Evaluation of measurement properties of the Health Assessment Questionnaire-Disability Index (HAQ-DI) among gout patients in China.

OBJECTIVES: To evaluate measurement properties of Chinese version of the Health Assessment Questionnaire Disability Index (HAQ-DI) among Chinese gout patients. METHOD: A representative sample of Chinese gout patients were recruited with stratification based on age, sex, urban/rural residence, and education level. Ceiling and floor effects were evaluated. Reliability was assessed by internal consistency (Cronbach’s α). Structural validity was verified by confirmatory factor analysis (CFA). Convergent validity was assessed using Spearman’s rank coefficient, examining the correlation between the HAQ-DI and EQ-5D-5L. Known-groups validity was evaluated by determining the HAQ-DI score differences between subgroup patients. Effect sizes were then used to assess sensitivity of the subgroup differences. RESULTS: A total of 1,000 patients were included in the study. Ceiling and floor effects were both not observed. Cronbach’s α was 0.95. The factor loadings of CFA were all above 0.6 and the model fit indices were acceptable (χ2/df = 5.97, RMSEA = 0.071, RFI = 0.906, CFI = 0.940, TLI = 0.920), indicating that the eight-factor model had well structural validity. The HAQ-DI correlated in predictable ways with five EQ-5D-5L dimensions, with Spearman’s rank coefficient ranging from 0.30 to 0.61. The HAQ-DI can discriminate between subgroup patients with different levels of health status, with the mean effect size (0.73) at a medium level. CONCLUSIONS: Chinese version of the HAQ-DI was verified to have satisfactory reliability, validity, and sensitivity in measuring health-related quality of life of Chinese gout patients. We recommend supplementing the responsiveness of the HAQ-DI to changes over time in future research.