Stepped-care obesity interventions show no effect on knee OA remission

A stepped-care approach offering tailored, gold standard interventions for obesity in people with OA has shown no effect on remission rates in an Australian randomised controlled trial.

When interventions starting with as weight loss and exercise were offered as part of a 32-week stepped-care package  to overweight and obese people with medial tibiofemoral OA there was no clinical or significant effect on remission of pain, patient global assessment of disease activity and/or functional impairment, a Sydney University study found.

In the study, 87 adults over the age of 50 with knee OA and with a body mass index ≥28 kg/m2 were assigned to a two-step intervention, starting with an 18-week diet and exercise program. Based on clinical response, patients were then allocated to a second step offering continued diet and exercise or interventions designed to manage depression (CBT), varus malalignment (unloader knee brace) and muscle weakness (strengthening exercises).

However when compared to a control group of 84 patients who received usual care, there was no significant impact on the primary endpoint of disease remission rate derived from patient acceptable symptom state (PASS) criteria for pain plus the patient global assessment of disease activity and/or functional impairment.

Remission at 32 weeks was achieved by 39% of patients in the stepped-care group and in 26% of the control group. The difference of 12.6% (p=0.10) was less than the 25% level deemed to be clinically relevant, said researchers led by Dr Sarah Robbins (PhD) of the Institute of Bone and Joint Research, Kolling Institute of Medical Research, and Department of Rheumatology, Royal North Shore Hospital, Sydney.

In findings published in Arthritis Care and Research, they noted that patients in the stepped-up care group showed an improvement in pain and function between baseline and 20-weeks. The improvement was maintained in functional improvement at 32-weeks, but pain levels tended to get worse between weeks 20 and 32.

Patients in the stepped up care group showed significant levels of weight loss at 20 weeks (-6.1kg vs. -0.1kg)  and 32 weeks (-5.3kg vs. 0.2kg) compared to the control group. There was also a significant decrease in the number of MRI detected bone marrow lesions (from 7.1  to 6.5) in patients who wore the knee brace from week 20 to 32. However there was no change in quadriceps strength after training.

Significantly higher rates of perceived improvement were reported by patients in the stepped care group in comparison to the control (59% vs 41%, respectively) and most of the improvement seems to have occurred in the first step.

The researchers said some of the perceived improvement in the stepped care group may have come from the additional attention received from the care support team and the knowledge of being allocated to the experimental group and consequent expectation of getting better from it.

They suggested that future trials of stepped care focus on design of the second step to address issues such as underpowering of subgroups and lack of guidance for people allocated to subgroups.

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