic aneurysms undergoing surveillance in patients aged 85 years or over.
      The rupture rates of 40 – 49 mm and 50 – 54 mm AAA were 1.9% and 6.5% respectively at two years and 10.2% and 19% at five years in the cohort. In Elbasty’s study, 6.8% of 50 – 54 mm AAA ruptured during follow up, cases which had reached threshold diameters but were unfit for repair.
      • Elbasty A.
      • Nickinson A.T.O.
      • Delaney C.
      • Stather P.W.
      • Burrows M.
      • Delbridge M.
      • et al.
      Outcomes of sub-threshold abdominal aortic aneurysms undergoing surveillance in patients aged 85 years or over.
      A careful selection of patients who can benefit from AAA surveillance, and eventual elective repair, can significantly unburden the healthcare resources. Both the 2019 ESVS guidelines and the 2020 NICE guidelines on the management of aorto-iliac aneurysms do not qualify their surveillance recommendations for different age groups,
      • Wanhainen A.
      • Verzini F.
      • Van Herzeele I.
      • Allaire E.
      • Bown M.
      • Cohnert T.
      • et al.
      European Society for Vascular Surgery (ESVS) 2019 clinical practice guidelines on the management of abdominal aorto-iliac artery aneurysms.
      ,
      NICE guideline
      Abdominal aortic aneurysm: diagnosis and management.
      but the needs and indications differ according to health status and life expectancy. The EVAR II trial concluded that elective EVAR of AAA in frail patients did not improve all cause or AAA related mortality rates, but increased hospital costs.
      EVAR Trial participants. Endovascular aneurysm repair and outcome in patients unfit for open repair of abdominal aortic aneurysm (EVAR trial 2): randomised controlled trial.
      Although this trial was not targeted specifically to > 80 year old patients, these can also be considered a frail, high risk population for open repair. Follow up of < 40 mm AAA seems unnecessary in the vast majority of elderly patients. For larger AAA, early assessment of life expectancy, fitness, comorbidity, rupture risk, and patient preferences can help in the selection. This and previous studies
      • Elbasty A.
      • Nickinson A.T.O.
      • Delaney C.
      • Stather P.W.
      • Burrows M.
      • Delbridge M.
      • et al.
      Outcomes of sub-threshold abdominal aortic aneurysms undergoing surveillance in patients aged 85 years or over.
      can help guide future targeted recommendations for this subpopulation.
      The risk of AAA rupture has been estimated to be four times higher in women than men for all AAA diameters
      • Bown M.J.
      • Sweeting M.J.
      • Brown L.C.
      • Powell J.T.
      • Thompson S.G.
      RESCAN collaborators
      Surveillance intervals for small abdominal aortic aneurysms: a meta-analysis.
      ,
      • Grootenboer N.
      • van Sambeek M.R.
      • Arends L.R.
      • Hendriks J.M.
      • Hunink M.G.
      • Bosch J.L.
      Systematic review and meta-analysis of sex differences in outcome after intervention for abdominal aortic aneurysm.
      ,
      • Ulug P.
      • Sweeting M.J.
      • von Allmen R.S.
      • Thompson S.G.
      • Powell J.T.
      Morphological suitability for endovascular repair, non-intervention rates, and operative mortality in women and men assessed for intact abdominal aortic aneurysm repair: systematic reviews with meta-analysis.
      and the time estimated to reach a 1% rupture risk was significantly shorter in women in the RESCAN study.
      • Bown M.J.
      • Sweeting M.J.
      • Brown L.C.
      • Powell J.T.
      • Thompson S.G.
      RESCAN collaborators
      Surveillance intervals for small abdominal aortic aneurysms: a meta-analysis.
      There were no significant differences in the rupture risk between elderly men and women in the study, but the sample size, with only 54 women, is probably too small to detect this difference. The registry participated in the RESCAN study, which highlighted the increase in rupture risk, so it is probably large cohorts that can make these differences measurable. On the other hand, those differences in risk between men and women might be so for all ages, but specifically not for this precise age range; this remains to be proved.
      The rates of the AAA reaching 55 mm were calculated as the surgical threshold. However, in this older population, the threshold to consider an elective procedure could be larger. As stated in the 2020 NICE guidelines, the management decision for a patient with unruptured AAA must be based on “the overall balance of benefits and risks with repair and with conservative management, based on their current and expected future health”
      NICE guideline
      Abdominal aortic aneurysm: diagnosis and management.
      and this balance will differ in a > 80 year old patient compared with a younger one. Only 4% of the AAA in the cohort reached a 55 mm diameter at two years, 19% at five years, with an anecdotal 2.9% at five years for baseline 30 – 39 mm AAA. Almost a quarter of the 50 – 54 mm AAA reached a potentially surgical diameter by two years and almost two thirds by five years. According to the RESCAN study, a 3 cm AAA required an estimated 7.4 years to have a 10% chance of reaching 5.5 cm2. The estimated required time was 3.2 years for 4 cm AAA, and 0.7 years for 5 cm AAA.
      • Bown M.J.
      • Sweeting M.J.
      • Brown L.C.
      • Powell J.T.
      • Thompson S.G.
      RESCAN collaborators
      Surveillance intervals for small abdominal aortic aneurysms: a meta-analysis.
      A third of the 3 – 3.9 cm AAA detected through screening in Gloucestershire, UK, had reached 5.5 cm at a median of 6.3 years; it was 50% for the 4 – 5.4 cm AAA, with a median time of 21 months.
      • Darwood R.
      • Earnshaw J.J.
      • Turton G.
      • Shaw E.
      • Whyman M.
      • Poskitt K.
      • et al.
      Twenty-year review of abdominal aortic aneurysm screening in men in the county of Gloucestershire, United Kingdom.
      In the more recent report from NAAASP, 9.5% of the patients with 30 – 54 mm screened AAA reached a ≥ 55 mm diameter during the surveillance program.
      • Oliver-Williams C.
      • Sweeting M.J.
      • Jacomelli J.
      • Summers L.
      • Stevenson A.
      • Lees T.
      • et al.
      Safety of men with small and medium abdominal aortic aneurysms under surveillance in the NAAASP.
      In Elbasty’s study, 3.4% of the 30 – 39 mm AAA, 11.6% of the 40 – 45 mm AAA and 75.9% of the > 50 mm AAA reached the threshold size during follow up.
      • Elbasty A.
      • Nickinson A.T.O.
      • Delaney C.
      • Stather P.W.
      • Burrows M.
      • Delbridge M.
      • et al.
      Outcomes of sub-threshold abdominal aortic aneurysms undergoing surveillance in patients aged 85 years or over.
      Both Elbasty’s and this study address the same profile of patients in two different populations, in Northern and Southern Europe, and show similar results, which scientifically reinforces the findings and interpretation. These elderly patients should receive early and careful assessment of physical and functional fitness and life expectancy, to foresee potential eventual benefit from prophylactic aortic surgery and decide on an active surveillance plan tailored to the patients’ needs, or conversely to end surveillance if no net benefit is foreseen.
      This study is limited by its retrospective nature and the lack of autopsies to ensure the cause of death in some cases. These unclear cases are however few (three unknown, 41 deemed dementias as the cause of death with no symptoms suggestive of aorto-iliac rupture) and would not substantially change the results or the conclusions that can be drawn from them. The cohort is large, with systematic inclusion of all diagnosed patients, with low risk of selection bias. The number of women is small and might limit the possibility of accurately assessing gender differences. A small number of AAA did not have a baseline CT scan, and US measurement can convey a ± 2 – 4 mm margin of error. The cohort spans 30 years, in which surgical thresholds and medical management have changed, and different results might be obtained in future cohorts recruited in the present times. Also, only clinical assessment was performed; cost effectiveness studies should follow, for a more complete overview of quality care for these patients.

      Conclusion

      The risk of late rupture of small incidental AAA diagnosed in octogenarian and nonagenarian patients is very small, especially when the AAA is < 40 mm in diameter. In contrast, global mortality is high. The discontinuation of surveillance in the smallest AAA seems safe. Patients with an AAA diameter closer to 55 mm are at a higher risk of rupture and reaching the surgical threshold. However, the majority will be deemed unfit for repair, with unclear benefit of surveillance. Careful early assessment of fitness, life expectancy, functionality, surgical risk, anatomical feasibility for EVAR and joint informed decision making would help select the patients who would benefit from follow up and eventual elective repair.

      Conflicts of interest

      None.

      Funding

      None.

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      Linked Article

      • Small Aneurysm Surveillance Over 80: Is it Worthwhile?
        European Journal of Vascular and Endovascular SurgeryVol. 62Issue 1
        • Preview
          Vega de Ceniga et al.1 conducted a retrospective cohort study of 310 patients with small abdominal aortic aneurysms (AAAs) aged over 80 years. The authors concluded that the risk of late rupture in octogenarian and nonagenarian patients is small and conservative management without follow up and repair seems reasonable for most of these patients. This was a large population that was contemporaneously followed up (follow up index 0.997).
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