A meta-analysis of clinical studies of statins for prevention of abdominal aortic aneurysm expansion

BackgroundDespite the absence of a relationship between cholesterol and abdominal aortic aneurysm (AAA) expansion, there is evidence from a number of studies to suggest that statin therapy may influence AAA expansion, presumably through pleiotropic effects. To confirm whether statin therapy is associated with less AAA expansion, we performed a meta-analysis of clinical controlled studies of statin therapy for prevention of AAA expansion.MethodsTo identify all clinical studies of statin therapy vs control (no statins) enrolling patients with small (≤55 mm) AAA, MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched. For each study, data regarding AAA expansion in both the statin and control groups were used to generate standardized mean differences (SMDs; <0 favoring statin therapy; >0 favoring control) and 95% confidence intervals (CIs). Study-specific estimates were combined using inverse variance-weighted averages of logarithmic SMDs in fixed-effects and random-effects models.ResultsWe identified five clinical controlled studies of statin therapy vs control enrolling patients with small AAA, including no randomized and five observational studies. Our meta-analysis included data on 697 patients with small AAA received statin therapy or no statins. Pooled analysis demonstrated that statin therapy was statistically significantly associated with less expansion rates (random-effects SMD, −0.50; 95% CI, −0.75 to −0.25; P = .0001). There was statistically significant trial heterogeneity of results (P = .03). Exclusion of any single trial from the analysis did not substantively alter the overall result of our analysis. There was no evidence of significant publication bias (P = .81).ConclusionStatin therapy is associated with less expansion rates in patients with small AAA. To confirm our results and more accurately assess the effect of statins on AAA expansion, a large randomized trial is needed. Despite the absence of a relationship between cholesterol and abdominal aortic aneurysm (AAA) expansion, there is evidence from a number of studies to suggest that statin therapy may influence AAA expansion, presumably through pleiotropic effects. To confirm whether statin therapy is associated with less AAA expansion, we performed a meta-analysis of clinical controlled studies of statin therapy for prevention of AAA expansion. To identify all clinical studies of statin therapy vs control (no statins) enrolling patients with small (≤55 mm) AAA, MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched. For each study, data regarding AAA expansion in both the statin and control groups were used to generate standardized mean differences (SMDs; <0 favoring statin therapy; >0 favoring control) and 95% confidence intervals (CIs). Study-specific estimates were combined using inverse variance-weighted averages of logarithmic SMDs in fixed-effects and random-effects models. We identified five clinical controlled studies of statin therapy vs control enrolling patients with small AAA, including no randomized and five observational studies. Our meta-analysis included data on 697 patients with small AAA received statin therapy or no statins. Pooled analysis demonstrated that statin therapy was statistically significantly associated with less expansion rates (random-effects SMD, −0.50; 95% CI, −0.75 to −0.25; P = .0001). There was statistically significant trial heterogeneity of results (P = .03). Exclusion of any single trial from the analysis did not substantively alter the overall result of our analysis. There was no evidence of significant publication bias (P = .81). Statin therapy is associated with less expansion rates in patients with small AAA. To confirm our results and more accurately assess the effect of statins on AAA expansion, a large randomized trial is needed.