A primary care study has shown that many patients continue to use aspirin for primary prevention, with almost two thirds doing so on the advice of their family doctor, despite studies showing an unfavourable risk/benefit profile.

The study was a cross-sectional, self-reported, waiting room questionnaire in two North American primary care clinics. Patients were 50 years of age or older.

Data were collected on the overall prevalence of aspirin use, the proportion used for primary or secondary cardiovascular prevention, and use by patient age and sex. The proportion who initiated aspirin on the advice of a physician and patient beliefs about the role of aspirin were also recorded.

Overall 807 patients completed the questionnaire with a response rate of 89.1%.

A total of 318 patients (39.8%) were taking aspirin regularly, 274 (87.0%) of whom took it for the prevention of cardiovascular disease. More than half (53.1%) of these took it for primary prevention and 46.9% for secondary prevention. In the primary prevention cohort 62.0% took aspirin on the advice of their family doctor.

However, of the 200 patients who had underlying cardiovascular disease only 62.5% took aspirin.

Nearly three quarters of patients (70.9%) who took aspirin for cardiovascular prevention believed that the benefits outweighed the risks. This view did not differ between those patients taking it for primary and those taking it for secondary prevention.

Low dose aspirin has an established role in the secondary prevention of cardiovascular disease but the picture is far from clear in primary prevention. Many professional societies and guidelines now discourage the use of aspirin in people with no underlying cardiovascular disease. This is the result of a number of large studies showing an unfavourable risk/benefit profile in such patients.

Patients can of course continue to self-medicate with aspirin and physicians are often slow to change historical patterns of prescribing or may remain unconvinced by the growing evidence base.

The authors conclude that aspirin use is common and more than half take it for the primary prevention of cardiovascular disease with primary care physicians continuing to support this strategy.

They postulate that more education as to the risk/benefit profile of aspirin is required for both patients and doctors. This would help to target aspirin use to those patients who are most likely to derive the greatest overall benefit.

Dr Peter Savill