Trends in the Sensitivity, Positive Predictive Value, False-Positive Rate, and Comparability Ratio of Hospital Discharge Diagnosis Codes for Acute Myocardial Infarction in Four US Communities, 1987-2000

Variations in the validity of hospital discharge diagnoses can complicate the assessment of trends in incidence of acute myocardial infarction (AMI). To clarify trends in the validity of discharge codes, the authors compared event classification based on published Atherosclerosis Risk in Communities (ARIC) Study criteria with the presence or absence of an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) hospital discharge code for AMI (code 410). Between 1987 and 2000, 154,836 coronary heart disease events involving hospitalization in the four ARIC communities had ICD-9-CM codes screened for AMI. The sensitivity of ICD-9-CM code 410 for classifying AMI in men (sensitivity = 0.65, 95% confidence interval (CI): 0.63, 0.66) was statistically significantly greater than that found for women (sensitivity = 0.60, 95% CI: 0.58, 0.62) and was greater in Whites (sensitivity = 0.67, 95% CI: 0.65, 0.68) than in Blacks (sensitivity = 0.50, 95% CI: 0.47, 0.53). The ethnic difference was related to a greater frequency of hypertensive heart disease and congestive heart failure codes encompassing AMI among Blacks as compared with Whites. The authors found that although the validity of ICD-9-CM code 410 to identify AMI was generally stable from 1987 through 2000, differences between Blacks and Whites and across geographic locations support investment in validation efforts in ongoing surveillance studies.