Gait speed and pain status as discriminatory factors for instrumental activities of daily living disability in older adults with knee osteoarthritis

Aim: Factors related to instrumental activities of daily living disability in older adults with knee osteoarthritis are unclear. This study aimed to examine the discriminatory accuracy for the presence of instrumental activities of daily living disability in older adults with knee osteoarthritis by combining two factors of gait ability and pain status.

Methods: A cross-sectional study was conducted on 114 patients with knee osteoarthritis aged $\ge$ 65 years. Participants were divided into instrumental activities of daily living disabled or non-disabled groups. A logistic regression model was created with usual gait speed and knee injury and osteoarthritis outcome score-pain subscale as independent variables for discriminating the presence of instrumental activities of daily living disability. The area under the receiver operating characteristic curve was inspected to determine discriminatory accuracy of the logistic regression model, usual gait speed, knee injury and osteoarthritis outcome score-pain subscale.

Results: Of the 114 patients, 26 (22.8%) had instrumental activities of daily living disability. The area under the curves was 0.91 (95% confidence interval: 0.85-0.96) for the logistic regression model, 0.78 (95% confidence interval: 0.68-0.89) for usual gait speed, and 0.73 (95% confidence interval: 0.61-0.84) for knee injury and osteoarthritis outcome score-pain subscale.

Conclusions: This study showed that gait speed and pain status were independent discriminatory factors and combining these factors to discriminate more accurately the presence or absence of instrumental activities of daily living disability in older adults with knee osteoarthritis was important. Geriatr Gerontol Int 2021; 21: 683-688.