Summary of findings 1. Early open repair compared to ultrasound surveillance for small asymptomatic abdominal aortic aneurysms.

Early open repair compared to ultrasound surveillance for small asymptomatic AAA
Patient or population: small asymptomatic AAA Setting: hospital Intervention: early open repair (open surgery) Comparison: ultrasound surveillance
Outcomes	Anticipated absolute effects* (95% CI)		Relative effect (95% CI)	№ of participants (RCTs)	Certainty of the evidence (GRADE)	Comments
	Risk with ultrasound surveillance	Risk with early repair
Mortality (follow‐up to 6 years)	Study population		HR 0.99 (CI 0.83 to 1.18)a	2226 (2 RCTs)	⊕⊕⊕⊕ High	No clear evidence to support a difference in survival between early open repair and surveillance.
	0.28 (0.25 to 0.31)	0.30 (0.27 to 0.33)
Costs (per participant) (follow‐up to 18 months)	GBP 3914	GBP 4978	MD GBP 1064higher (796.32 higher to 1331.68 higher)	1090 (1 RCT)	⊕⊕⊕⊝ Moderateb	In UKSAT, the mean health service costs per participant were higher in the surgery than the surveillance group, and remained higher at 12‐years of follow‐up. This estimate accounted for semi‐annual surveillance visits, aneurysm repair, and any associated follow‐up.
QoLc (follow‐up to 24 months)	See comment			2226 (2 RCTs)	—	In UKSAT, early‐surgery survivors reported minor improvements in MOS‐20 based current health perceptions and less negative changes in bodily pain (after 1 year). In ADAM, early‐surgery and surveillance groups did not differ for most SF‐36 scales, but the study authors reported that the early‐surgery group had better scores for general health and lower scores for vitality (during the first 2 years); more participants became impotent after early repair compared with surveillance (after 1 year); maximum activity level declined more rapidly over time in the early‐repair group.
Aneurysm rupture (follow‐up 6 years )	See comment			2226 (2 RCTs)	—	In UKSAT, there were 25 ruptures – at least 17 in the surveillance group vs ≥ 6 in the early‐repair group (2 with emergency repairs, group unknown). 15/25 had an aneurysm diameter < 5.5 cm at previous follow‐up. In ADAM, there were 13 ruptures – 11 in the surveillance group and 2 in the early‐repair group (last diameter preceding rupture was not reported).
*The risk in the intervention 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). AAA: abdominal aortic aneurysm; CI: confidence interval; EVAR: endovascular aneurysm repair; GBP: Great British pounds; HR: hazard ratio; MD: mean difference; MOS‐20: 20‐item Medical Outcomes Study; QoL: quality of life; RCT: randomised controlled trial; SF‐36: 36‐item Short Form.
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.

^aFrom pooled individual participant analysis (estimated from Figure 1 in Filardo 2013).
^bDowngraded one level for imprecision due to evidence from one trial only.
^cUKSAT measured QoL with the MOS‐20 short‐form, ADAM used the SF‐36 form.