Aspirin after myocardial infarction: the importance of over-the-counter use

Background. Regular aspirin is beneficial after myocardial infarction (MI). Community-based surveys appear to show unsatisfactory uptake of aspirin after MI. This could be due to over-the-counter (OTC) use not being recorded. In a pilot study in one practice, 39% of patients on aspirin after MI used OTC preparations. In addition, women and older patients were less likely to use aspirin. Objectives. We aimed to describe aspirin use following MI in general practices in West London, including regimens and OTC use, and to demonstrate any association between aspirin use and gender, age or social class. Methods. We used a postal questionnaire survey. The setting was a random sample of six general practices in Eating, Hammersmith and Hounslow Health Authority who use Egton Medical Information Systems (EMIS) to store morbidity data. The subjects were registered patients with a history of MI. The main outcome measures were questionnaire data on aspirin use, regimen, OTC use, prescription charge exemption, age, gender, ethnic group and social class. Results. The prevalence of previously recorded MI in all age groups was 0.64%. The response rate was 89%. Regular aspirin was used by 80%. Of these, 22% use OTC aspirin. OTC use was significantly more common in those paying prescription charges. Aspirin use was not associated with gender, age or social class. Conclusion. This study demonstrated a high uptake of aspirin among patients with previous MI as recorded by computer. OTC aspirin use was significant, and should be enquired about and recorded.