A Cochrane review included 4 studies with a total of 3 314 subjects with small (diameter 4.0 to 5.5 cm) asymptomatic aneurysms in the abdominal aorta (AAA). Two studies compared surveillance (regular, routine ultrasounds to check for aneurysm growth) with immediate open repair and 2 studies compared surveillance with immediate endovascular repair. Among the patients randomised to surveillance, the aneurysm was repaired if it was enlarging, reached 5.5 cm in diameter, or became symptomatic.
The four trials showed an early survival benefit in the surveillance group because of the number of deaths within 30 days of surgery (operative mortality) but no significant differences in long-term survival (table ). Some 31% to 75% of the participants randomised to surveillance eventually had the aneurysm repaired. A pooled analysis of participant-level data from 2 studies (with a maximum follow-up of 7 to 8 years) showed no statistically significant difference in survival between immediate open repair and surveillance (propensity score-adjusted HR 0.99, 95% CI 0.83 to 1.18), and that this lack of treatment effect did not vary by AAA diameter (P = 0.39) or participant age (P = 0.61). The meta-analysis of mortality at one year for the endovascular trials likewise showed no significant association (RR at one year 1.15, 95% CI 0.60 to 2.17). Quality-of-life results among trials were conflicting.
| Study (intervention) | Mean follow-up | HR (95% CI) | Mortality (immediate repair) | Mortality (surveillance) | |
|---|---|---|---|---|---|
| * HR for mortality between surveillance versus immediate repair | |||||
| UKSAT (surgery) | 10 years | 0.88 (0.75 to 1.02) | 63.9% | 67.3% | |
| ADAM (surgery) | 4.9 years | 1.21 (0.95 to 1.54) | 25.1% | 21.5% | |
| CAESAR (endovascular repair) | 32.4 months | 0.76 (0.30 to 1.93)* | 14.5% | 10.1% | |
| PIVOTAL (endovascular repair) | 20 months | 1.01 (0.49 to 2.07) | 4.1% | 4.1% | |
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