Abstract
PURPOSE: The aim of this study was to evaluate psychometric properties of the core disease-specific 14-item German HeartQoL questionnaire. METHODS: As an extension of the international HeartQol Project, cross-sectional and longitudinal health-related quality of life (HRQL) data were collected from 305 patients with angina (N = 101), myocardial infarction (N = 123), or ischemic heart failure (N = 81) in Austria and Switzerland using German versions of the HeartQoL, the Short Form-36 Health Survey (SF-36), and the Hospital Anxiety and Depression Scale. The underlying factor structure was examined with Mokken Scaling analysis; then convergent, divergent, and discriminative validity, internal consistency reliability, and responsiveness were assessed. RESULTS: The highest HRQL scores were reported by patients with myocardial infarction followed by ischemic heart failure and then angina. The two-factor structure was confirmed with strong physical, emotional, and global scale H coefficients (> .50). Divergent and convergent validity (from r = .04 to .78) were shown for each diagnosis; discriminative validity was verified as well (partially: age, sex, and disease severity; largely: SF-36 health status/transition; totally: anxiety and depression). Internal consistency reliability was excellent (Cronbach's alpha = .91). In terms of responsiveness, physical and global scale scores improved significantly after percutaneous coronary intervention (p < .01) while after cardiac rehabilitation all scale scores improved significantly (p < .001). CONCLUSIONS: The German HeartQoL questionnaire is a valid and reliable HRQL instrument with these data supporting its potential use in clinical practice and research to assess and compare HRQL in German-speaking patients with ischemic heart disease. The shortness of the tool may prove to be helpful particularly in clinical practice.