The feasibility of routine mortality and morbidity register data linkage to study the occurrence of acute coronary heart disease events in Finland - The Finnish Cardiovascular Diseases Registers (CVDR) Project

Validated population-based data on the occurrence of coronary heart disease in Finland have previously been obtained from myocardial infarction (MI) r egisters. Such registers cannot, however, cover large areas. Therefore, the Finnish Cardiovascular Diseases Registers (CVDR) Project was set up to obt ain data for the whole of Finland. The CVDR Project is based on routine mor tality and morbidity data linkage. We report here the overall approach used in the project, the results of the feasibility study and the first main re sults. In Finland, data on all hospitalizations are registered in the natio nwide Hospital Discharge Register. Also, data on all deaths are collected i n the nationwide Causes of Death Register. The unique personal identificati on number assigned to all persons residing in Finland was used for data lin kage. Data have been validated using the FINMONICA MI registers. Sensitivit y analyses showed that the data were robust and consistent between differen t geographical areas. Coronary heart disease (CHD) mortality as well as the incidence and event rates showed the same very clear geographical pattern, dividing Finland to a southwest area with a lower occurrence and a northea st area with nearly twice higher occurrence. Case fatality did not differ m uch between the areas and did not follow this Southwest-Northeast division. The differences between northeast and southwest Finland may be related to differences in risk factor levels but also to socioeconomic and genetic dif ferences. The CVDR Project data will be instrumental in further research ad dressing these issues.