Hospital discharge register data in the assessment of trends in acute myocardial infarction. FINMONICA AMI Register Study Team.

We evaluated the reliability hospital discharge register data in the assessment of acute myocardial infarction trends. In the FINMONICA study areas, trends in age standarized attack rates for the years 1983-90 were calculated independently from two sources: the nationwide Finnish hospital discharge register and the FINMONICA acute myocardial infarction register. The trends were compared by a statistical regression model. The trends obtained from the hospital discharge register were very similar to the trends obtained from the FINMONICA acute myocardial infarction register. The attack rates differed significantly, however, and the change in the International Classification of Diseases version from version 8 to version 9 brought on a change in the attack rates obtained from the hospital discharge register. Thus, hospital discharge register data can be used to assess acute myocardial infarction trends in the community. However, modifications of the International Classification of Diseases codes (new versions of the classification) and changes in the clinical use of the codes for coronary heart disease can have an impact on the attack rates obtained from the hospital discharge register, and the reliability of the hospital discharge register data should be regularly assessed.