The WHO Disability Assessment Schedule 2.0 (WHODAS 2.0)-36 items

To evaluate the criterion validity of the Chinese version of the PaArticular Scales, we used the Chinese version of the WHODAS 2.0–36 items. Participants used a 5-point Likert scale to answer questions related to difficulties in performing activities. The score ranged from 0 (least difficulty) to 100 (maximum difficulty) and was calculated as the sum of each domain score [29]. A higher score indicated a higher degree of disability and more severe restriction. Restriction severity refers to the difficulty level classification method of the ICF and WHODAS 2.0. The classification of impairment severity was as follows: below 4 %, none; 5–24 %, mild; 25–49 %, moderate; 50–95 %, severe; and more than 96 %, extremely severe [30]. Four items in the WHODAS 2.0 cover job domains (e.g., Have you ever had to accept a lower-level job because of health factors?); thus, only 32 items were calculated in the study because all participants were retired and unemployed.

Regarding the reliability indices of the Chinese version of the WHODAS 2.0, Cronbach’s α for internal consistency is between 0.70 and 0.99, and the intraclass correlation coefficient is between 0.80 and 0.89 [31, 32]. Among the validity indices, the content and the concurrent validity have some correlation, and based on exploratory factor analyses (EFAs), 5 to 7 factors have an explanatory power higher than 55 %. The factor loadings of the CFA are all higher than 0.56 [31]. Therefore, the Chinese version of the WHODAS 2.0 has excellent reliability and validity and is consistent with item response theory. In the current study, authorities have granted permission for the use of each Chinese version of the survey instrument .