BACKGROUND: Osteoarthritis (OA) is one of the chief forms of arthritis and a major reason for disability among older adults. Weight loss is a non-pharmacologic intervention that may help decrease the effects of OA while improving one’s quality of life. The objective of the I-CAN study was to determine whether the weight-loss maintenance (WLM) intervention had a long lasting impact on self-efficacy, maintained weight loss, and ultimately better clinical outcomes. METHODS: Participants who lost more than 5% of their base body weight in the parent study (Weight Loss and Exercise for Communities with Arthritis in North Carolina), were re-randomized and placed into a WLM or an attention control (AC) group. The WLM intervention was a 6-month facilitated maintenance phase that included exercise, as well as group and individual behavioral sessions grounded in social cognitive theory to increase self-efficacy. The AC group included sessions to provide social interaction and health education. The primary outcome was weight change from baseline to the end of intervention. This treatment effect was estimated using mixed linear models adjusted for site, sex, and baseline values of the outcome. Effect sizes were estimated using Cohen’s d. Additionally, the role played by self-efficacy for maintaining weight loss on one’s own was examined. RESULTS: At the start of I-CAN, the participants (n=104, 79 females, mean age=67 years) had a weight of 85.1 kg (SD 13.9). At the 6-month follow up the WLM group gained back less weight (mean=1.3 kg; 95% CI -0.25, 2.86) compared to the control group who regained at nearly twice the rate (mean=3.5 kg; 95% CI 1.80, 5.11; P=.037). Self-efficacy accounted for 22% of the total effect of the WLM group. Interviews at the end of the intervention suggest that the WLM was well-received, with all participants endorsing the statement “The program had a positive impact on my confidence that I can maintain my weight indefinitely” and one participant commenting that “it is possible to lose weight and keep it off and feel better about yourself with a simple and systematic approach.” CONCLUSION: These findings support a short-term WLM program, based on social cognitive theory, in the maintenance of weight loss, while also promoting an increase in self-efficacy. This program has the potential to sustain both the functional and symptomatic improvements achieved through weight loss for older adults with knee OA.

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