Prevention of Incident Knee Osteoarthritis by Moderate Weight Loss in Overweight and Obese Females

Objective. This study evaluated the effect of moderate weight loss on the incidence of knee osteoarthritis (OA) in middle-aged overweight and obese women, without clinical and radiologic knee OA at baseline. Methods. A total of 353 women (87%) with followup data available were selected from the Prevention of Knee Osteoarthritis in Overweight Females study, which evaluated the preventive effect of a diet and exercise intervention and of oral glucosamine sulfate on the incidence of knee OA. This was an exploratory proof-of-concept analysis, which compared the incidence of knee OA between women who reached the clinically relevant weight loss target of 5 kg or 5% of body weight after 30 months and those who did not reach this target. Results. The weight loss group showed a significantly lower incidence of knee OA according to the primary outcome measure, which was composed of the American College of Rheumatology criteria (clinical and radiographic), Kellgren/ Lawrence grade >= 2, and joint space narrowing >= 1.0 mm (15% versus 20%; odds ratio 0.5, 95% confidence interval 0.3-0.9). Moreover, the weight loss also positively affected several health measures, such as blood glucose level, body fat percentage, and blood pressure. Conclusion. A reduction of 5 kg or 5% of body weight over a 30-month period reduces the risk for the onset of radiographic knee OA in middle-aged overweight and obese women. Because of the slow progression of the disease, a longer followup period will be necessary before the number of prevented cases of knee OA by moderate weight loss becomes clinically more relevant