Physical activity-adjusted pain measures may be associated with the severity of radiographic knee osteoarthritis (OA) and may be helpful for the assessment of functional capacity in these patients, according to a study published in Clinical Rheumatology.
A total of 122 veterans (mean age, 61.2 years; 88.5% men) with knee OA who were enrolled in a randomized controlled trial were included in this study. In this study, the efficacy on knee OA of group vs individual physical therapy was examined. Baseline Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scores data were adjusted for accelerometer-derived daily energy expenditure, step counts, minutes of light intensity activity, minutes of moderate or greater intensity activity, and minutes of any activity. Associations between unadjusted and physical activity-adjusted WOMAC pain scores and the 6-minute walk distance, 8-foot walk test, chair stand test, and satisfaction with physical function, as well as with fatigue (Brief Fatigue Inventory) and anxiety/depressive symptoms, were examined.
Adjusted WOMAC step count scores had stronger associations with the 4 function-related assessments (6-minute walk distance, partial Spearman correlation factor, r=−0.32; 95% CI, −0.47 to −0.14; P <.01; 8-foot walk test, r=0.42; 95% CI, 0.26-0.56; P <.01; chair stand test, r=0.36; 95% CI, 0.19-0.51; P <.01; and satisfaction with physical function, r=−0.26; 95% CI, −0.42 to −0.14; P <.01) compared with the unadjusted WOMAC pain score (partial rs=0.19–0.25). In addition, the unadjusted WOMAC pain score held stronger positive correlations with the most physical activity-adjusted pain scores for anxiety/depression (r=0.31; 95% CI, 0.13-0.46; P <.01) and fatigue (r=0.25; 95% CI, 0.07-0.42; P <.01).
Study limitations include the predominantly male cohort, the small sample size, and the recruitment of patients from a single center.
“These results suggest that in clinical OA studies, the most appropriate or sensitive symptom measure (pain vs. [physical activity]-adjusted pain) may depend on the type of intervention or outcome,” noted the study authors.
Allen KD, Lo G, Abbate LM, et al. Composite measures of physical activity and pain associate better with functional assessments than pain alone in knee osteoarthritis [published online March 30, 2019]. Clin Rheumatol. doi:10.1007/s10067-019-04530-4