01.30.2016
Weight loss of more than 10% produced the greatest improvement
by Wayne Kuznar
Contributing Writer
More weight loss translates to greater improvement of knee osteoarthritis (OA) symptoms, an international team of researchers has found.
Image from MedPageToday
In a community-based study, a dose-response relationship was found between weight loss and symptom improvement in knee OA, with weight reduction of more than 10% being associated with greater improvement in symptoms and function in knee OA compared with weight loss of 2.5% to 5% of body weight.
“This study established a clear dose-response relationship between weight loss and symptom improvement in overweight and obese people with knee OA undergoing a standardized weight loss program in a community setting,” wrote David J. Hunter, MBBS, PhD, and co-investigators.
“It demonstrates that weight loss is feasible in this setting with the majority of participants having lost a significant amount of weight over the 18 weeks and nearly one third achieving more than 10% weight loss.”
For the study, which appeared online in Arthritis Care & Research, 1,383 consecutive persons with symptomatic knee OA, 71% of whom were female, were enrolled in an 18-week weight loss program, the Osteoporosis Healthy Weight For Life Program. All patients were deemed to have knee OA symptoms that were or were likely to require referral to an orthopedic surgeon for evaluation for knee joint replacement.
Program recommendations were as follows: a goal of more than 5% weight loss for overweight individuals, aerobic exercise in the form of walking and swimming, muscle strengthening, and self-management and education strategies.
The intervention consisted of three 6-week phases that incorporate a portion-control eating plan, an activity plan that included strength, balance and mobility exercises, online symptom, progress, satisfaction tracking, two-way personal motivation, support, and advice. The program’s aim was to achieve a weight loss of 7% to 10% over the 18 weeks. The 18-week program was followed by an open-ended long-term maintenance phase.
Participants were assessed at baseline, 6 weeks, and 18 weeks for body weight and Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire subscales. The KOOS is scored on a 0 to 100 scale, with 0 representing extreme knee problems and 100 no knee problems. The Western Ontario McMaster Universities Arthritis Index (WOMAC) function score was derived from the KOOS, with a higher WOMAC score indicating a higher degree of functional impairment. Participants’ average weight at baseline was 95.1 kg and 82% were obese, with an average body mass index of 34.4 kg/m2.
At baseline, mean KOOS subscale scores were 56.3 for pain, 54.3 for other symptoms, 59.5 for function in daily living, 27.6 for function in sports and recreation, and 35.1 for knee-related quality of life.
During the study period, 1,304 (94.2%) participants had a reduction in body weight of more than 2.5%. The mean weight loss was 7.9 kg, which amounted to 8.3% of baseline body weight.
Some 5.7% of participants lost less than 2.5% of their body weight, 16.2% lost 2.5% to 5%, 24.0% lost 5.1% to 7.5%, 22.9% lost 7.6% to 10%, and 31.2% lost more than 10% of their body weight.
A significant dose-response relationship between the change in each of the KOOS subscales and the percentage of weight change across all weight change categories was observed even after adjusting for age, gender, baseline weight, and baseline KOOS measures.
The group with the largest amount of weight loss (10% or more) had the greatest improvement in pain, function, and other KOOS domains.
A loss in body weight of at least 7.7% was required to achieve a minimal clinically important improvement in the WOMAC. (An absolute change of 5.3, 11.8, and 20.5 in the WOMAC function score is required for a minimal clinically important improvement in those who start with low, intermediate, and high baseline WOMAC scores, respectively.)
A minimal clinically important improvement in WOMAC function was achieved in those participants who lost at least 7.7% of body weight. Those with a higher level of functional impairment at baseline required a higher percentage of body weight loss to achieve a minimal clinically important improvement in function.
“This study is unique in that it demonstrates the feasibility of dietary intervention, coupled with motivational support, in a true-to-life community setting,” the investigators wrote.
“It is noteworthy that the entire dietary intervention was supported by remotely delivered interventions, which were web, paper, or telephone-based. In addition, this project demonstrated the effectiveness of focusing on weight loss per se in improving knee OA symptoms.”
The findings “emphasize the importance of weight loss in improving symptoms and function in overweight/obese persons with knee OA,” they added, as obesity is associated with poor functional outcome in this condition.
The main limitations of the study were the lack of a control group, the inability to evaluate the utility of the components of the program on functional improvement, and the possibility of introducing bias by not evaluating those patients who discontinued the program.
One author is the CEO and scientific director of Prima Health Solutions, which delivers the Healthy Weight for Life program. None of the other investigators has a commercial or financial relationship.
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