Epidemiological feasibility of cardiovascular primary prevention in general practice: a trial of vitamin E and aspirin. Collaborative group of the Primary Prevention Project.

BACKGROUND: Antioxidant and antiplatelet drugs might help prevent the progression of atherosclerosis or its thrombotic consequences as adjuncts to specific treatment of cardiovascular risk factors.

METHODS: Primary health care may be the ideal setting for screening people at risk, for monitoring the evolution of risk factors and for minimizing their clinical consequences. We therefore estimated the fraction of the general population who would be suitable candidates for preventive strategies because of the presence of at least one known cardiovascular risk factor. We used an ad-hoc protocol in a random sample of people aged 50-75 years who consulted their general practitioner for any reason over a predefined 2-week period.

RESULTS: Complete information was available for 2522 participants (94.3% of 2674 patients screened by 91 general practitioners), 44.8% male and 55.2% female, with a mean +/- SD age of 62.2 +/- 6.7 years. Of these, 1977 (78.4%) had at least one of the recognized cardiovascular risk factors (arterial hypertension, hypercholesterolaemia, obesity, a family history of myocardial infarction, diabetes mellitus). Half of the study population had two or more risk factors, and one-third had a single one. On the assumption that vitamin E and aspirin are an attractive basis for a clinical trial of primary prevention strategies, we evaluated the fraction of the population at risk who would be suitable for recruitment. Exclusion criteria reduced this fraction to 50.2% (992 out of 1977) of eligible patients. General exclusion criteria were present in 501 (25.3%), indications for aspirin in 428 (21.6%) and contraindications to aspirin in 526 patients (26.6%). Because no contraindications to vitamin E are known, three-quarters of the exclusion criteria used applied to aspirin treatment only; this implies that a larger fraction of the population at risk would be suitable for testing the efficacy of vitamin E or other preventive strategies.

CONCLUSION: The large proportion of candidates for cardiovascular prevention within the general population (992 out of 2522, 39.3%) and the reliability of the general practitioners' participation in the study supported the feasibility of clinical tests of preventive strategies in primary health care.