Outcomes of one-time screening for AAA using ultrasonography for men aged 65 years and older*
| Outcome and followup period | No. of studies | Cases/received procedure screened patients (%) | Cases/received procedure control patients (%) | Risk ratio (95% CI) | Absolute per 1000 | Absolute risk reduction, % | Absolute risk increase, % | Number needed to screen (95% CI) | Quality of evidence |
|---|---|---|---|---|---|---|---|---|---|
| AAA-related mortality 3–5 yr22 | 4 | 102/62 729 (0.16) | 182/62 847 (0.29) | 0.57 (0.44–0.72) | 1.3 fewer (from 0.8 fewer to 1.6 fewer) | 0.13 | 796 (621–1242) | ⊕⊕⊕○ MODERATE† | |
| AAA-related mortality 13–15 yr22,24 | 4 | 380/62 460 (0.61) | 588/62 469 (0.94) | 0.66 (0.47–0.93) | 3.2 fewer (from 0.6 fewer to 5.0 fewer) | 0.32 | 311 (199–1595) | ⊕⊕⊕○ MODERATE† | |
| All-cause mortality 3–5 yr22 | 4 | 7453/62 729 (11.9) | 7953/62 847 (12.7) | 0.95 (0.88–1.02) | 7.0 fewer (from 15.7 fewer to 2.5 more) | NS | – | ⊕⊕○○ LOW‡ | |
| All-cause mortality 13–15 yr22,24 | 4 | 28 474/62 460 (45.6) | 28 899/62 469 (46.3) | 0.99 (0.98–1.00) | 6.1 fewer (from 0.7 fewer to 11.4 fewer) | 0.61 | 164 (88–1441) | ⊕⊕⊕○ MODERATE† | |
| Rupture of an AAA 3–5 yr22 | 4 | 117/62 729 (0.19) | 218/62 847 (0.35) | 0.52 (0.35–0.79) | 1.6 fewer (from 0.7 fewer to 2.3 fewer) | 0.16 | 606 (442–1387) | ⊕⊕⊕○ MODERATE† | |
| Rupture of an AAA 13–15 yr22,24 | 4 | 415/62 460 (0.66) | 674/62 469 (1.1) | 0.65 (0.51–0.82) | 3.8 fewer (from 1.9 fewer to 5.2 fewer) | 0.38 | 264 (191–515) | ⊕⊕⊕○ MODERATE† | |
| AAA procedures 3–5 yr22 | 4 | 554/62 729 (0.88) | 252/62 847 (0.4) | 2.16 (1.82–2.57) | 4.7 more (from 3.3 more to 6.3 more) | 0.47 | 215 (159–305) | ⊕⊕⊕○ MODERATE† | |
| AAA procedures 13–15 yr22,24 | 4 | 1408/62 460 (2.3) | 1029/62 469 (1.6) | 1.35 (1.17–1.57) | 5.9 more (from 2.8 more to 9.4 more) | 0.58 | 171 (107–358) | ⊕⊕⊕○ MODERATE† | |
| Elective procedures 3–5 yr22 | 4 | 505/62 729 (0.81) | 162/62 847 (0.26) | 3.25 (2.13–4.96) | 5.8 more (from 2.9 more to 10.2 more) | 0.58 | 172 (98–342) | ⊕⊕⊕○ MODERATE† | |
| Elective procedures 13–15 yr22,24 | 4 | 1266/62 460 (2.0) | 754/62 469 (1.2) | 1.83 (1.29–2.59) | 10.0 more (from 3.6 to 19.2 more) | 1.00 | 100 (52–281) | ⊕⊕⊕○ MODERATE† | |
| Emergency procedures 3–5 yr22,25 | 4 | 44/62 729 (0.07) | 90/62 847 (0.14) | 0.50 (0.29–0.86) | 0.7 fewer (from 0.2 fewer to 1.0 fewer) | 0.07 | – | 1389 (980–4975) | ⊕⊕⊕○ MODERATE† |
| Emergency procedures 13–15 yr24,25 | 4 | 142/62 460 (0.23) | 275/62 469 (0.44) | 0.52 (0.42–0.63) | 2.1 fewer (from 1.6 fewer to 2.5 fewer) | 0.21 | – | 471 (394–622) | ⊕⊕⊕○ MODERATE† |
| 30-day mortality, after any AAA procedures 3–5 yr22,25 | 3 | 29/501 (5.8) | 41/221 (18.6) | 0.31 (0.20–0.48) | 128.0 fewer (from 95.7 fewer to 149.0 fewer) | 12.83 | – | 8 (7–10) | ⊕⊕⊕○ MODERATE† |
| 30-day mortality, after any AAA procedures 13–15 yr24,25 | 3 | 92/1,299 (7.1) | 119/941 (12.6) | 0.55 (0.39–0.80) | 56.3 fewer (from 25.6 fewer to 77.7 fewer) | 5.63 | – | 18 (13–39) | ⊕⊕⊕○ MODERATE† |
Note: AAA = abdominal aortic aneurysm, CI = confidence interval, NS = not significant.
↵* The estimated absolute risk reduction/increase is from pooled results of the trials on AAA screening. The prevalence of AAA in screened populations of men aged 65 years and older at the time of the trials was 3.9% to 7.2%, with more recent population-based estimates of prevalence in countries similar to Canada ranging from 1.5% to 1.7%, reducing the benefit of screening.
↵† Downgraded to moderate owing to serious risk of bias.
↵‡ Downgraded to low owing to serious risk of bias and imprecision.