A comparison of psychological characteristics in people with knee osteoarthritis from Japan and Australia: A cross-sectional study.

The aim of this study was to investigate differences in psychological characteristics between people with knee osteoarthritis (OA) from Japan and Australia. Sixty-two adults from Japan and 168 adults from Australia aged over 50 years with knee pain were included. Japanese data were collected from patients with knee OA diagnosed by medical doctors. Australian data were baseline data from a randomized controlled trial. Participants were not exercising regularly or receiving physiotherapy at the time. Psychological characteristics evaluated were depressive symptoms, fear of movement, and pain catastrophizing. These psychological characteristics were compared between the Japanese and Australian cohorts by calculating 95% confidence intervals (CIs) for difference of the mean. To test for equivalence, an equivalence margin was set at 0.5 standard deviations (SD) of the mean, where these SDs were based on the Australian data. When the 95%CI for the difference of the mean value lay entirely within the range of equivalence margin (i.e. between -0.5 and 0.5 times the Australian SD), the outcome was considered equivalent. There were no differences between the groups from Japan and Australia for depressive symptoms and the two groups were considered equivalent. There was no difference between groups for fear of movement, however the criteria for equivalence was not met. People from Japan with knee OA had higher scores for pain catastrophizing than people from Australia. The findings should be confirmed in other samples of people with knee OA from Japan and Australia due to the limitations of the participant recruitment strategy in this study. However, our findings suggest there may be a greater need to consider pain catastrophizing and build pain self-efficacy when managing Japanese people with knee OA. Implementation of international clinical practice guidelines for OA management may require different strategies in different countries due to different psychological profiles.