WHO Disability Assessment Schedule 2.0: responsiveness in detecting long-term functional disability after surgery

Abstract Background The WHO Disability Assessment Schedule (WHODAS) 2.0 is widely used for detecting postoperative functional disability. Its responsiveness for detecting disability has been evaluated at 1 year after surgery, with no long-term evaluation. The aim of this study was to examine the responsiveness of the WHO Disability Assessment Schedule in detecting functional disability at 5 years after surgery. Methods This study was a secondary analysis of a prospective observational study. Patients were enrolled who were aged 55 years or older and underwent elective non-cardiac surgery under general anaesthesia. They were asked to complete the 12-item WHO Disability Assessment Schedule and the Medical Outcome Study Short Form questionnaires before surgery and at 5 years after surgery. The correlation between changes in WHO Disability Assessment Schedule score and Medical Outcome Study Short Form physical score (change in physical component score) was evaluated using the Spearman rank correlation coefficient (ρ). The standardized response means were also calculated for typical subgroups for which functional disability was predicted to improve or decline and compared with the overall standardized response mean. Results In the analysis, 2596 patients were included. A moderate correlation (ρ = −0.47) existed between changes in WHO Disability Assessment Schedule and physical Medical Outcome Study Short Form scores. The overall standardized response mean was 0.17. The standardized response means for the patients with functional disability predicted to improve ranged from −0.45 to −0.67, whereas those for patients predicted to decline ranged from 0.17 to 0.56. These findings indicated high responsiveness. Conclusion The WHO Disability Assessment Schedule 2.0 has a high responsiveness at 5 years after surgery. It can be used to detect functional disability at 5 years after surgery.