A Meta-Analysis of Randomized Controlled Trials of Aspirin in Primary Prevention of Cardiovascular Disease.

Abstract 174

Primary prevention with aspirin reduces the risk of non-fatal cardiovascular events but has not been demonstrated to reduce mortality. We performed an updated meta-analysis of randomised controlled trials of aspirin in primary prevention to obtain best estimates of the benefits and harm of aspirin compared with no aspirin with a focus on mortality. Eligible articles were identified by computerized search of MEDLINE, EMBASE, Cochrane library and CINAHL databases, review of bibliographies of relevant publications and a related article search using PubMed. The outcomes of interest included all cause mortality, cardiovascular mortality, the composite of myocardial infarction, stroke or death, and bleeding. 2 reviewers independently extracted study information and data. Data were pooled from individual trials using the DerSimonian-Laird random-effects model and results are presented as relative risk (RR) and 95% confidence intervals (CI). 8 studies comprising a total of 96,726 subjects were included. Aspirin reduced all-cause mortality (RR 0.94; 95%CI 0.88–1.00), the composite of myocardial infarction, stroke or cardiovascular death (RR 0.87; 95%CI 0.82–0.93), and myocardial infarction (RR 0.8; 95%CI 0.66–0.98) but did not significantly reduce cardiovascular mortality (RR 0.94; 95%CI 0.82–1.08) or stroke (RR 0.93; 95%CI 0.81–1.07). Aspirin increased the risk of major bleeding (RR; 1.69 95%CI 1.38–2.08), gastrointestinal bleeding (RR 1.38; 95%CI 1.16–1.65) and hemorrhagic stroke (RR 1.36; 95%CI 1.01–1.84). There was no interaction between subjects with or without diabetes for the outcomes of all cause mortality, cardiovascular mortality, the composite of myocardial infarction, stroke or death. Aspirin therapy in subjects with no prior history of cardiovascular disease reduces the risk of cardiovascular events, myocardial infarction and overall mortality. These benefits are achieved at the expense of increased bleeding.