Long-term weight loss of at least 20% helps improve outcomes in overweight, obese patients with knee osteoarthritis

Obese and overweight patients who lose at least 20% of their body weight and maintain the weight loss over the long term may have better physical health-related quality of life, less pain, and improved function than those who lose less weight, according to a recent study.

Researchers performed a secondary analysis of the diet only and diet plus exercise groups in the randomized controlled Intensive Diet and Exercise for Arthritis (IDEA) study. Overweight and obese adults with pain and radiographically confirmed knee osteoarthritis who had participated in IDEA were characterized according to their weight loss over 18 months: less than 5%, at least 5%, at least 10%, and at least 20%. Pain and function as measured by the Western Ontario McMasters Universities Osteoarthritis Index (WOMAC), mobility as measured by six-minute walk distance, health-related quality of life as measured by the Short-Form 36 Health Survey, knee joint compressive force, and inflammation as measured by interleukin-6 levels were among the variables evaluated at baseline, six-month follow-up, and 18-month follow-up. The study results were published June 18 by Arthritis Care & Research.

A total of 72.1% of patients in the study were women, and 85.0% were white. Mean age was 65.8 years. The mean percentage of weight change was 0.2% in 74 patients in the less than 5% group, 7.4% in 59 patients in the at least 5% group, 14.5% in 76 patients in the at least 10% group, and 24.6% in 31 patients in the at least 20% group. Overall, a statistically significant dose response with weight loss was found for pain (P=0.01), function (P=0.0006), six-minute walk distance (P<0.0001), physical and mental health-related quality of life (P=0.0004 and 0.03, respectively), knee joint compressive force (P<0.0001), and interleukin-6 level (P=0.002). Clinical and mechanistic outcomes were most improved in the group that lost the most weight (≥20%). That group outperformed those who lost less than 5% of their body weight and those who lost at least 5% on all measures and had 25% less pain and better function than the group that lost at least 10%, in addition to a statistically significant improvement in physical health-related quality of life (P=0.006).

The researchers noted that their study was observational and that relatively few patients lost at least 20% of their body weight, among other limitations. They concluded that large differences in intentional weight loss lead to large differences in health outcomes in this population. “We suggest that standard of care for older, overweight and obese adults with knee [osteoarthritis] should include, at minimum, a 10% weight loss using the techniques developed in previous successful weight loss trials,” the authors wrote. “An additional 10% weight loss has the added benefit of significantly improved physical health related quality of life, and a clinically important reduction in pain and improvement in function.”