title: A further meta-analysis of population-based screening for abdominal aortic aneurysm.
abstract: OBJECTIVE
  It remains unclear whether population-based screening for abdominal aortic aneurysm (AAA) in men reduces all-cause long-term mortality. We performed an updated meta-analysis of randomized controlled trials of AAA screening for prevention of long-term mortality in men.
  
  
  METHODS
  To identify all randomized controlled trials of population-based AAA screening with long-term (≥ 10 year) follow-up in men, MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials were searched through June 2009. Data regarding AAA-related and all-cause mortality (including Cox regression hazard ratios [HRs] and 95% confidence intervals [CIs]) were abstracted from each individual study. For each study, data regarding mortality in both the screening and control groups were used to generate odds ratios (ORs) and 95% CIs. Study-specific estimates were combined using inverse variance-weighted averages of logarithmic ORs or HRs (or risk ratios where no HR was reported) in both fixed- and random-effects models.
  
  
  RESULTS
  Our search identified four randomized controlled trials of population-based AAA screening with long-term follow-up in men aged ≥ 65 years. Pooled analysis demonstrated a statistically significant reduction in AAA-related mortality (random-effects OR, 0.55; 95% CI, 0.36 to 0.86; P = .008; P for heterogeneity = .01; absolute risk reduction [ARR], 4 per 1000; number needed to screen [NNS], 238; random-effects HR, 0.55; 95% CI, 0.35 to 0.86; P = .009; P for heterogeneity = .009) and revealed a statistically nonsignificant reduction (but a strong trend toward a significant reduction) in all-cause mortality (fixed-effects OR, 0.98; 95% CI, 0.95 to 1.00 [1.001]; P = .06; P for heterogeneity = .93; ARR, 5 per 1000; NNS, 217; fixed-effects HR, 0.98; 95% CI, 0.96 to 1.00 [1.0001]; P ≥ .05 [P = .052]; P for heterogeneity = .74) with AAA screening relative to control.
  
  
  CONCLUSIONS
  The results of our analysis suggest that population-based screening for AAA reduces AAA-related long-term mortality by 4 per 1000 over control in men aged ≥ 65 years. Whereas, screening for AAA shows a strong trend toward a significant reduction in all-cause long-term mortality by 5 per 1000, which does not narrowly reach statistical significance.
authors.affiliation: Department of Cardiovascular Surgery, Shizuoka Medical Center, Shizuoka, Japan. kfgth973@ybb.ne.jp
authors.forename: Hisato
authors.initials: H
authors.lastname: Takagi
authors.forename: Shin-nosuke
authors.initials: SN
authors.lastname: Goto
authors.forename: Masafumi
authors.initials: M
authors.lastname: Matsui
authors.forename: Hideaki
authors.initials: H
authors.lastname: Manabe
authors.forename: Takuya
authors.initials: T
authors.lastname: Umemoto
mesh_terms: D000367:Age Factors; D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000175:diagnosis / Q000401:mortality / Q000517:prevention & control*; D019317:Evidence-Based Medicine; D006801:Humans; D016014:Linear Models; D008297:Male; D008403:Mass Screening / Q000379:methods; D054526:Men's Health; D016017:Odds Ratio; D011314:Preventive Health Services; D016016:Proportional Hazards Models; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D016019:Survival Analysis