Association between psychological factors related to pain and instrumental activities of daily living disability in older adults with knee osteoarthritis

ObjectiveTo investigate the association between psychological factors related to pain and instrumental activities of daily living (IADL) disability in older adults with knee osteoarthritis (OA). DesignA cross-sectional study. SettingOutpatients at a general hospital in Japan. ParticipantsOne hundred seventy-nine (N=179) patients with knee OA and aged[≥]65years. InterventionsNot applicable. Main Outcome MeasureSix-item short form of the pain catastrophizing scale (PCS-6) and four-item short form of the pain self-efficacy questionnaire (PSEQ-4) were used to assess the psychological status related to pain. IADL status was assessed using eight activity items. Participants selected "able," "need help," or "unable" depending on their abilities to perform these IADL activities. If they chose "need help" or "unable" to perform, for at least one item, we defined them as "disabled." ResultsOf all participants, 88 (49.1%) showed disability in conducting IADL. Binary logistic regression analysis with the dependent variable as IADL disabled or not and PCS-6 and PSEQ-4 as independent variables were performed. Age, sex, pain intensity, depressive symptoms, usual gait speed (UGS), and isometric knee extension strength were included as covariates in the logistic regression model. Only PSEQ-4 (odds ratio [OR]=0.90, 95% confidence interval [95%CI]=0.82-0.99, p=0.02) was a significant independent variable for psychological factors related to pain. PCS-6 was not a significant variable (OR=1.06, 95%CI=0.94-1.19, p=0.13). Sex (OR=0.38, 95%CI=0.15-0.96, p=0.04) and UGS (OR=0.13, 95%CI=0.02-0.72, p=0.02) were significantly independent variables. ConclusionOur study showed the importance of assessing self-efficacy related to pain using the PSEQ-4 to determine the presence of IADL disability in older adults with knee OA.