Published: Nov 16, 2014

By Wayne Kuznar , Contributing Writer, MedPage Today

Image from MedPageToday.com

Obese patients with knee osteoarthritis (OA) who maintain an initial weight loss report fewer symptoms compared with their baseline level of symptoms, Danish researchers reported in Arthritis Care & Research.

The improvement in symptoms was similar regardless of the weight maintenance program followed; either a dietary intervention, a program of knee exercises, or no formal intervention (controls). The results suggest that weight loss is the key component to knee OA pain relief, according to Henning Bliddal, MD, DMSc, of Copenhagen University Hospital, and colleagues.

The finding, which comes from an assessment of data from CAROT (Cartilage in Obese Knee Osteoarthritis Patients Trial), “confirms the feasibility of long-term weight loss maintenance in sedentary individuals, in this case patients with mobility limitations due to knee OA,” the authors wrote.

CAROT is a randomized controlled trial of patients 50 years and older with knee OA and a body mass index 30 kg/m2 who underwent a 16-week intensive dietary weight loss intervention before being randomized to one of three maintenance groups for 52 weeks. One group was randomized to a dietary intervention in which participants met weekly and were provided with formula products free of charge designed to enhance weight loss. A second group was randomized to a knee exercise program consisting of 3 days/week of circuit training. A third group received no intervention, but were informed that they would be contacted at 52 weeks.

The co-primary outcome was self-reported pain on a 100-mm Visual Analogue Scale (VAS) and the percentage of responders according to the OMERACT-OARSI responder criteria.

There were 192 patients in the intent-to-treat population, 89% of whom had bilateral knee OA. One hundred seventy five of the 192 completed the initial 16-week phase, and 16 of the completers withdrew from the study during the maintenance period. Weight loss was maintained in all three randomized groups but those assigned to the dietary maintenance program had the most success in maintaining their weight loss. This group had an average weight decline from baseline of 11.0 kg, compared with a 6.2-kg decline in the exercise group and an 8.2-kg decline in the control group. The difference in weight loss between the dietary maintenance group and the exercise group (P=0.0005) and between the dietary maintenance group and control group (P=0.043) was statistically significant.

All three groups had reductions in VAS pain from baseline to final visit (68 weeks after entry; 52 weeks after randomization to maintenance). Despite the superior weight loss in patients assigned to dietary intervention, this group had no significantly greater reduction in pain than the other two groups (–6.1 mm in dietary intervention group, –5.6 mm in the exercise group, and –5.5 mm in the control group). The decrease in pain on VAS from baseline in all groups was approximately 15%. There was no difference in pain scores between any of the groups at week 68.

Similarly, the OMERACT-OARSI success rates were not significantly different between groups (50%, 41%, and 52% in the dietary intervention, exercise, and control groups, respectively).

Among secondary outcome measures, there was no difference between groups in occurrence of radiographic disease progression.

The investigators hypothesize that the poorer weight loss maintenance in the exercise group may have been a product of the exercise program’s goal to reduce target knee OA pain and disability rather than to increase metabolic expenditure. “Furthermore, compliance with the facility-based parts of the exercise program was poor, and compliance with the home-based exercises was similarly poor, if not poorer,” they wrote.

When considered with the ADAPT and IDEA studies, which studied diet, exercise, or the combination of the two, “A common conclusion of all three trials is that diet is mandatory for the weight loss, while exercise has been given with varying compliance and effect,” they added.