First myocardial infarction in a Dutch general practice population: trends in incidence from 1975-2003.

Background: As morbidity registrations generally do not make distinct first and following myocardial infarctions, it is still unclear as to what extent the falling rates of myocardial infarctions are caused by lower incidences of first myocardial infarctions.

Aim: To investigate the incidence of first myocardial infarctions in a general practice population.

Method: Data were taken from the Continuous Morbidity Registration (CMR) Nijmegen, which has been collecting data from four general practices since 1971. For the 1975-2003 period, sex-specific and age-specific yearly incidence rates were obtained from the registration data of the CMR. Trends were studied with Poisson regression.

Results: During the study period, 827 patients with a first myocardial infarction were identified. The incidence of first myocardial infarctions has declined since 1986 to 2.1 per 1000 for men and to 1.5 per 1000 for women. The average age of getting a first myocardial infarction increased with 3 years for men and slightly decreased for women. Since 1986, the incidence of sudden cardiac death from a first myocardial infarction has considerably declined for men and women to 0.9 and 0.7 per 1000 respectively.

Conclusion: A slight, significant, decline in incidence of first myocardial infarctions was found. From the mid eighties a mean annual decline of 3.5% in death from first myocardial infarction was observed. Though the variance in rates of coronary heart diseases is not unambiguous, this may indicate an effect of primary prevention. The decline was more pronounced in men, with an increasing age of getting a first myocardial infarction.