Endpoints met
The trial met its primary endpoint of a significantly greater reduction in pain at 18 months in the diet and exercise group as measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and scored on a scale of 0 (no pain) to 20 (worst pain).
In an analysis adjusted for sex, BMI, and baseline values, there was a 32% reduction in pain scores from baseline in the active intervention arm versus 24% in the control arm (P = .02).
In all, 60.2% of participants assigned to diet and exercise had a minimum reduction in pain scores of at least 2 points at 18 months, compared with 49.7% of participants assigned to the attention control group. This translated into a relative risk for achieving at least a 2-point improvement with diet and exercise was 1.20 (P = .01).
Among participants who remained in the study for the entire 18 months, there were significant improvements in the diet and exercise group compared with controls in the prespecified secondary endpoints of weight change (–8 kg vs. –2 kg), waist circumference, WOMAC function, 6-minute walk distance, and mean Short Form–36 health-related quality of life subscale (P < .001 for all comparisons).
Dr. Messier acknowledged that the diagnosis of knee OA was based only on ACR clinical criteria and was not confirmed with imaging. In addition, offering patients the option of free meal replacement limited the pragmatic nature of the intervention.
He also noted that the 24% reduction in pain seen in the control group suggests that interacting with patients can improve clinical outcomes.
‘Tour de force’
In the question-and-answer session following Dr. Messier’s presentation, David T. Felson, MD, a rheumatologist at Boston Medical Center, called in and said the study was “a tour de force” and congratulated Dr. Messier and colleagues on “a lovely study.”
Richard Mark Kirkner/MDedge News
Dr. David Felson
Dr. Felson asked whether the investigators had conducted a mediation analysis to determine what proportion of the improvement was attributable to weight loss, and whether patients assigned to exercise were sticking with it throughout the study.
Dr. Messier replied that they had not yet done a mediation analysis but were continuing to examine the data. Regarding the exercise question, he noted that “the adherence was over 80% for 6 months and over 70% for the whole 18 months, so they did a really nice job.”
In an interview, session moderator Anne Davidson, MBBS, director of the rheumatology program at Northwell Health in Manhasset, N.Y., commented that the investigators managed to accomplish a very challenging task.
“In terms of recruitment of patients with engagement of community facilities and quality of data, I would say that, as far as an osteoarthritis study goes, this was really a tremendous effort on the part of all people involved,” she said.
She noted that, while the WE-CAN program may work in North Carolina, there may be barriers to implementing it elsewhere, such as large suburban areas where some patients experience food insecurity and others have difficulty with transportation and access to treatment facilities.
“The question here that remains is, as Dr. Felson asked, what is the contribution of weight loss and what is the contribution of exercise? Because if it’s just weight loss, we have a whole lot of new things coming to help with that,” she said.
The WE-CAN study was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Dr. Messier disclosed that GNC, a health food and nutrition chain, donated the meal replacements used by patients. Dr. Davidson reported no relevant conflicts of interest.