Estimating the incidence of the acute coronary syndrome: data from a Danish cohort of 138 290 persons.

Background: Estimates of incidence are crucial to the planning of public health measures, but most studies of incidence of, for example, acute myocardial infarction (MI) are troubled by methodological problems such as; (i) selection biases of the patients being included for study, (ii) lack of identification and control of the cohort under observation, (iii) inconsistencies in the use of diagnostic criteria, and (iv) missing data. We aimed to measure directly the incidence of the entire spectrum of the acute coronary syndrome (ACS), consisting of unstable angina pectoris, MI and sudden cardiac death (SCD), by use of the new criteria for MI as proposed in 2000.

Design: Cohort study.

Methods: From a cohort of 138 290 residents of the municipality of Aarhus, Denmark, aged 30-69 years, with a demographic structure known at the individual population member level, we prospectively identified all consecutive ACS patients from 1 April 2000 to 31 March 2002. The population was identified from Danish Population Registers.

Results: A total of 189 victims of SCD and 457 ACS patients who survived until admission to hospital were present. Consequently, crude incidence rate of ACS was 234 per 100 000 person-years. Unstable angina pectoris constituted for 16.9%, MI for 53.8% and SCD for 29.3% of ACS patients.

Conclusions: Crude incidence rates of ACS were 137 and 331 per 100 000 person years for women and men, respectively. The incidence rate of ACS, as measured directly, was insignificantly 6% higher than expected from Danish administrative databases.