Quality of life assessment in patients with heart failure: validity of the German version of the generic EQ-5D-5L™

Background Chronic heart failure patients typically suffer from tremendous strain and are managed mainly in primary care. New care concepts adapted to the severity of heart failure are a challenge and need to consider health-related quality of life aspects. This is the first psychometric validation of the German EQ-5D-5L (TM) as a generic instrument for assessing health-related quality of life (HRQOL) in a primary care heart failure patient sample. Methods Confirmatory factor analysis (CFA) was performed on the baseline EQ-5D-5L (TM) data from the RECODE-HF study (responses to all items from n = 3225 of 3778 patients). Basic CFA models for HRQOL were calculated based on the EQ-5D-5L (TM) items using the maximum likelihood (ML) and the asymptotic distribution-free method. In an extended CFA, physical activity and depression were added. The basic CFA ML model was verified for the reduced number of cases of the extended CFA model (n = 3064). In analyses of variance the association of the EQ-5D-5L (TM) visual analogue scale (VAS) and both the German and the British EQ-5D-5L (TM) crosswalk index with the SF-36 measure of general health were examined. The discriminant validity was analysed using Pearson's chi-squared tests applying the New York Heart Association classification, for the VAS and indices analyses of variance were calculated. Results In the basic CFA models the root mean square error of approximation was 0.095 with the ML method, and 0.081 with the asymptotic distribution-free method (Comparative Fit Index > 0.90 for both). Physical activity and depression were confirmed as influential factors in the extended model. The VAS and indices were strongly associated with the SF-36 measure of general health (partial eta-squared 0.525/0.454/0.481; all p < 0.001; n = 3155/3210/3210, respectively), also for physical activity and depression when included together (partial eta-squared 0.050, 0.200/0.047, 0.213/0.051 and 0.270; all p < 0.001; n = 3015/n = 3064/n = 3064, respectively). The discriminant validity analyses showed p-values < 0.001 and small to moderate effect sizes for all EQ-5D-5L (TM) items. Analyses of variance demonstrated moderate effect sizes for the VAS and indices (0.067/0.087/0.084; all p < 0.001; n = 3110/3171/3171). Conclusion The German EQ-5D-5L (TM) is a suitable method for assessing HRQOL in heart failure patients.