The role of aspirin in primary prevention of cardiovascular disease


Background: Previous studies have shown that aspirin reduces the relative risk of cardiovascular disease (CVD) but also increases the relative risk of bleeding. It is unclear if there are patients without known CVD in whom the absolute risk reduction of CVD outweighs the absolute risk of bleeding. Prognostic CVD and bleeding risk models allow for an assessment of absolute risks and primary preventive interventions.

Study design: Individualized risk-benefit analysis based on sex-specific risk scores and estimates from PREDICT cohort data.

Setting: Primary care practices in New Zealand.

Synopsis: Using the New Zealand–based PREDICT online tool, 245,048 patients had their CVD risk assessed and did not meet exclusion criteria. The online tool predicts CVD events avoided and bleeding events caused by aspirin. When one CVD event was equivalent to one major bleeding event, 2.5% of women and 12.1% of men were classified as benefiting from aspirin (more CVD events avoided than bleeding events caused). When one CVD event was equivalent to two major bleeding events, 21.4% of women and 40.7% of men were classified as benefiting from aspirin. The net-benefit subgroups were older, and had higher baseline 5-year CVD risk, fewer risk factors for bleeding, higher systolic blood pressure, and a higher total cholesterol to HDL cholesterol ratio. Ethnicity and socioeconomic index also influenced benefit or harm.

With use of the upper and lower limits of 95% confidence intervals for models, there were considerable ranges of benefit versus harm. Sex-specific risk scores and meta-analysis have intrinsic uncertainties and results potentially not generalizable outside New Zealand population. Ultimate decision to use aspirin requires shared decision making.

Bottom line: Some patients are likely to derive a net benefit from aspirin for primary prevention of CVD. Risk-benefit models with online tools can help providers and patients estimate these factors to inform shared decision making.

Citation: Selak V et al. Personalized prediction of cardiovascular benefits and bleeding harms for aspirin for primary prevention, a benefit-harm analysis. Ann Intern Med. 2019;71(8):529-39.

Dr. Rupp is a hospitalist and clinical instructor of medicine at the University of Utah, Salt Lake City.

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