Association between aspirin and upper gastrointestinal complications: Systematic review of epidemiologic studies

Aims Because of the widespread use of aspirin for prevention of cardiovascu lar diseases, side-effects associated with thromboprophylactic doses are of interest. This Study summarizes the relative risk (RR) for serious upper g astrointestinal complications (UGIC) associated with aspirin exposure in ge neral and with specific aspirin doses and formulations in particular. Methods After a systematic review. 17 original epidemiologic studies publis hed between 1990 and 2001 were selected according to predefined criteria. H eterogeneity of effects was explored. Pooled estimates were calculated acco rding to different Study characteristics and patterns of aspirin use. Results The overall relative risk of UGIC associated with aspirin use was 2 .2 (95% confidence interval (CI): 2.1, 2.4) for cohort Studies and nested c ase-control studies and 3.1 (95%, CI: 2.8, 3.3) for non-nested case-control studies. Original Studies found a dose-response relationship between UGIC and aspirin, although the risk was still elevated for doses lower or tip to 300 mg day(-1). The summary RR was 2.6 (95% CI: 2.3, 2.9) for plain, 5.3 ( 95% CI: 3.0. 9.2) for buffered, and 2.4 (95% CI: 1.9, 2.9) for enteric-coat ed aspirin formulations. Conclusions Aspirin was associated with UGIC even when used at low doses or in buffered or enteric-coated formulations. The latter findings may be par tially explained by channeling of susceptible patients to these formulation s.