Benefits of a transtheoretical model-based program on exercise adherence in older adults with knee osteoarthritis: A cluster randomized controlled trial

Aims: Benefits of a transtheoretical model-based exercise program on exercise adherence (primary outcome) and secondary outcomes (self-efficacy, decisional balance, knee osteoarthritis symptoms, and physical function) were assessed among older adults with knee osteoarthritis. Design: A two-arm, superiority, assessor-blinded, cluster randomized trial with randomization at the community level. Methods: Participants were recruited from 14 communities in Beijing between April - October 2018 (N = 189). The intervention was a 24-week transtheoretical model-based exercise program and the control group underwent a non-theory–based exercise program. Exercise adherence was collected every 4 weeks and secondary outcomes were measured at baseline, 12 weeks, and 24 weeks. An independent t test and repeated-measures ANOVA were the main statistical tests. Results: Most participants were women (92.5%), married (81.4%), with high-school education (36.0%), with both knees affected (50.3%), and did not make use of a walker (93.8%). There were no significant differences between groups in any of the outcome measures at baseline. Repeated-measures ANOVA indicated that there was a significant difference in the trend of adherence scores between the two groups from 0–24 weeks. The independent t test showed that scores in the intervention group were significantly better than in the control group at 16, 20, and 24 weeks. Improvements in the intervention group were also significantly greater in all secondary outcomes than in the control group. Conclusion: A theory-based exercise program could improve exercise adherence, self-efficacy, decisional balance, knee osteoarthritis symptoms, and physical functioning in older adults with knee osteoarthritis. Trial registration: Chinese Clinical Trials Registry number ChiCTR1800015458. Registered 31 March 2018. Impact: The 24-week theory-based exercise program could improve exercise adherence, self-efficacy, decisional balance, symptoms of knee osteoarthritis, and physical functioning in older adults with knee osteoarthritis. The theory-based exercise program could help older adults with knee osteoarthritis to improve their symptoms and knee function.