Daily aspirin may benefit many patients without existing cardiovascular disease

The benefits of aspirin may outweigh the risks for many patients without known cardiovascular disease (CVD). Such patients could be identified by using a personalized benefit-harm analysis, which could inform discussions between doctors and patients. The findings are published in Annals of Internal Medicine.
Aspirin reduces the risk for CVD in at-risk patients, but also increases the risk for bleeding. It is not clear if the benefits of aspirin outweigh the risks for patients without known CVD.
Researchers from the University of Auckland, New Zealand studied 245,028 persons (43.6 percent women) aged 30 to 79 years without established CVD to identify persons for whom aspirin would probably result in a net benefit. The net effect of aspirin was calculated for each participant by subtracting the number of CVD events likely to be prevented from the number of major bleeds likely to be caused over 5 years. The data were derived from PREDICT, a well-characterized web-based decision support program integrated with electronic primary care practice management systems in New Zealand. The researchers found that 2.5 percent of women and 12.1 percent of men without established CVD were likely to derive net benefit from aspirin treatment for 5 years if a hospitalization or death due to an acute CVD event was considered equivalent to a hospitalization or death due to an acute major bleed. These percentages increased to 21 percent of women and 41 percent of men when one CVD event was assumed to be equivalent to two major bleeds.
The author of an editorial from the Cardiovascular Institute, Rutgers Robert Wood Johnson Medical School cautions that the study findings may not apply to populations outside New Zealand. Also, participants over the age of 79 were not included in the analysis. The author points to the diversity of findings in several aspirin studies to conclude that making firm, evidence-based recommendations for aspirin use for primary prevention is difficult.