Validation of coronary heart disease death certificate diagnoses

Data from a coronary heart disease register in Auckland have been used to validate routine death certificate data produced by the National Health Statistics Centre. The register used current World Health Organisation criteria for definite or possible coronary heart disease and identified all suspected events in people aged less than 65 years for the years 1983 and 1984. During this period 768 coronary heart disease cases were included in the register and in the same population 772 death certificates were coded 410-414 (coronary heart disease), according to the ninth revision of the International Classification of Diseases, by the National Health Statistics Centre. Ninety one percent of deaths meeting the register's criteria for definite or possible coronary heart disease were coded 410-414 in the official data. Conversely of all death certificates coded 410-414, 93% were registered as due to coronary heart disease. The validity of subcategories was considerably lower; only 49% of deaths coded 410 (acute myocardial infarction) were categorised as definite myocardial infarction by the register. These findings suggest that the broad official statistics for the category coronary heart disease mortality (codes 410-414) are accurate to within approximately 10% in New Zealand; the validity of the subcategory myocardial infarction (code 410) is considerably lower.