The validity of the Finnish Hospital Discharge Register and Causes of Death Register data on coronary heart disease

Abstract

BACKGROUND AND DESIGN: The recent introduction of sensitive markers of myocardial injury is likely to affect the epidemiology of coronary heart disease (CHD). The American Heart Association together with other societies and research agencies have recently published a new definition on acute CHD to improve consistency in epidemiological and clinical studies (referred here as the '2003 definition'). METHODS: In this study we compare the data on CHD events in the Finnish National Hospital Discharge Register (HDR) and the Causes of Death Register (CDR) with the population-based myocardial infarction (MI) register, FINMONICA/FINAMI. The FINMONICA/FINAMI events were classified according to the 2003 definition. The relevant International Classification of Diseases (ICD) codes from the HDR and CDR were used. RESULTS: Using the 2003 definition as the reference, the overall sensitivity of the ICD codes for MI in the combined HDR and CDR was 83% and the positive predictive value (PPV) was 90%. When the ICD codes for unstable angina were added to the analyses, the sensitivity improved to 85% and the PPV declined to 83%. In the age group 35-74 the sensitivity of the MI codes improved over time, in men from 64% in 1988-1992 to 81% in 1998-2002, and in women from 61 to 78%, respectively. The oldest age group, 75 years or older, had sensitivity and PPV values comparable to those of the younger. CONCLUSION: Diagnoses of fatal and non-fatal CHD events in the Finnish HDR and Causes of Death register were reasonably valid indicators for hard CHD events when compared with the FINMONICA/FINAMI register data.