Background/Aims Aspirin is a cornerstone of primary cardiovascular disease prevention, but little is known about aspirin use patterns in primary care populations. Aspirin pharmacoepidemiology research presents some particular challenges within the HMO Research Network because aspirin is typically obtained over-the-counter and does not routinely appear in pharmacy claims data. This study leveraged electronic health records from the Marshfield Clinic to identify demographic, clinical, and geographic predictors of aspirin use in adults without cardiovascular disease.

Methods A cross-sectional study was used with years 2010–2012 data from 45–79 year old adults in the Marshfield Epidemiologic Study Area. Individuals who reported regular use (daily or every other day) of aspirin-containing medications during their most recent ambulatory encounter, or had an aspirin contraindication, were considered adherent to aspirin therapy.

Results Per national guideline, there were 6,950 adults in the target population who were clinically indicated for aspirin therapy for primary cardiovascular disease prevention. Aspirin was underutilized in this population overall, with less than half of all clinically indicated adults adherent to aspirin therapy. Statistically adjusted models found that individuals who were younger, female, not covered by health insurance, did not visit a medical provider regularly, were not obese, or did not have diabetes were least likely to use aspirin. In addition, aspirin use was less common in northeastern communities within the Marshfield Clinic service area.

Conclusions Demographic patterns of aspirin use in this study were largely consistent with previous findings, noting several aspirin use disparities in central Wisconsin adults without cardiovascular disease. Aspirin use was particularly low in those without diabetes and/or without regular physician contact. The methods outlined here on using electronic health records to conduct aspirin pharmacosurveillance can be adopted and refined by other HMO Research Network partners to optimize future cardiovascular disease (primary) prevention initiatives.