Association of baseline physical activity participation with participant characteristics and outcomes following education and exercise-therapy in people with knee osteoarthritis: A GLA:D® Australia prospective cohort study

Objectives: To investigate whether participants with knee osteoarthritis classified as ‘more’ or ‘less’ physically active at baseline differ in characteristics and/or outcomes at baseline and at 3 and 12 months following the commencement of an education and exercise-therapy program. Methods: Prospective cohort study using the GLA:D® Australia registry. The University of California, Los Angeles Physical Activity Scale (UCLA) participant data dichotomised as ‘more’ (≥7) or ‘less’ active (≤6). Groups were compared using chi-square (obesity [baseline only], comorbidity prevalence, medication consumption, fear of damage from physical activity); and linear mixed model regression (12-item Injury Osteoarthritis Outcome Score [KOOS-12], pain [visual analogue scale], health-related quality of life [QoL] [EQ-5D-5L]) statistics, adjusted for age, sex and baseline physical activity at 3 and 12 months. Results: We included 1059 participants (70% female). At baseline, 267 (25%) were classified as ‘more’ active, increasing to 29% and 30% at 3 and 12 months, respectively. At baseline, compared to the ‘less’ active group, the ‘more’ active group had a lower proportion of participants who were obese (‘more’ = 21% vs. ‘less’ = 44%), had comorbidities (58% vs. 74%) and consumed medications (71% vs. 85%); lower pain intensity (37 vs. 47); and higher KOOS-12 (59 vs. 50), and health-related QoL (0.738 vs. 0.665) scores. When accounting for age, sex and baseline physical activity, improvements seen in knee-related burden and health-related QoL were not different between groups at 3 or 12 months. Compared to the ‘less’ active group, the proportion of participants not consuming medication remained higher in the ‘more’ active group at 3 (‘more’ 45% vs. ‘less’ 28%) and 12 months (43% vs. 32%). Conclusion: ‘More’ active people with knee osteoarthritis were less likely to be obese, had fewer comorbidities, lower medication consumption, knee-related burden and pain intensity, and higher health-related QoL than ‘less’ active participants at all timepoints.