A Community-based Adaptation of the Small Changes Behavioural Weight Loss Treatment Approach for Psoriatic Arthritis Patients With Comorbid Obesity

Background: Psoriatic Arthritis (PsA) is an inflammatory auto-immune disorder that impacts approximately 3-in-10 patients with skin psoriasis. Compared to other rheumatologic conditions, patients with PsA are at a higher risk of having comorbid obesity (i.e., BMI ≥30 kg/m2; present in 44% of PsA cases). Treating patients with PsA and comorbid obesity presents a unique challenge due to added complications of attenuated pharmacological response to treatment, and mobility issues that impact quality of life for patients. While weight-loss is known to help alleviate symptom burden and improve quality of life in patients with PsA and comorbid obesity, few studies have investigated behavioural weight-loss treatment (BWLT) in patients with PsA to support sustained weight-loss over time.

Aims: The primary aim of the proposed trial will evaluate feasibility metrics (i.e., recruitment rate, drop-out, intervention fidelity, acceptability) of a randomized controlled clinical trial testing an adaptation of a validated "small changes"-based BWLT approach. The secondary aim is to examine differences in mean weight loss, self-reported PsA symptoms (e.g., pain, mobility) and health related quality of life (HRQOL) between patients randomized to BWLT versus patients in the control condition who receive treatment as usual (at a community-based rheumatology clinic).

Methods: The proposed study is a single center, open label parallel-group randomized control feasibility trial. Our study will control for the effect of treatment as usual in a community-based rheumatology clinic (i.e., medication and behaviour self-management). Patients will undergo baseline assessments and then will be randomized (1:1) to either the "small changes" BWLT or treatment as usual (TAU). The Small Changes BWLT is a cognitive-behavioural treatment program that was developed as an alternative to traditional behavioral therapy based on high treatment failure rates and weight regain across time - particularly in high-risk populations. Patients are provided with education on weight loss-promoting behaviour changes and encouraged to set SMALL [Self-selected, Measurable, Action-Oriented, Linked to your Life, and (Time) Limited] goals aimed at increasing self-efficacy and satisfaction, while decreasing feelings of deprivation in order to achieve sustained, long term weight loss in participants. The BWLT group will receive 16, weekly, 2-hour group-based sessions led by an undergraduate-level coach (i.e., BKin). Content covered includes nutrition, physical activity, mindfulness, cognitive restructuring, managing stress, sleep, social support, and problem-solving and is consistent with recent Canadian obesity treatment guidelines. The TAU group will received usual care from the Balfour community rheumatology clinic in Penticton, B.C. Feasibility metrics (i.e., drop-out/retention rates, patient adherence, patient-reported satisfaction with the BWLT etc.) will be assessed at the primary endpoint of 24-weeks post-randomization. Secondary outcomes (weight loss, PsA symptoms, HRQOL) will be

Impact/Future Directions: The results from the proposed study will be used to inform and develop a subsequent, adequately powered, randomized controlled efficacy trial investigating the primary outcome of weight-loss among patients with PsA and obesity who receive a BWLT, relative to TAU controls. Ultimately, the implementation of the BWLT to a community-based rheumatology clinic has potential to improve the quality of life in patients with PsA and comorbid obesity.