Feasibility, reliability, and validity of the Japanese version of the 12-item World Health Organization Disability Assessment Schedule-2 in preoperative patients

The avoidance of postoperative functional disability is one of the most important concerns of patients facing surgery, but methods to evaluate disability have not been definitively established. The aim of our study was to evaluate the feasibility, reliability, and validity of the Japanese version of the 12-item World Health Organization Disability Assessment Schedule-2 (WHODAS 2.0-J) in preoperative patients. Individuals aged >= 55 years who were scheduled to undergo surgery in a tertiary-care hospital in Japan between April 2016 and September 2016 were eligible for enrolment in the study. All patients were assessed preoperatively using the WHODAS 2.0-J, the 8-Item Short Form (SF-8) questionnaire, and the Tokyo Metropolitan Institute of Gerontology Index (TMIG Index). The feasibility, reliability, and validity of WHODAS2.0-J were evaluated using response rate, Cronbach's alpha (a measure of reliability), and the correlation between the WHODAS 2.0-J and the SF-8 questionnaire and TMIG Index, respectively. A total of 934 patients were enrolled in the study during the study period, of whom 930 completed the WHODAS 2.0-J (response rate 99.5%) preoperatively. Reliability and validity were assessed in the 898 patients who completed all three assessment tools (WHODAS 2.0-J, SF-8 questionnaire, and TMIG Index) and for whom all demographic data were available. Cronbach's alpha was 0.92. The total score of the WHODAS 2.0-J showed a mild or moderate correlation with the SF-8 questionnaire and TMIG Index (r = -0.63 to -0.34). The WHODAS 2.0-J is a feasible, reliable, and valid instrument for evaluating preoperative functional disability in surgical patients.