Aspirin is a primary preventative measure against cardiovascular disease (CVD), but few studies have adequately quantified bleeding risks in untreated patients without CVD in order to inform aspirin use. In a study published in Annals of Internal Medicine, a team of researchers in New Zealand described novel prognostic models for assessing bleeding risk in this patient population.

A total of 385,191 patients between 30 and 79 years old who did not have a history of CVD or prior antiplatelet treatment were enrolled in the study. National databases were used to obtain data on CVD risk, demographic characteristics, medical history, clinical and laboratory measurements, and medication for all patients. Primary outcome was first major bleeding event associated with hospitalization or death. Cox proportional hazards modeling was used to develop sex-specific prediction models.

During the course of the study, there were 4442 major bleeding events, and 313 (7%) of these were fatal. This yielded a crude incidence of 2.62 and 2.84 major bleeding events per 1000 person-years among women and men, respectively.

Established bleeding risk factors, including cancer, prior bleeding, use of certain medications, and chronic liver disease, were found to be associated with increased bleeding risk. Other risk factors included older age, level of socioeconomic deprivation, smoking, and diabetes in both men and women and Asian ethnicity compared with European ethnicity in men (hazard ratio [HR], 1.46).

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Both sex-specific prediction models demonstrated good calibration, though bleeding risk in women was often underestimated by up to 0.7%. The estimated bleeding risk at 5 years was 1.3% (interquartile range [IQR], 0.8%-1.5%) for women and 1.4% (IQR, 0.7%-1.6%) for men.

The authors cautioned that the generalizability of their findings to patient populations outside New Zealand was uncertain, and that traumatic and postprocedural bleeding, which were excluded from this report, may lead to underestimation of overall bleeding risk. However, they concluded that their prognostic models may be used to estimate bleeding risk in patients considering the use of aspirin for the prevention of CVD.


1. Selak V, Jackson R, Poppe K, et al. Predicting bleeding risk to guide aspirin use for the primary prevention of cardiovascular disease [published online February 26, 2019]. Ann Intern Med. doi: 10.7326/M18-2808