By Emily Delzel
Education about weight loss—including why it’s important and how to achieve it—should be “front and center” of any clinical encounter involving patients with knee osteoarthritis (OA), said a researcher who recently published findings on the effects of weight change over time on OA-related pain and functional limitations.
Daniel L. Riddle, PT, PhD, from Virginia Commonwealth University in Richmond, VA, and Paul Stratford, MSc, PT, from McMaster University in Hamilton, Ontario, CA, whose study was e-published in April by Arthritis Care & Research, found that weight changes of 10% or more produced clinically meaningful changes in pain and function in patients with knee OA.
The researchers analyzed information from two large data sets with cohorts of community-based individuals with or at high risk for knee OA, the Osteoarthritis Initiative (OAI) and the Multicenter
Osteoarthritis Study (MOST).
Riddle noted one of the current study’s main strengths was its analysis of the effects of weight change in a more natural setting than those of trials aimed specifically at weight loss.
“In such trials participants receive extensive training and attention designed to affect weight change; our study looks at the natural effect of weight gain and loss without the superseding effects of investigator attention and a weight loss intervention,” he said.
The analysis included OAI and MOST participants who had radiographic evidence of knee OA as well as OA-related pain and functional limitations. Investigators assessed body weight at baseline and follow up (OAI, 3 years; MOST, 30 months), along with pain and function changes as scored using the WOMAC (Western Ontario and McMaster Universities) arthritis index. Patients from the OAI and MOST databases (62.2% and 64.5% women, respectively) had mean baseline weights of 190.6 pounds and 205.8 pounds, respectively.
Investigators grouped individuals into five categories based on percent weight change at follow up. Participants who lost 10% or more of their baseline body weight had significantly less function-related pain and improved function compared with the reference group (4.9% reduction to 4.9% gain). Individuals who gained 10% or more of their starting weight had significantly worse pain and function compared with the reference group.
“Our results provide a solid threshold for the magnitude of weight patients need to lose to feel a clinically significant impact,” Riddle said, and noted that long-term, meaningful weight loss often requires a more intensive intervention than a single clinician can provide.
In a second April study, e-published in Pain, investigators at Duke University in Durham, NC, looked at interventions for weight loss in patients with knee OA. The investigators randomized overweight and obese adults with painful knee OA to pain coping skills training (PCST) plus behavioral weight management (BWM); PCST alone; BWM alone; or standard care.
At 12 months patients in the PCST plus BWM group had significantly better outcomes for pain, physical disability, and a number of psychological measures including self-efficacy and pain catastrophizing than the other groups; they also lost significantly more weight (an average of 5% of their baseline weight).
“OA and weight challenges are often conceptualized as separate treatment challenges but this study highlights the importance of helping patients with OA who are overweight or obese learn to cope more effectively with their pain and their weight,” said Tamara Somers, PhD, assistant professor of psychiatry and behavioral sciences at Duke and study lead author.
The PCST plus BWM intervention was intensive, involving many hours of training from skilled psychologists and exercise physiologists.
“There are a number of ways these interventions might be implemented to be more accessible to patients,” she said. “Intervention components could potentially be delivered in gyms or facilities such as community centers and churches. Another option is delivering interventions with mobile or electronic health technologies.”
Riddle, DL, Stratford PW. Body weight changes and corresponding changes in pain and function in persons with knee osteoarthritis. Arthritis Care Res 2012 April 13. [Epub ahead of print.]
Somers TJ, Blumenthal JA, Guilak, et al. Pain coping skills training and lifestyle behavioral weight management in patients with knee osteoarthritis: A randomized controlled study. Pain 2012 April 12. [Epub ahead of print.]