Effectiveness and safety of structured exercise vs. no exercise for asymptomatic aortic aneurysm: systematic review and meta-analysis

Oliveira, Ricardo de Ávila; Nakajima, Eliza; Vasconcelos, Vladimir Tonello de; Riera, Rachel; Baptista-Silva, José Carlos Costa

doi:10.1590/1677-5449.190086

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Jornal Vascular Brasileiro

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REVIEW ARTICLE • J. Vasc. Bras. 19 • 2020 • https://doi.org/10.1590/1677-5449.190086 copy

Effectiveness and safety of structured exercise vs. no exercise for asymptomatic aortic aneurysm: systematic review and meta-analysis

Efetividade e segurança de exercícios estruturados versus sem exercício em pacientes assintomáticos com aneurisma de aorta: revisão sistemática e metanálise

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

We conducted a systematic review to compare the effectiveness and safety of exercise versus no exercise for patients with asymptomatic aortic aneurysm. We followed the guidelines set out in the Cochrane systematic review handbook. We searched Medline, Embase, CENTRAL, LILACS, PeDRO, CINAHL, clinicaltrials.gov, ICTRP, and OpenGrey using the MeSH terms “aortic aneurysm” and “exercise”. 1189 references were identified. Five clinical trials were included. No exercise-related deaths or aortic ruptures occurred in these trials. Exercise did not reduce the aneurysm expansion rate at 12 weeks to 12 months (mean difference [MD], −0.05; 95% confidence interval [CI], −0.13 to 0.03). Six weeks of preoperative exercise reduced severe renal and cardiac complications (risk ratio, 0.54; 95% CI, 0.31–0.93) and the length of intensive care unit stay (MD, −1.00; 95% CI, −1.26 to −0.74). Preoperative and postoperative forward walking reduced the length of hospital stay (MD, −0.69; 95% CI, −1.24 to −0.14). The evidence was graded as ‘very low’ level.

Keywords:
aortic aneurysm; abdominal aortic aneurysm; exercise; postoperative complications

Summary of findings:
Exercise compared to no exercise for aortic aneurysm patients at surveillance in intermediate term (7-12 w)
Patient or population: aortic aneurysm patients at surveillance in intermediate term (7-12 w)
Setting:
Intervention: exercise
Comparison: no exercise
Outcomes	Anticipated absolute effects ^{^} The risk in the exercise group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI); CI: Confidence interval; MD: Mean difference; RR: Risk ratio; GRADE Working Group grades of evidence. High certainty: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect. Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect. Explanations: (95% CI)		Relative effect (95% CI)	Nº of participants (studies)	Certainty of the evidence (GRADE)
Outcomes	Risk with no exercise	Risk with exercise	Relative effect (95% CI)	Nº of participants (studies)	Certainty of the evidence (GRADE)
Mortality follow up: range 7 weeks to 12 weeks	0 per 100	0 per 100 (0 to 0)	not estimable	263 (4 RCTs)	⨁◯◯◯ VERY LOW ^a,b,c,d
Aortic rupture follow up: range 7 weeks to 12 weeks	0 per 100	0 per 100 (0 to 0)	not estimable	263 (4 RCTs)	⨁◯◯◯ VERY LOW ^a,b,c,d
Aneurysm growth rate follow up: range 7 weeks to 12 weeks	The mean aneurysm growth rate was 0	The mean aneurysm growth rate in the exercise group was 0.06 lower (0.23 lower to 0.11 higher)	-	(2 RCTs)	⨁◯◯◯ VERY LOW ^b,c,d,e
Number of patients with at least one cardiovascular complication follow up: range 7 weeks to 12 weeks	0 per 100	0 per 100 (0 to 0)	RR 100.00 (0.07 to 35.46)	263 (4 RCTs)	⨁◯◯◯ VERY LOW ^a,b,c,d
Number of patients who reached threshold for surgery follow up: range 7 weeks to 12 weeks	0 per 100	0 per 100 (0 to 0)	not estimable	263 (4 RCTs)	⨁◯◯◯ VERY LOW ^a,b,c,d

Summary of findings:
Exercises compared to no exercise for aortic aneurysm patients at surveillance in long term (at 3 y)
Patient or population: aortic aneurysm patients at surveillance in long term (at 3 y)
Setting:
Intervention: exercise
Comparison: no exercise
Outcomes	Anticipated absolute effects ^* * The risk in the exercise group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval; MD: Mean difference; RR: Risk ratio. GRADE Working Group grades of evidence. High certainty: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect. Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect. Explanations: (95% CI)		Relative effect	Nº of participants	Certainty of the evidence (GRADE)
Outcomes	Risk with no exercise	Risk with exercise	(95% CI)	(studies)	Certainty of the evidence (GRADE)
Mortality follow up: mean 3 years	0 per 100	0 per 100 (0 to 0)	not estimable	140 (1 RCT)	⨁◯◯◯ VERY LOW a,b,c,d,e
Aortic rupture follow up: mean 3 years	0 per 100	0 per 100	not estimable	45	⨁◯◯◯
Aortic rupture follow up: mean 3 years	0 per 100	(0 to 0)	not estimable	(1 RCT)	VERY LOW ^a,b,d,e,f
Aneurysm growth rate	The mean aneurysm growth rate was 0.54	The mean aneurysm growth rate in the exercise group was 0.06 lower (0.23 lower to 0.11 higher)	-	45	⨁◯◯◯
follow up: mean 3 years	The mean aneurysm growth rate was 0.54		-	(1 RCT)	VERY LOW ^a,b,c,d,e
Number of patients with at least one cardiovascular complication	0 per 100	0 per 100	not estimable	45	⨁◯◯◯
follow up: mean 3 years	0 per 100	(0 to 0)	not estimable	(1 RCT)	VERY LOW ^a,b,c,d,e
Number of patients who reached threshold for surgery	13 per 100	4 per 100	RR 0.31	140	⨁◯◯◯
follow up: mean 3 years	13 per 100	(1 to 15)	(0.09 to 1.11)	(1 RCT)	VERY LOW ^a,b,c,d,e

Summary of findings:
Exercises compared to no exercise for aortic aneurysm patients before surgery
Patient or population: aortic aneurysm patients before surgery
Setting:
Intervention: exercise
Comparator: no exercise
Outcomes	Anticipated absolute effects ^* * The risk in the exercise group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval; RR: Risk ratio; GRADE Working Group grades of evidence. High certainty: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect. Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect. Explanations: (95% CI)		Relative effect (95% CI)	Nº of participants (studies)	Certainty of the evidence (GRADE)	Comment
Outcomes	Risk with no exercise	Risk with exercise	Relative effect (95% CI)	Nº of participants (studies)	Certainty of the evidence (GRADE)	Comment
Mortality follow up: mean 30 days	3 per 100	3 per 100	RR 1.00	124	⨁◯◯◯	Mortality was related to surgery. There was no mortality related to exercise.
Mortality follow up: mean 30 days	3 per 100	(3 to 3)	(0.93 to 1.07)	(1 RCT)	VERY LOW ^a,b
Aortic rupture follow up: mean 30 days	0 per 100	0 per 100	not estimable	124	⨁◯◯◯
Aortic rupture follow up: mean 30 days	0 per 100	(0 to 0)		(1 RCT)	VERY LOW ^a,b
Aneurysm growth rate - not measured	-	-	-	-	-
Number of patients with at least one cardiovascular complication follow up: mean 30 days	23 per 100	8 per 100	RR 0.36	124	⨁◯◯◯
	23 per 100	(3 to 21)	(0.14 to 0.93)	(1 RCT)	VERY LOW ^a,b
Number of patients who reached threshold for surgery - not measured	-	-	-	-	-

Summary of findings:
Exercise compared to no exercise for aortic aneurysm patients after surgery
Patient or population: aortic aneurysm patients after surgery
Setting:
Intervention: exercise
Comparison: no exercise
Outcomes	Anticipated absolute effects ^* * The risk in the exercise group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI); CI: Confidence interval. GRADE Working Group grades of evidence. High certainty: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect. Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect. (95% CI)		Relative effect	Nº of participants	Certainty of the evidence
Outcomes	Risk with no exercise	Risk with exercise	(95% CI)	(studies)	(GRADE)
Mortality - not measured	-	-	-	-	-
Aortic rupture - not measured	-	-	-	-	-
Aneurysm growth rate - not measured	-	-	-	-	-
Number of patients with at least one cardiovascular complication - not measured	-	-	-	-	-
Number of patients who reached threshold for surgery - not measured	-	-	-	-	-

Summary of findings:
Exercises compared to no exercise for aortic aneurysm patients before and after surgery
Patient or population: aortic aneurysm patients before and after surgery
Setting:
Intervention: exercise
Comparison: no exercise
Outcomes	Anticipated absolute effects ^* * The risk in the exercise group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). (95% CI)		Relative effect	Nº of participants	Certainty of the evidence	Comments
Outcomes	Risk with usual care	Risk with physical exercises	(95% CI)	(studies)	(GRADE)	Comments
Mortality - not measured	-	-	-	-	-
Aortic rupture - not measured	-	-	-	-	-
Aneurysm growth rate - not measured	-	-	-	-	-
Number of patients with at least one cardiovascular complication - not measured	-	-	-	-	-
Number of patients who reached threshold for surgery - not measured	-	-	-	-	-

Included studies:	Characteristics:
Kothmann et al. (2009)²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20...	Number of patients in exercise group: 20
	Number of patients in control group: 10
	Age (mean): exercise group: 69.5 years, control group: 69.4 years
	Time of intervention: At surveillance
	Sex: 20 men and 5 women
	Interventions: ^# # Text quoted from Kothmann et al.29; “Exercise sessions of 30 min exercise on static Life Fitness bicycle with a 5 min warm-up and cooling down period. Participants attended twice weekly in groups of 3 to 4 patients.
	Participants were required to exercise in zones 12 to 14 on the Borg scale.” ²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20...
	Outcomes: change in anaerobic threshold
	Follow-up: 7 weeks
Tew et al. (2012)¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...	Number of patients in exercise group: 14
	Number of patients in control group: 14
	Age: exercise group: 71 ± 8 years, control group: 74 ± 6 years.
	Time of intervention: at surveillance
	Sex: male/female: Exercise group: 10/1. Control group: 11/3
	Interventions: ^ Text quoted from Tew et al.18; “monitored physical exercises three times a week for 35 to 45 minutes at clinical unit; static Life Fitness bicycle in groups of 3 to 4 patients; treadmill walking; to expend up to 2000 Kcal.wk^-1.”
	Borg perceived exhaustion scale at zones of 12 to 14¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07... .
	Outcomes: **“anaerobic threshold; quality of life; safety; and blood markers (including C reactive protein, matrix metalloproteinase-9, and glycemia)”
	Follow-up: 12 weeks
Myers et al. (2014)¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...	Number of patients in exercise group: 72
	Number of patients in control group: 68
	Age: exercise group: 71.8 ± 7 years, control group: 71.3 ± 8 years.
	Time of intervention: at surveillance
	Sex: exercise group: 92% men, control group: 93% men.
	Interventions: ^†† †† Text quoted from Myers et al.11; “monitored physical exercises three times a week workout for 45 minutes at clinical unit or home or both locations; including static Life Fitness bicycle in groups of 3 to 4 patients; treadmill walking; stair climbing; elliptical training; rowing; to expend up to 2000 Kcal.wk^-1.”
	Borg perceived exhaustion scale at zones of 12 to 14¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182... .
	Outcomes: safety; aneurysm growth rates.
	Follow-up: up to 36 months
Barakat et al. (2016)²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000...	Number of patients in exercise group: 62
	Number of patients in control group: 62
	Age: exercise group: 73.8 years, control group: 72.9 years.
	Time of intervention: during preoperative period.
	Sex: exercise group: 6 women; control group: 7 women.
	Interventions: ^‡‡ ‡‡ Text quoted from Barakat et al.28. “5-minute warm up and stretching, cycle ergometer against moderate resistance for 2 minutes, heel-raise repetitions for 2 minutes, knee extensions against resistance repetitions for 2 minutes, dumbbells’ biceps/arm curls repetitions for 2 minutes, step-up lunges repetitions for 2 minutes, knee bends (bodyweight) repetitions for 2 minutes, and 5 minutes for cool down and stretching. Between each of the exercise stations, patients either walked around the gym or on a treadmill or rested for 2 minutes before moving on to the next exercise.”
	Outcomes: composite postoperative cardiac, renal and postoperative respiratory complications; length of hospital stay, and ITU stay, “APACHE II scores recorded at HDU/ITU admission, the occurrence of systemic inflammatory response syndrome (SIRS), 30-day mortality, postoperative bleeding requiring reoperation or transfusion of more than 4 units of blood products within 72 hours, and the need for reoperation.”
	Follow-up: 12 weeks
Wnuk et al. (2016)³⁰30 Wnuk BR, Durmała J, Ziaja K, Kotyla P, Woźniewski M, Błaszczak E. A controlled trial of the efficacy of a training walking program in patients recovering from abdominal aortic aneurysm surgery. Adv Clin Exp Med. 2016;25(6):1241-371. http://dx.doi.org/10.17219/acem/62239. PMid:28028979. http://dx.doi.org/10.17219/acem/62239...	Number of patients in exercise group: 44 (22 backward walking; 22 forward walking)
	Number of patients in control group: 21
	Age: exercise group: 71 ± 8 years, control group: 74 ± 6 years.
	Time of intervention: during postoperative period.
	Sex ratio: male/female: Exercise group: 10/1. Control group: 11/3.
	Interventions: postoperative backward walking training, and postoperative forward walking training.
	Outcomes: six minutes walking test; heart rate training; standard metabolic equivalent; FVC, FEV1, FEV1/FVC, PEF, hospital-stay.
	Follow-up: 7 days
Excluded studies:	Reasons for exclusion:
Dronkers et al. (2008)³¹31 Dronkers J, Veldman A, Hoberg E, van der Waal C, van Meeteren N. Prevention of pulmonary complications after upper abdominal surgery by preoperative intensive inspiratory muscle training: a randomized controlled pilot study. Clin Rehabil. 2008;22(2):134-42. http://dx.doi.org/10.1177/0269215507081574. PMid:18057088. http://dx.doi.org/10.1177/02692155070815...	RCT comparing respiratory physical therapy with usual care in patients with an aortic aneurysm scheduled for surgery. Physical therapy was not considered to be exercise.
Nakayama et al. (2018)³²32 Nakayama A, Morita H, Nagayama M, et al. Cardiac rehabilitation protects against the expansion of abdominal aortic aneurysm. J Am Heart Assoc. 2018;7(5):e007959. http://dx.doi.org/10.1161/JAHA.117.007959. PMid:29487112. http://dx.doi.org/10.1161/JAHA.117.00795...	Retrospective cohort comparing cardiac rehabilitation with usual care with a follow up of 3000 days. Not a clinical trial.
	Main ID: JPRN-UMIN000028237
Hayashi et al. (2016)³³33 Hayashi K, Hirashiki A, Kodama A, et al. Impact of preoperative regular physical activity on postoperative course after open abdominal aortic aneurysm surgery. Heart Vessels. 2016;31(4):578-83. http://dx.doi.org/10.1007/s00380-015-0644-6. PMid:25666952. http://dx.doi.org/10.1007/s00380-015-064...	Case-control study. Patients were allocated to fit or unfit groups according to physical capacity.
Bailey et al. (2018)³⁴34 Bailey TG, Perissiou M, Windsor MT, et al. Effects of acute exercise on endothelial function in patients with abdominal aortic aneurysm. Am J Physiol Heart Circ Physiol. 2018;314(1):H19-30. http://dx.doi.org/10.1152/ajpheart.00344.2017. PMid:28939648. http://dx.doi.org/10.1152/ajpheart.00344...	RCT evaluating effect of acute exercise on endothelial function in patients with abdominal aortic aneurysm. The study describes acute flow-mediated-dilatation and not the outcomes of the exercise over a long period as a necessity of treatment for the disease, so it was considered physical activity and not physical exercises.
Weston et al. (2017)³⁵35 Weston M, Batterham AM, Tew GA, et al. Patients awaiting surgical repair for large abdominal aortic aneurysms can exercise at moderate to hard intensities with a low risk of adverse events. Front Physiol. 2016;7:684. PMid:28119627.	RCT assessing the accuracy of high-intensity interval training (HIT) in patients awaiting repair of large abdominal aortic aneurysms.
Ongoing studies:	Characteristics:
ClinicalTrials.gov (2017)³⁶36 ClinicalTrials.gov. Surviving aneurysm surgery: a pilot study on exercise training in abdominal aortic aneurysm patients. USA: U. S. National Library of Medicine; 2017. NCT01805973.	As contacted by e-mail: NCT01805973 (14) has been changed to “The AAA Get fit trial”:
	Randomized, parallel, blinded to assessors study: ^* * Text quoted from ClinicalTrials.gov36; “…to explore the effectiveness of a 20-week community (either home or gym-based) exercise programme to achieve sustained improvements in peak VO2 and AT, as measured by CPET, in AAA patients. Changes in QoL, habitual activity levels and cardiovascular risk will also be assessed.”
	ClinicalTrials.gov Identifier: NCT02997618
ClinicalTrials.gov (2017)³⁷37 ClinicalTrials.gov. The assessment of the feasibility of a home based exercise programme in the older patient following major surgery. USA: U. S. National Library of Medicine; 2017. NCT03064308.	Randomized, parallel, open study: ^† † Text quoted from ClinicalTrials.gov37; “…to establish if it is possible for patients who have undergone major body surgery to complete a home based exercise training program and complete the assessments required to measure physical and cognitive function … [and] ... whether it is possible to improve the physical function of older patients undergoing major abdominal surgery in the period following surgery by using a simple exercise regimen that can be carried out at home..”
	ClinicalTrials.gov Identifier: NCT03064308
ClinicalTrials.gov (2017)³⁸38 ClinicalTrials.gov. Prehabilitation for aortic repair patients - full text view. USA: U. S. National Library of Medicine; 2017. NCT02767518.	Randomized, parallel, blinded to assessors study: ^‡ ‡ Text quoted from ClinicalTrials.gov38; “…comparing the effect of a “prehabilitation” program to usual care on quality of life and clinical outcomes in patients undergoing elective repair of their thoracic aorta.”
	ClinicalTrials.gov Identifier: NCT02767518
Mosk 2017³⁹39 Mosk A. Pre operative optimisation pathway for elderly surgical patients - OUTO. The Netherlands: Netherlands Trial Register. NTR5932.	Non-randomized, two or more arms study:
	\|\| “to evaluate if Multicomponent prehabilitation will reduce postoperative adverse events, primary delirium, which will result in less long-term adverse consequences.”
	Main ID: NTR5932

A) Clinical trials:
Study/bias	Support for judgment
Barakat et al. ²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000...	Quote: “Randomization was performed using opaque, sealed, identical envelopes containing the treatment allocation, according to a computer-generated sequence prepared by an independent professional. Patients were randomized into one of the 2 groups—the exercise (intervention) group or the standard treatment (control) group. The randomization process was witnessed by an independent research professional and was carried out during the initial visit after obtaining informed consent, but before preoperative assessments and interventions.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
Random sequence generation (selection bias)
“Low risk”	Comment: randomization was described and seems to be appropriate.
Allocation concealment (selection bias) “Unclear risk”	Comment: not described
Blinding of participants and personnel (performance bias) – all-cause mortality	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“High risk”	Comment: due to the nature of the intervention, it is impossible to blind patients.
Blinding of participants and personnel (performance bias) – number of patients with aortic rupture.	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“High risk”	Comment: due to the nature of the intervention it is impossible to blind patients.
Blinding of participants and personnel (performance bias) – aneurysm growth	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“High risk”	Comment: due to the nature of the intervention it is impossible to blind patients.
Blinding of participants and personnel (performance bias) – quality of life	Not assessed
Blinding of participants and personnel (performance bias) – number of patients referred for surgery	Not assessed
Blinding of participants and personnel (performance bias) – peri-operative complications	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“High risk”	Comment: due to the nature of the intervention it is impossible to blind patients.
Há Blinding of participants and personnel (performance bias) – postoperative complications	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“High risk”	Comment: due to the nature of the intervention it is impossible to blind patients.
Blinding of participants and personnel (performance bias) – cardiovascular mortality	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“High risk”	Comment: due to the nature of the intervention it is impossible to blind patients.
Blinding of participants and personnel (performance bias) – hospital stay	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“High risk”	Comment: due to the nature of the intervention it is impossible to blind patients.
Blinding of participants and personnel (performance bias) – VEF1	Not assessed
Blinding of outcome assessment (detection bias) – all-cause mortality	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“Low risk”	Comment: blinding of outcome assessment was described and seems to be appropriate
Blinding of outcome assessment (detection bias) – number of patients with aortic rupture	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“Low risk”	Comment: blinding of outcome assessment was described and seems to be appropriate
Blinding of outcome assessment (detection bias) – aneurysm growth	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“Low risk”	Comment: blinding of outcome assessment was described and seems to be appropriate
Blinding of outcome assessment (detection bias) – quality of life	Not assessed
Blinding of outcome assessment (detection bias) – number of patients referred for surgery	Not applicable
Blinding of outcome assessment (detection bias) – peri-operative complications	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“Low risk”	Comment: blinding of outcome assessment was described and seems to be appropriate
Blinding of outcome assessment (detection bias) – postoperative complications	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“Low risk”	Comment: blinding of outcome assessment was described and seems to be appropriate
Blinding of outcome assessment (detection bias) – cardiovascular mortality	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“Low risk”	Comment: blinding of outcome assessment was described and seems to be appropriate
Blinding of outcome assessment (detection bias) – hospital stay	Quote: “Clinicians including consultant surgeons, anesthetists, department’s medical and nursing staff, and interventional radiologists were blinded to patient group allocation. This was ensured by explaining the importance of blinding to all study participants and performing all study procedures in the separate Academic department.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000... (p. 48).
“Low risk”	Comment: blinding of outcome assessment was described and seems to be appropriate
Blinding of outcome assessment (detection bias) – VEF1	Not assessed
Incomplete outcome data (attrition bias) – all-cause mortality	Quote: “Twelve patients—6 from each group—withdrew from the study before operative interventions as their procedures were cancelled or postponed. No patients were lost to follow-up. Sixty-two patients from each group were included in the final analysis.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000...
“Low risk”	Comment: there were 8.8% losses from each group and they were explained. There were no other loses of follow up.
Incomplete outcome data (attrition bias) – number of patients with aortic rupture	Quote: “Twelve patients—6 from each group—withdrew from the study before operative interventions as their procedures were cancelled or postponed. No patients were lost to follow-up. Sixty-two patients from each group were included in the final analysis.”²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000...
“Low risk”	Comment: there were 8.8% losses from each group and they were explained There were no other loses of follow up.
Incomplete outcome data (attrition bias) – aneurysm growth	Quote: “Twelve patients—6 from each group—withdrew from the study before operative interventions as their procedures were cancelled or postponed. No patients were lost to follow-up. Sixty-two patients from each group were included in the final analysis.” ²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000...
“Low risk”	Comment: there were 8.8% losses from each group and they were explained There were no other loses of follow up.
Incomplete outcome data (attrition bias) – quality of life	Not assessed
Incomplete outcome data (attrition bias) – number of patients referred for surgery	Not applicable
Incomplete outcome data (attrition bias) – peri-operative complications	Quote: “Twelve patients—6 from each group—withdrew from the study before operative interventions as their procedures were cancelled or postponed. No patients were lost to follow-up. Sixty-two patients from each group were included in the final analysis.” ²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000...
“Low risk”	Comment: there were 8.8% losses from each group and they were explained There were no other loses of follow up.
Incomplete outcome data (attrition bias) – postoperative complications	Quote: “Twelve patients—6 from each group—withdrew from the study before operative interventions as their procedures were cancelled or postponed. No patients were lost to follow-up. Sixty-two patients from each group were included in the final analysis.” ²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000...
“Low risk”	Comment: there were 8.8% losses from each group and they were explained There were no other loses of follow up.
Incomplete outcome data (attrition bias) – cardiovascular mortality	Quote: “Twelve patients—6 from each group—withdrew from the study before operative interventions as their procedures were cancelled or postponed. No patients were lost to follow-up. Sixty-two patients from each group were included in the final analysis.” ²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000...
“Low risk”	Comment: there were 8.8% losses from each group and they were explained There were no other loses of follow up.
Incomplete outcome data (attrition bias) – hospital stay	Quote: “Twelve patients—6 from each group—withdrew from the study before operative interventions as their procedures were cancelled or postponed. No patients were lost to follow-up. Sixty-two patients from each group were included in the final analysis.” ²⁸28 Barakat HM, Shahin Y, Khan JA, McCollum PT, Chetter IC. Preoperative supervised exercise improves outcomes after elective abdominal aortic aneurysm repair. Ann Surg. 2016;264(1):47-53. http://dx.doi.org/10.1097/SLA.0000000000001609. PMid:26756766. http://dx.doi.org/10.1097/SLA.0000000000...
“Low risk”	Comment: there were 8.8% losses from each group and they were explained There were no other loses of follow up.
Incomplete outcome data (attrition bias) – VEF1	Not assessed
Selective reporting (reporting bias)	Comment: A protocol has been published: NCT01062594. All proposed outcomes were reported.
“Low risk”	Comment: there were no imbalances between groups. There were two different interventions (endovascular and open surgery). The numbers were balanced between groups.
Other bias
“Low risk”
Kothmann et al.²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20...
Random sequence generation (selection bias)	Quote: “...participants were randomly allocated (via sealed envelopes) to a supervised exercise intervention or to the control group (usual care).”²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20...
“Low risk”	Comment: Randomization was described and seems to be appropriate.
Allocation concealment (selection bias)	Comment: not described
“Unclear risk”	Comment: not described
Blinding of participants and personnel (performance bias) – all-cause mortality	Comment: no information provided. Probably not done due to the nature of the intervention.
“High risk”
Blinding of participants and personnel (performance bias) – number of patients with aortic rupture.	Comment: no information provided. Probably not done due to the nature of the intervention.
“High risk”
Blinding of participants and personnel (performance bias) – aneurysm growth	Not assessed
Blinding of participants and personnel (performance bias) – quality of life	Not assessed
Blinding of participants and personnel (performance bias) – number of patients referred for surgery	Comment: no information provided. Probably not done due to the nature of the intervention.
“High risk”
Blinding of participants and personnel (performance bias) – peri-operative complications	Not applicable
Blinding of participants and personnel (performance bias) – postoperative complications	Not applicable
Blinding of participants and personnel (performance bias) – cardiovascular mortality	Comment: no information provided. Probably not done due to the nature of the intervention.
“High risk”
Blinding of participants and personnel (performance bias) – hospital stay	Not applicable
Blinding of participants and personnel (performance bias) – VEF1	Not assessed
Blinding of outcome assessment (detection bias) – all-cause mortality	Quote: “In the paper we state: “The investigator reading AT results (G.D.) was blinded to group allocation.” Simply, GD was provided with the output from the cardiopulmonary exercise tests and derived the anaerobic threshold for each participant without knowledge of group assignment, i.e., blind.”²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20... Provided by email
“Low risk”	Comment: blinding of outcome assessment properly described.
Blinding of outcome assessment (detection bias) – number of patients with aortic rupture	Quote: “In the paper we state: “The investigator reading AT results (G.D.) was blinded to group allocation.” Simply, GD was provided with the output from the cardiopulmonary exercise tests and derived the anaerobic threshold for each participant without knowledge of group assignment, i.e., blind.”²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20... Provided by email
“Low risk”	Comment: blinding of outcome assessment properly described.
Blinding of outcome assessment (detection bias) – aneurysm growth	Not assessed
Blinding of outcome assessment (detection bias) – quality of life	Not assessed
Blinding of outcome assessment (detection bias) – number of patients referred for surgery	Quote: “In the paper we state: “The investigator reading AT results (G.D.) was blinded to group allocation.” Simply, GD was provided with the output from the cardiopulmonary exercise tests and derived the anaerobic threshold for each participant without knowledge of group assignment, i.e., blind.”²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20... Provided by email
“Low risk”	Comment: blinding of outcome assessment properly described.
Blinding of outcome assessment (detection bias) – peri-operative complications	Not applicable
Blinding of outcome assessment (detection bias) – postoperative complications	Not applicable
Blinding of outcome assessment (detection bias) – cardiovascular mortality	Quote: “In the paper we state: “The investigator reading AT results (G.D.) was blinded to group allocation.” Simply, GD was provided with the output from the cardiopulmonary exercise tests and derived the anaerobic threshold for each participant without knowledge of group assignment, i.e., blind.”²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20... Provided by email
“Low risk”	Comment: blinding of outcome assessment properly described.
Blinding of outcome assessment (detection bias) – hospital stay	Not applicable
Blinding of outcome assessment (detection bias) – VEF1	Not assessed
Incomplete outcome data (attrition bias) – all-cause mortality	“Of these, 17 of 20 and eight of 10 completed the study period in the exercise and control groups, respectively, producing full data sets for analysis”²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20...
“Unclear risk”	Comment: (There was 15% losses from the intervention group and 20% from the control group. We are not sure about the extent to which this could affect the results).
Incomplete outcome data (attrition bias) – number of patients with aortic rupture	“Of these, 17 of 20 and eight of 10 completed the study period in the exercise and control groups, respectively, producing full data sets for analysis”²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20...
“Unclear risk”	Comment: (There was 15% losses from the intervention group and 20% from the control group. We are not sure about the extent to which this could affect the results).
Incomplete outcome data (attrition bias) – aneurysm growth	Not assessed
Incomplete outcome data (attrition bias) – quality of life	Not assessed
Incomplete outcome data (attrition bias) – number of patients referred for surgery	“Of these, 17 of 20 and eight of 10 completed the study period in the exercise and control groups, respectively, producing full data sets for analysis”²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20...
“unclear risk”	Comment: There was 15% losses from the intervention group and 20% from the control group. We are not sure to what extent this could affect the results.
Incomplete outcome data (attrition bias) – peri-operative complications	Not applicable
Incomplete outcome data (attrition bias) – postoperative complications	Not applicable
Incomplete outcome data (attrition bias) – cardiovascular mortality	“Of these, 17 of 20 and eight of 10 completed the study period in the exercise and control groups, respectively, producing full data sets for analysis”²⁹29 Kothmann E, Danjoux G, Owen SJ, Parry A, Turley AJ, Batterham AM. Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms. Anaesthesia. 2009;64(1):9-13. http://dx.doi.org/10.1111/j.1365-2044.2008.05690.x. PMid:19086999. http://dx.doi.org/10.1111/j.1365-2044.20...
“Unclear risk”	Comment: There was 15% losses from the intervention group and 20% from the control group. We are not sure to what extent this could affect the results.
Incomplete outcome data (attrition bias) – hospital stay	Not applicable
Incomplete outcome data (attrition bias) – VEF1	Not assessed
Selective reporting (reporting bias)	Comment: All the proposed outcomes were reported.
“Low risk”	Comment: All the proposed outcomes were reported.
Other bias	Comment: There is an uncertainty about the balance between groups at baseline, since no p value was provided. We are not sure to what extent this could affect the results.
“Unclear risk”
Myers et al.¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
Random sequence generation (selection bias)	Quote: “One hundred and forty patients with small AAAs (72 T 8 yr) were randomised to exercise training (n = 72) or usual care (n = 68)”¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“Unclear risk”	Comment: Not described.
Allocation concealment (selection bias)	Comment: not described
“Unclear risk”	Comment: not described
Blinding of participants and personnel (performance bias) – all-cause mortality	Comment: not stated. Probably not done since the nature of intervention precluded this masking
“High risk”
Blinding of participants and personnel (performance bias) – number of patients with aortic rupture.	Comment: not stated. Probably not done since the nature of intervention precluded this masking
“High risk”
Blinding of participants and personnel (performance bias) – aneurysm growth	Comment: not stated. Probably not done since the nature of intervention precluded this masking
“High risk”
Blinding of participants and personnel (performance bias) – quality of life	Not assessed
Blinding of participants and personnel (performance bias) – number of patients referred for surgery	Comment: not stated. Probably not done since the nature of intervention precluded this masking
“High risk”
Blinding of participants and personnel (performance bias) – peri-operative complications	Not assessed
Blinding of participants and personnel (performance bias) – postoperative complications	Not assessed
Blinding of participants and personnel (performance bias) – cardiovascular mortality	Comment: not stated. Probably not done since the nature of intervention precluded this masking
“High risk”
Blinding of participants and personnel (performance bias) – hospital stay	Not assessed
Blinding of participants and personnel (performance bias) – VEF1	Not assessed
Blinding of outcome assessment (detection bias) – all-cause mortality	Quote: “Both the RVT and the individual making the diameter measurements were blinded to group randomisation”. Answered by e-mail: “both were unaware of the intervention or control group.”¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“Unclear risk”	Comment: no information provided for data assessors
Blinding of outcome assessment (detection bias) – number of patients with aortic rupture	Quote: Quote: “Both the RVT and the individual making the diameter measurements were blinded to group randomisation”. Answered by e-mail: “both were unaware of the intervention or control group.”¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“Unclear risk”	Comment: no information provided for data assessors
Blinding of outcome assessment (detection bias) – aneurysm growth	Quote: “Both the RVT and the individual making the diameter measurements were blinded to group randomisation”. Answered by e-mail: “both were unaware of the intervention or control group.”¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“Unclear risk”	Comment: no information provided for data assessors
Blinding of outcome assessment (detection bias) – quality of life	Not assessed
Blinding of outcome assessment (detection bias) – number of patients referred for surgery	Quote: “Both the RVT and the individual making the diameter measurements were blinded to group randomisation”. Answered by e-mail: “both were unaware of the intervention or control group.”¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“Unclear risk”	Comment: no information provided for data assessors
Blinding of outcome assessment (detection bias) – peri-operative complications	Not assessed
Blinding of outcome assessment (detection bias) – postoperative complications	Not assessed
Blinding of outcome assessment (detection bias) – cardiovascular mortality	Quote: “Both the RVT and the individual making the diameter measurements were blinded to group randomisation”. Answered by e-mail: “both were unaware of the intervention or control group.”¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“Unclear risk”	Comment: no information provided for data assessors
Blinding of outcome assessment (detection bias) – hospital stay	Not assessed
Blinding of outcome assessment (detection bias) – VEF1	Not assessed
Incomplete outcome data (attrition bias) – all-cause mortality	Quote: “81% of subjects completed at least 1 year in the trial”¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“High risk”	Comment: There were 19% losses in one year. Additionally, at the end of follow-up, there were 39 losses from the intervention group and 36 from the control group. The reasons for these losses are unclear.
Incomplete outcome data (attrition bias) – number of patients with aortic rupture	Quote: “81% of subjects completed at least 1 year in the trial”¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“High risk”	Comment: There were 19% losses in one year. Additionally, at the end of follow-up, there were 39 losses from the intervention group and 36 from the control group. The reasons for these losses are unclear.
Incomplete outcome data (attrition bias) – aneurysm growth	Quote: “81% of subjects completed at least 1 year in the trial”¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“High risk”	Comment: There were 19% losses in one year. Additionally, at the end of follow-up, there were 39 losses from the intervention group and 36 from the control group. The reasons for these losses are unclear.
Incomplete outcome data (attrition bias) – quality of life	Not assessed
Incomplete outcome data (attrition bias) – number of patients referred for surgery	Quote: “81% of subjects completed at least 1 year in the trial”¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“High risk”	Comment: There were 19% losses in one year. Additionally, at the end of follow-up, there were 39 losses from the intervention group and 36 from the control group. The reasons for these losses are unclear.
Incomplete outcome data (attrition bias) – peri-operative complications	Not assessed
Incomplete outcome data (attrition bias) – postoperative complications	Not assessed
Incomplete outcome data (attrition bias) – cardiovascular mortality	Quote: “81% of subjects completed at least 1 year in the trial”¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“High risk”	Comment: There were 19% losses in one year. Additionally, at the end of follow-up, there were 39 losses from the intervention group and 36 from the control group. The reasons for these losses are unclear.
Incomplete outcome data (attrition bias) – hospital stay	Not assessed
Incomplete outcome data (attrition bias) – VEF1	Not assessed
Selective reporting (reporting bias)	Quote: Protocol available at Clinicaltrials.gov, identifier: NCT00349947.
“Low risk”	Comment: protocol described. All proposed outcomes were reported
Other bias	Comment: There was an “imbalance between groups at baseline regarding BMI mean at baseline (p =0.002) and frequency of diabetes (30% vs. 12% in the exercise and usual care groups, respectively, P = 0.01).” ¹¹11 Myers J, Mcelrath M, Jaffe A, et al. A randomized trial of exercise training in abdominal aortic aneurysm disease. Med Sci Sports Exerc. 2014;46(1):2-9. http://dx.doi.org/10.1249/MSS.0b013e3182a088b8. PMid:23793234. http://dx.doi.org/10.1249/MSS.0b013e3182...
“Unclear risk”	We are not sure to what extent this could affect the results.
Tew et al.¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
Random sequence generation (selection bias)	Quote: “Allocation to exercise or control was done using a randomization sequence created by an independent researcher before study commencement.”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“Unclear risk”	Comment: unclear information
Allocation concealment (selection bias)	Quote: “The study researchers were made aware of this sequence on a case-by-case basis after baseline assessments were completed.”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“Unclear risk”	Comment: unclear information
Blinding of participants and personnel (performance bias) – all-cause mortality	Quote: “Ventilatory threshold was determined by an independent exercise physiologist blinded to group allocation using the v-slope and ventilatory equivalents methods.”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“High risk”	Comment: The nature of the intervention precluded this masking
Blinding of participants and personnel (performance bias) – number of patients with aortic rupture.	Quote: “Ventilatory threshold was determined by an independent exercise physiologist blinded to group allocation using the v-slope and ventilatory equivalents methods.”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“High risk”	Comment: The nature of the intervention precluded this masking
Blinding of participants and personnel (performance bias) – aneurysm growth	Quote: “Ventilatory threshold was determined by an independent exercise physiologist blinded to group allocation using the v-slope and ventilatory equivalents methods.”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“High risk”	Comment: The nature of the intervention precluded this masking
Blinding of participants and personnel (performance bias) – quality of life	Quote: “Ventilatory threshold was determined by an independent exercise physiologist blinded to group allocation using the v-slope and ventilatory equivalents methods.”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“High risk”	Comment: The nature of the intervention precluded this masking
Blinding of participants and personnel (performance bias) – number of patients referred for surgery	Not assessed
Blinding of participants and personnel (performance bias) – peri-operative complications	Not applicable
Blinding of participants and personnel (performance bias) – postoperative complications	Not applicable
Blinding of participants and personnel (performance bias) – cardiovascular mortality	Quote: “Ventilatory threshold was determined by an independent exercise physiologist blinded to group allocation using the v-slope and ventilatory equivalents methods.”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“High risk”	Comment: The nature of the intervention precluded this masking
Blinding of participants and personnel (performance bias) – hospital stay	Not applicable
Blinding of participants and personnel (performance bias) – VEF1	Not assessed
Blinding of outcome assessment (detection bias) – all-cause mortality	Quote: “The study researchers were made aware of this sequence on a case-by-case basis after baseline assessments were completed”.¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“High risk”	Comment: There was no blinding
Blinding of outcome assessment (detection bias) – number of patients with aortic rupture	Quote: “The study researchers were made aware of this sequence on a case-by-case basis after baseline assessments were completed”.¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“High risk”	Comment: There was no blinding
Blinding of outcome assessment (detection bias) – aneurysm growth	Quote: “The study researchers were made aware of this sequence on a case-by-case basis after baseline assessments were completed”.¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“High risk”	Comment: There was no blinding
Blinding of outcome assessment (detection bias) – quality of life	Quote: The study researchers were made aware of this sequence on a case-by-case basis after baseline assessments were completed”.¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“High risk”	Comment: There was no blinding
Blinding of outcome assessment (detection bias) – number of patients referred for surgery	Not assessed
Blinding of outcome assessment (detection bias) – peri-operative complications	Not applicable
Blinding of outcome assessment (detection bias) – postoperative complications	Not applicable
Blinding of outcome assessment (detection bias) – cardiovascular mortality	Quote: The study researchers were made aware of this sequence on a case-by-case basis after baseline assessments were completed”.¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“High risk”	Comment: There was no blinding
Blinding of outcome assessment (detection bias) – hospital stay	Not applicable
Blinding of outcome assessment (detection bias) – VEF1	Not assessed
Incomplete outcome data (attrition bias) – all-cause mortality	Quote: “Three participants did not complete the exercise intervention: 1 withdrew because of being diagnosed with cancer, 1 underwent pacemaker implantation, and 1 suffered a back injury at home”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“Unclear risk”	Comment: There were about 20% of losses from the intervention group, with reasons provided. We are not sure to what extent this could affect the results.
Incomplete outcome data (attrition bias) – number of patients with aortic rupture	Quote: “Three participants did not complete the exercise intervention: 1 withdrew because of being diagnosed with cancer, 1 underwent pacemaker implantation, and 1 suffered a back injury at home”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“Unclear risk”	Comment: There were about 20% of losses from the intervention group, with reasons provided. We are not sure to what extent this could affect the results.
Incomplete outcome data (attrition bias) – aneurysm growth	Quote: “Three participants did not complete the exercise intervention: 1 withdrew because of being diagnosed with cancer, 1 underwent pacemaker implantation, and 1 suffered a back injury at home”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“Unclear risk”	Comment: There were about 20% of losses from the intervention group, with reasons provided. We are not sure to what extent this could affect the results.
Incomplete outcome data (attrition bias) – quality of life	Quote: “Three participants did not complete the exercise intervention: 1 withdrew because of being diagnosed with cancer, 1 underwent pacemaker implantation, and 1 suffered a back injury at home”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“Unclear risk”	Comment: There were about 20% of losses from the intervention group, with reasons provided. We are not sure to what extent this could affect the results.
Incomplete outcome data (attrition bias) – number of patients referred for surgery	Not assessed
Incomplete outcome data (attrition bias) – peri-operative complications	Not applicable
Incomplete outcome data (attrition bias) – postoperative complications	Not applicable
Incomplete outcome data (attrition bias) – cardiovascular mortality	Quote: “Three participants did not complete the exercise intervention: 1 withdrew because of being diagnosed with cancer, 1 underwent pacemaker implantation, and 1 suffered a back injury at home”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“Unclear risk”	Comment: There were about 20% of losses from the intervention group, with reasons provided. We are not sure to what extent this could affect the results.
Incomplete outcome data (attrition bias) – hospital stay	Not applicable
Incomplete outcome data (attrition bias) – VEF1	Not assessed
Selective reporting (reporting bias)	Quote: “The study was registered in ClinicalTrials.gov under reference no. NCT01234610.”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
“Low risk”	Comment: there is a protocol and it seems to be appropriate. All proposed outcomes were reported.
“Low risk”	Does not show the data for the quality of life outcome: “...or any of the 8 quality of life domains (P.05; data not presented)”¹⁸18 Tew GA, Moss J, Crank H, Mitchell PA, Nawaz S. Endurance exercise training in patients with small abdominal aortic aneurysm: a randomized controlled pilot study. Arch Phys Med Rehabil. 2012;93(12):2148-53. http://dx.doi.org/10.1016/j.apmr.2012.07.012. PMid:22846453. http://dx.doi.org/10.1016/j.apmr.2012.07...
Other bias	Comment: There is an uncertainty about the balance between groups at baseline, since no p value was provided. We are not sure to what extent this could affect the results.
“Unclear risk
Wnuk et al.³⁰30 Wnuk BR, Durmała J, Ziaja K, Kotyla P, Woźniewski M, Błaszczak E. A controlled trial of the efficacy of a training walking program in patients recovering from abdominal aortic aneurysm surgery. Adv Clin Exp Med. 2016;25(6):1241-371. http://dx.doi.org/10.17219/acem/62239. PMid:28028979. http://dx.doi.org/10.17219/acem/62239...
Random sequence generation (selection bias)	Quote: “The randomization of the study was conducted by drawing envelopes containing a number of the appropriate group – single blind study. Patients with the number 1 were qualified for the experimental group with backward walking training (group I), with number 2 for the experimental group with forward walking training (group II) and 3 for the control group.”³⁰30 Wnuk BR, Durmała J, Ziaja K, Kotyla P, Woźniewski M, Błaszczak E. A controlled trial of the efficacy of a training walking program in patients recovering from abdominal aortic aneurysm surgery. Adv Clin Exp Med. 2016;25(6):1241-371. http://dx.doi.org/10.17219/acem/62239. PMid:28028979. http://dx.doi.org/10.17219/acem/62239...
“Low risk”	Comment: randomization considered done and apparently appropriate.
Allocation concealment (selection bias)	Comment: not stated
“Unclear risk”	Comment: not stated
Blinding of participants and personnel (performance bias) – all-cause mortality	Not assessed
Blinding of participants and personnel (performance bias) – number of patients with aortic rupture.	Not applicable
Blinding of participants and personnel (performance bias) – aneurysm growth	Not applicable
Blinding of participants and personnel (performance bias) – quality of life	Not assessed
Blinding of participants and personnel (performance bias) – number of patients referred for surgery	Not applicable
Blinding of participants and personnel (performance bias) – peri-operative complications	Not applicable
Blinding of participants and personnel (performance bias) – postoperative complications	Not assessed
Blinding of participants and personnel (performance bias) – cardiovascular mortality	Not assessed
Blinding of participants and personnel (performance bias) – hospital stay	Quote: “single blind study”³⁰30 Wnuk BR, Durmała J, Ziaja K, Kotyla P, Woźniewski M, Błaszczak E. A controlled trial of the efficacy of a training walking program in patients recovering from abdominal aortic aneurysm surgery. Adv Clin Exp Med. 2016;25(6):1241-371. http://dx.doi.org/10.17219/acem/62239. PMid:28028979. http://dx.doi.org/10.17219/acem/62239...
“High risk”	Comment: not blinded
Blinding of participants and personnel	Quote: “single blind study”³⁰30 Wnuk BR, Durmała J, Ziaja K, Kotyla P, Woźniewski M, Błaszczak E. A controlled trial of the efficacy of a training walking program in patients recovering from abdominal aortic aneurysm surgery. Adv Clin Exp Med. 2016;25(6):1241-371. http://dx.doi.org/10.17219/acem/62239. PMid:28028979. http://dx.doi.org/10.17219/acem/62239...
(performance bias) – VEF1	Comment: not blinded
“High risk”	Comment: not blinded
Blinding of outcome assessment (detection bias) – all-cause mortality	Not assessed
Blinding of outcome assessment (detection bias) – number of patients with aortic rupture	Not applicable
Blinding of outcome assessment (detection bias) – aneurysm growth	Not applicable
Blinding of outcome assessment (detection bias) – quality of life	Not assessed
Blinding of outcome assessment (detection bias) – number of patients referred for surgery	Not applicable
Blinding of outcome assessment (detection bias) – peri-operative complications	Not applicable
Blinding of outcome assessment (detection bias) – postoperative complications	Not assessed
Blinding of outcome assessment (detection bias) – cardiovascular mortality	Not assessed
Blinding of outcome assessment (detection bias) – hospital stay	Quote: described as a single blinded study. Replied by e-mail 09/27/2017: “Measurement of gait parameters and spirometry was evaluated by physiotherapist from the Department of Rehabilitation. Routine physiotherapy and training walking in three groups was conducted by physiotherapist from the department of General and Vascular Surgery.”³⁰30 Wnuk BR, Durmała J, Ziaja K, Kotyla P, Woźniewski M, Błaszczak E. A controlled trial of the efficacy of a training walking program in patients recovering from abdominal aortic aneurysm surgery. Adv Clin Exp Med. 2016;25(6):1241-371. http://dx.doi.org/10.17219/acem/62239. PMid:28028979. http://dx.doi.org/10.17219/acem/62239...
“Low risk”	Comment: blinding of outcome assessment was described and seems to be appropriate.
Blinding of outcome assessment (detection bias) – VEF1	Quote: described as a single blinded study. Replied by e-mail 09/27/2017: “Measurement of gait parameters and spirometry was evaluated by physiotherapist from the Department of Rehabilitation. Routine physiotherapy and training walking in three groups was conducted by physiotherapist from the department of General and Vascular Surgery.”³⁰30 Wnuk BR, Durmała J, Ziaja K, Kotyla P, Woźniewski M, Błaszczak E. A controlled trial of the efficacy of a training walking program in patients recovering from abdominal aortic aneurysm surgery. Adv Clin Exp Med. 2016;25(6):1241-371. http://dx.doi.org/10.17219/acem/62239. PMid:28028979. http://dx.doi.org/10.17219/acem/62239...
“Low risk”	Comment: blinding of outcome assessment was described and seems to be appropriate.
Incomplete outcome data (attrition bias) – all-cause mortality	Not assessed
Incomplete outcome data (attrition bias) – number of patients with aortic rupture	Not applicable
Incomplete outcome data (attrition bias) – aneurysm growth	Not applicable
Incomplete outcome data (attrition bias) – quality of life	Not assessed
Incomplete outcome data (attrition bias) – number of patients referred for surgery	Not applicable
Incomplete outcome data (attrition bias) – peri-operative complications	Not applicable
Incomplete outcome data (attrition bias) – postoperative complications	Not assessed
Incomplete outcome data (attrition bias) – cardiovascular mortality	Not assessed
Incomplete outcome data (attrition bias) – hospital stay	Comment: there were 27.41% dropouts and we do not what the impact of this would be on results and conclusions.
“Unclear risk”
Incomplete outcome data (attrition bias) – VEF1	Comment: there were 27.41% dropouts and we do not what the impact of this would be on results and conclusions.
“Unclear risk”
Selective reporting (reporting bias)	Comment: the proposed outcomes were described and seem to be appropriate.
“Low risk”
Other bias	Comment: describes balance between groups at baseline. No other source of bias detected.
“Low risk”

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[1] Conflicts of interest: No conflicts of interest declared concerning the publication of this article.