Association between psychological factors and physical performance in individuals with knee osteoarthritis: A cross-sectional study

Background: The association between psychological factors and physical performance is still unclear, as pain may also be associated with psychological factors and self-reported and objective physical performance. Organizing the variables for pain intensity, symptoms of depression, and pain catastrophizing hierarchically could aid in clarifying this association. Objective: To investigate whether there is an association between different pain measures, psychological factors, and poor physical performance in individuals with knee osteoarthritis (KOA) by considering the influence of age and body mass index. Methods: Ninety-eight individuals with KOA participated in this cross-sectional study between May 2018 and October 2019. The main assessment measures included the Numerical Pain Scale, Pressure Pain Threshold, Beck Depression Inventory, Pain Catastrophizing Scale, Western Ontario and McMaster Universities Osteoarthritis Questionnaire (WOMAC), and gait speed. The multiple linear regression F-tests were used for statistical analysis. Results: Different regression models revealed that the Pain subscale of WOMAC for pain intensity was the variable most strongly associated with low self-reported [F(3,94)=65.440; p < 0.001; R-2 = 0.676] and objective physical performance [ F(3,94) = 4.827; p=0.004; R-2=0.141]. Furthermore, pain catastrophizing was the psychological factor most strongly associated with low self-reported physical performance [F(4,92)=21.531; p < 0.001; R-2=0.484], while depressive symptoms were the psychological factor most strongly associated with low objective physical performance [F(3,87)=8.909; p < 0.001; R-2=0.235]. Conclusion: This study identified that pain catastrophizing and depressive symptoms are the strongest predictors of low self-reported and objective physical performance, respectively. These findings suggest that the appropriate use of those tools can enhance clinical assessment and psychosocial approach.