Effects of a Weight Loss Program in People With Hip Osteoarthritis

Clinical guidelines recommend exercise as the core treatment for symptoms, but provide conflicting recommendations about weight loss for people with hip OA. Irrefutable health benefits are associated with weight loss for those with overweight or obesity, but it remains uncertain whether weight loss in addition to exercise and regular physical activity is superior to exercise alone for hip OA symptoms. This study is a randomized controlled trial for which the aim is to determine whether a weight loss and exercise program improves hip pain more than an exercise program alone at 6 months among people with hip OA who have overweight or obesity. A total of 100 people with hip osteoarthritis and overweight or obesity will be recruited from the community. Participants will be assessed for eligibility, including review of a hip x-ray. They will be enrolled into the study following informed consent and completion of baseline questionnaires and laboratory-based measures. Each participant will be randomly allocated to receive either: a) weight loss plus exercise program or; b) exercise program alone, over 6 months. The randomisation schedule will be prepared by a biostatistician (permuted block sizes 2 to 6) stratified by site and sex. Participants allocated to the exercise group will be randomly allocated to a physiotherapist. Participants allocated to the exercise plus weight loss group will be randomly allocated to one of the same physiotherapists as the exercise group, and to a dietitian. The schedule will be stored on a password-protected platform at the University of Melbourne and maintained by a researcher not involved in either participant recruitment or administration of outcome measures. Group allocation will be revealed after completion of baseline measures and randomisation. Dietitians will complete training in best-practice OA management (half day workshop led by investigators), motivational interviewing skills (2-day training course), weight management (the ketogenic very low calorie diet) and trial procedures. Physiotherapists will be trained in trial procedures, best practice OA management, strengthening and physical activity program, behaviour change techniques to promote adherence and resources for use in the program. Study participants in both groups will attend 5 individual physiotherapy consultations via video-conference over 6 months and will undertake a home-based lower limb muscle strengthening exercise and physical activity program. Those in the weight loss and exercise group will also undertake a ketogenic very low calorie diet (VLCD), which has been demonstrated as a safe and effective means of achieving rapid weight loss in the adult population with overweight/obesity. They will receive meal replacements (maximum 2 per day) for up to 6 months as well as educational resources. A biostatistician will analyse blinded data. The statistical method will be outlined in a Statistical Analysis Plan.