Article type
Year
Abstract
Background: We conducted a systematic review for the US Preventive Services Task Force to estimate the benefits and harms of aspirin chemoprophylaxis in patients with different levels of risk for cardiovascular disease (CVD).
Methods: We searched MEDLINE from 1966 to January 2000 and the Cochrane Collaboration registry of clinical trials to identify randomized trials of at least one year duration that examined aspirin chemoprophylaxis in patients without previously known CVD. We constructed evidence tables and performed a meta-analysis using the DerSimonian and Laird random effects model. We also searched for other systematic reviews, trials, and observational data examining the adverse events associated with aspirin use. Finally, we used estimates from our systematic review to model the consequences of using aspirin prophylaxis for patients with different levels of baseline CVD risk.
Results: Our initial search strategy yielded 1240 abstracts. We identified four trials of the efficacy of aspirin and nine articles about adverse effects that met our inclusion criteria. Aspirin chemoprophylaxis reduced the risk for the combined endpoint of non-fatal myocardial and fatal coronary heart disease by 28% (summary OR = 0.72, 95% CI 0.59, 0.89). Overall, the incidence of all strokes was not affected (summary OR = 1.06, 95% CI 0.89, 1.26). Total mortality was also not affected (summary OR 0.94, 95% CI 0.85, 1.04). Estimates of harms included an absolute risk increase of 1-2 hemorrhagic strokes per 1,000 persons treated for 5 years and an excess of 1 to 2 major gastrointestinal bleeds per 1,000 person years of exposure.
Conclusions: Aspirin chemoprophylaxis reduces myocardial infarction but increases hemorrhagic stroke and gastrointestinal bleeding. For patients with risks of CVD events greater than 5% over 5 years, the number of myocardial infarctions prevented exceeds the number of hemorrhagic strokes and major GI bleeds precipitated. The numbers of myocardial infarctions prevented and adverse events precipitated are closer to being equal in patients with CVD risk of 1-5% over 5 years; the adverse events probably exceed the beneficial reduction in CVD events when risk is less than 1% over 5 years. Physicians and patients should use the patient's calculated risk of CVD and the patient's utilities for the different health outcomes to tailor decisions about prophylaxis, especially for patients with intermediate levels of CVD risk.
Methods: We searched MEDLINE from 1966 to January 2000 and the Cochrane Collaboration registry of clinical trials to identify randomized trials of at least one year duration that examined aspirin chemoprophylaxis in patients without previously known CVD. We constructed evidence tables and performed a meta-analysis using the DerSimonian and Laird random effects model. We also searched for other systematic reviews, trials, and observational data examining the adverse events associated with aspirin use. Finally, we used estimates from our systematic review to model the consequences of using aspirin prophylaxis for patients with different levels of baseline CVD risk.
Results: Our initial search strategy yielded 1240 abstracts. We identified four trials of the efficacy of aspirin and nine articles about adverse effects that met our inclusion criteria. Aspirin chemoprophylaxis reduced the risk for the combined endpoint of non-fatal myocardial and fatal coronary heart disease by 28% (summary OR = 0.72, 95% CI 0.59, 0.89). Overall, the incidence of all strokes was not affected (summary OR = 1.06, 95% CI 0.89, 1.26). Total mortality was also not affected (summary OR 0.94, 95% CI 0.85, 1.04). Estimates of harms included an absolute risk increase of 1-2 hemorrhagic strokes per 1,000 persons treated for 5 years and an excess of 1 to 2 major gastrointestinal bleeds per 1,000 person years of exposure.
Conclusions: Aspirin chemoprophylaxis reduces myocardial infarction but increases hemorrhagic stroke and gastrointestinal bleeding. For patients with risks of CVD events greater than 5% over 5 years, the number of myocardial infarctions prevented exceeds the number of hemorrhagic strokes and major GI bleeds precipitated. The numbers of myocardial infarctions prevented and adverse events precipitated are closer to being equal in patients with CVD risk of 1-5% over 5 years; the adverse events probably exceed the beneficial reduction in CVD events when risk is less than 1% over 5 years. Physicians and patients should use the patient's calculated risk of CVD and the patient's utilities for the different health outcomes to tailor decisions about prophylaxis, especially for patients with intermediate levels of CVD risk.