Misclassification and under-reporting of acute myocardial infarction by elderly persons: implications for community-based observational studies and clinical trials.

We investigated the accuracy of self-report of hospitalization for acute myocardial infarction (MI) by elderly persons in a community-based prospective study. Among 3809 persons aged 65 years or older followed up for 6 years, self-reported hospitalization for MI was validated by review of primary records and Medicare diagnoses. Among 147 who self-reported MI and for whom hospital records were available, the diagnosis was confirmed in 79 (54%). Myocardial infarction was not a reason for hospitalization among the remaining 68 participants; misclassification with other cardiovascular diagnoses was common. Medicare diagnosis correlated well with primary hospital records. Using Medicare diagnoses as the standard, the diagnosis of MI was confirmed in 53% of self-reports; the sensitivity and specificity of self-report were 51% and 98%, respectively. False-negative reporting was common because only half of hospitalizations for MI were reported. Self-report of hospitalization for MI by elderly persons in the community may be unreliable for ascertaining trends in cardiovascular diseases.