Rasch Model Analysis of the Indonesian Version of World Health Organization Disability Assessment Schedule (WHODAS 2.0)

Abstract

Background & Aims: This study evaluated the construct validity of the Indonesian version of WHODAS 2.0 among persons with physical impairment. Methods: WHODAS 2.0 was self-administered to 212 participants with physical impairment in Bandung, Indonesia. The Rasch model was used to analyse the instrument ’ s construct validity. Results: Data of 212 participants were analysed. The average outfit mean-square ( MnSq ) of the 36-item and 32-item versions of WHODAS 2.0 satisfied the Rasch model expectations (0.99 ± 0.28 vs 0.99 ± 0.24). Item D2.5 ‘ walking a long distance such as a kilometre ’ and item D4.5 ‘ sexual activity ’ were identified as misfitting items in both versions ( infit or outfit MnSq ＞ 1.4 ) . The variance explained by measures of the 32 - item version was 56.7 ％ , and the 36 - item version was 49.0 ％ . Both versions ’ reliability and separation index were excellent, with Cronbach ’ s alpha ＞ 0.90 and a separation index ＞ 2 . The response category function and targeting did not fully satisfy the Rasch model expectations. A strong correlation between both versions of WHODAS 2.0 and WHOQOL BREF (r ＞ 0.60) established the convergent validity. Conclusions: The Indonesian version of the 32-item version of WHODAS 2.0 has acceptable construct validity in a physical impairment sample in Bandung, Indonesia.