Reliability and Validity of the Kansas City Cardiomyopathy Questionnaire in Patients with Previous Myocardial Infarction

BACKGROUND: The Kansas City Cardiomyopathy Questionnaire (KCCQ) is a recently developed disease-specific instrument for measuring health-related quality of life (HRQoL) in patients with chronic heart failure (CHF) regardless of aetiology. AIM: To assess the reliability and validity of the KCCQ in patients with previous myocardial infarction (MI). METHODS AND RESULTS: In 754 myocardial infarction patients who were discharged alive, we collected clinical data from the patients' medical records. Two and a half years after the acute myocardial infarction, we mailed a self-administered questionnaire to the 548 patients still alive. The response rate was 74%. Internal consistency reliability, assessed with Cronbach's alpha, ranged 0.66-0.95. Test-retest reliability, tested with an intraclass correlation coefficient (ICC), ranged 0.41-0.83. The pattern of association between similar and dissimilar scales of the KCCQ and Short Form 36 (SF-36) supported the convergent/divergent validity of the KCCQ. Four of the KCCQ scales and the two summary scores discriminated between patients with and without medication for heart failure, and between different levels of left ventricular ejection fraction (LVEF) supporting different groups validity. CONCLUSIONS: The Norwegian version of the KCCQ showed acceptable reliability and cross-sectional validity, which support the use of this questionnaire to measure health-related quality of life after myocardial infarction.