Position matters: Validation of medicare hospital claims for myocardial infarction against medical record review in the atherosclerosis risk in communities study.

PURPOSE: The objectives of this study were to investigate sensitivity and specificity of myocardial infarction (MI) case definitions using multiple discharge code positions and multiple diagnosis codes when comparing administrative data to hospital surveillance data.
METHODS: Hospital surveillance data for ARIC Study cohort participants with matching participant ID and service dates to Centers for Medicare and Medicaid Services (CMS) hospitalization records for hospitalizations occurring between 2001 and 2013 were included in this study. Classification of Definite or Probable MI from ARIC medical record review defined "gold standard" comparison for validation measures. In primary analyses, an MI was defined with ICD9 code 410 from CMS records. Secondary analyses defined MI using code 410 in combination with additional codes.
RESULTS: A total of 25 549 hospitalization records met study criteria. In primary analysis, specificity was at least 0.98 for all CMS definitions by discharge code position. Sensitivity ranged from 0.48 for primary position only to 0.63 when definition included any discharge code position. The sensitivity of definitions including codes 410 and 411.1 were higher than sensitivity observed when using code 410 alone. Specificity of these alternate definitions was higher for women (0.98) than for men (0.96).
CONCLUSION: Algorithms that rely exclusively on primary discharge code position will miss approximately 50% of all MI cases due to low sensitivity of this definition. We recommend defining MI by code 410 in any of first 5 discharge code positions overall and by codes 410 and 411.1 in any of first 3 positions for sensitivity analyses of women.