Validity and measurement equivalence of EQ-5D-5L questionnaire among heart failure patients in Malaysia: a cohort study.

ABSTRACT

AIM: This study aimed to examine the validity of EQ-5D-5L among HFrEF patients in Malaysia, and to explore the measurement equivalence of three main language versions. METHODS: We surveyed HFrEF patients from two hospitals in Malaysia, using Malay, English or Chinese versions of EQ-5D-5L. EQ-5D-5L dimensional scores were converted to utility scores using the Malaysian value set. A confirmatory factor analysis longitudinal model was constructed. The utility and visual analog scale (VAS) scores were evaluated for validity (convergent, known-group, responsiveness), and measurement equivalence of the three language versions. RESULTS: 200 HFrEF patients (mean age = 61 years), predominantly male (74%) of Malay ethnicity (55%), completed the admission and discharge EQ-5D-5L questionnaire in Malay (49%), English (26%) or Chinese (25%) languages. 173 patients (86.5%) were followed up at 1-month post-discharge (1MPD). The standardized factor loadings and average variance extracted were ≥ 0.5 while composite reliability was ≥ 0.7, suggesting convergent validity. Patients with older age and higher New York Heart Association (NYHA) class reported significantly lower utility and VAS scores. The change in utility and VAS scores between admission and discharge was large, while the change between discharge and 1MPD was minimal. The minimal clinically important difference for utility and VAS scores was ±0.19 and ±11.01, respectively. Malay and English questionnaire were equivalent while the equivalence of Malay and Chinese questionnaire was inconclusive. LIMITATION: This study only sampled HFrEF patients from two teaching hospitals, thus limiting the generalizability of results to the entire heart failure population. CONCLUSION: EQ-5D-5L is a valid questionnaire to measure health-related quality of life and estimate utility values among HFrEF patients in Malaysia. The Malay and English versions of EQ-5D-5L appear equivalent for clinical and economic assessments.

EQ-5D is the most commonly used questionnaire to measure patients' health-related quality of life in clinical trials and health technology assessments. To increase confidence over clinical trial findings that heart failure interventions improve health-related quality of life and quality-adjusted life years (number of years alive with equivalence health-related quality of life), the questionnaire used to measure health-related quality of life needs to be validated in the specific population. Since EQ-5D-5L has not been validated in Malaysia's heart failure with reduced ejection fraction (HFrEF) population, this study evaluated the psychometric properties (validity) of EQ-5D-5L among HFrEF patients in Malaysia and the equivalence of different versions of languages (i.e. Malay, Chinese and English) of EQ-5D-5L in measuring the health-related quality of life. The findings suggested that EQ-5D-5L is a valid questionnaire to measure the health-related quality of life in HFrEF patients and estimate the quality-adjusted life years. The Malay and English versions of EQ-5D-5L appear to be equivalent for use in clinical trials and health technology assessments.