Psychometric properties of the German version of the MacNew heart disease health-related quality of life questionnaire

BACKGROUND Assessment of health-related quality of life, increasingly being used as an outcome measure in cardiovascular disease research studies and clinical practice, requires questionnaires with sound psychometric properties. The aim of this study was to evaluate the psychometric properties of the Flemish version of the MacNew Heart Disease Health-related Quality of Life questionnaire in Flemish-speaking Belgian patients. METHOD Between 2002 and 2008, as part of the international HeartQol Project, 344 Belgian patients with a diagnosis of angina, ischaemic heart failure or myocardial infarction completed the Flemish versions of the MacNew, the Short-Form 36 and the Hospital Anxiety and Depression Scale. Ceiling and floor effects of the MacNew were analysed. Internal consistency was assessed by Cronbach's a and reproducibility (intra-class correlation coefficients) was assessed in a subsample of patients over a 2-3 week period with repeated tests. Convergent validity (Pearson's correlation between MacNew and Short-Form 36 constructs) and discriminant validity ('known-group' approach) were tested. RESULTS The Flemish version of the MacNew appears to be a reliable instrument with a high internal consistency, demonstrating strong discriminative validity and satisfactory construct validity. The results of factor analysis are similar to the factor structure of the original MacNew explaining 59.8% of the total variance. CONCLUSION The Flemish version of the MacNew demonstrates good psychometric properties. It can be recommended as a specific instrument for assessing and evaluating health-related quality of life in Flemish-speaking patients in each of the three major ischaemic heart disease diagnoses: angina, ischaemic heart failure and myocardial infarction. However, responsiveness to change could not be tested in this cross-sectional study and should be further investigated in a larger sample of patients following an intervention likely to induce a change in health-related quality of life.