Assessing the psychometric properties of generic (EQ-5D-5L) and disease-specific (KCCQ) quality of life in patients with hypertrophic cardiomyopathy in the AFFECT-HCM study.

Background: To assess the psychometric properties (content validity, reliability and construct validity) of generic and disease-specific health-related quality of life (HRQoL) instruments in patients with hypertrophic cardiomyopathy (HCM) and genotype-positive, phenotype-negative (G+/P-) individuals.

Methods: As part of the multicentre, observational AFFECT-HCM study, HRQoL was measured using the generic EuroQoL-5 Dimension-5 Level (EQ-5D-5L) questionnaire, the Visual Analogue Scale (EQ VAS) and the disease-specific Kansas City Cardiomyopathy Questionnaire (KCCQ). The study included G+/P- individuals and HCM patients. EQ-5D-5L profiles were translated into EQ-5D values (utilities) using the Dutch value set. All instruments were evaluated regarding their general characteristics and health dimensions (content validity). Reliability was assessed using internal consistency (Cronbach's alpha), response rate, floor/ceiling effects (percentage scoring highest/lowest), correlation and level of agreement between instruments (using Bland-Altman plots). Construct validity was assessed using the known-groups method to identify expected differences between relevant groups.

Results: A total of 393 HCM patients and 78 G+/P- individuals were included in the psychometric assessment. Mean EQ-5D value in G+/P- individuals was 0.90 (81 EQ VAS, 93 KCCQ) and in HCM patients 0.84 (75 EQ VAS, 78 KCCQ). Ceiling effects were highest for EQ-5D values (51% in G+P; 32% in HCM), followed by the KCCQ (38% in G+P-; 12% in HCM) and the EQ VAS (8% in G+P-; 5% in HCM). KCCQ and EQ-5D values had the highest correlation (Spearman's ρ=0.77) and showed good overall agreement according to the Bland-Altman plots. In HCM, EQ-5D values showed a slightly biased pattern with EQ-5D values scoring higher than the KCCQ. The KCCQ discriminated more nuances between relevant groups.

Conclusions: Due to its simplicity and good overall agreement with the KCCQ-which showed slightly better discrimination-we propose from our data that the EQ-5D-5L is a suitable instrument for the HRQoL assessment in clinical practice in patients with HCM.