1. From a microsimulation decision analysis, aspirin as primary prevention for cardiovascular disease and colorectal cancer showed a positive lifetime benefit in patients of both sexes and baseline risk group aged 40 to 60.
2. The risk of gastrointestinal (GI) bleeding and hemorrhagic stroke was highest in patients aged 70 to 79 with a 10-year cardiovascular risk of 20% or less.
Evidence Rating Level: 2 (Good)
Study Rundown: While strong evidence exists to support the effectiveness of aspirin in secondary prevention of complications from heart disease and stroke, evidence for the net benefit of aspirin in preventing cardiovascular disease (CVD) and colorectal cancer (CRC) is less clear. This study evaluates three recent systematic reviews conducted on behalf of the U.S. Preventive Services Task Force (USPSTF) to evaluate the benefits and harms of long-term aspirin use in primary prevention for CVD and CRC. Collectively, the reviews affirmed a positive lifetime benefit in aspirin use for all sex and baseline CVD risk groups aged 40 to 60, while a negative lifetime benefit was observed for patients of all risk levels aged 70 to 79. Additionally, aspirin’s protective effect for CRC was lowest when aspirin was initiated at older ages. This study may be limited by its estimates of how age, sex, aspirin, and other possible risk factors interact to affect GI bleeding and case-fatality rates. Overall, the study suggests that while adults aged 40 to 60 may benefit from aspirin primary prevention of CVD and CRC, the harms might outweigh the benefits in an older population.
Relevant Reading: Aspirin for the prevention of colorectal cancer
In-Depth [microsimulation model]: In this analysis, findings from three recent reviews conducted by the USPTSF were evaluated to compare the net benefits of aspirin in primary prevention across different age groups, CVD risk groups, and sexes. CVD risk was estimated using the American College of Cardiology/American Heart Association risk calculator for the first hard atherosclerotic CVD event. In general, the magnitude of net life years and quality adjusted life years (QALYs) were greater in both younger populations and those with higher 10-year CVD risk at initiation. The estimated lifetime net difference in QALYs from using aspirin for primary prevention of CVD and CRC was positive for all baseline CVD risk groups aged 40 to 69 (range 7.4 to 107.9 QALYs per 1000 persons). This population did not have elevated bleeding risk. In contrast, for patients aged 70 to 79 with a 10-year CVD risk of 20% or less the lifetime net difference in QALYs was negative (range –1.3 to –26.1 QALYs per 1000 persons).
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