Trajectories of rehabilitation use among ageing adults with osteoarthritis in Canada: protocol for a population-based cohort study with latent class growth analysis of Canadian Longitudinal Study on Aging data.

INTRODUCTION: This study aims to explore use trajectories of rehabilitation services among ageing Canadians (45-85 years) with osteoarthritis. METHODS AND ANALYSIS: We will conduct a population-based cohort study using data from the Canadian Longitudinal Study on Aging (CLSA). We will describe rehabilitation use among respondents with osteoarthritis of the knee, hip or hand at baseline, 3-year and 6-year follow-up. Rehabilitation service use is measured via a single self-reported item capturing contact with a physiotherapist, occupational therapist or chiropractor in the past 12 months. We will use latent class growth analysis to identify 6-year trajectories of rehabilitation use, assigning participants to a single trajectory based on their highest probability of trajectory membership. All analyses will be stratified by income and within each income bracket by sex, gender and age. CLSA sampling weights will be applied to produce population estimates. ETHICS AND DISSEMINATION: Ethics approval for this study was obtained from the Research Ethics Board of Western University (REB #128991), Ontario Tech University (REB #17980) and the Canadian Memorial Chiropractic College (REB# 242014). Informed consent was obtained from all CLSA participants at the time of recruitment. Findings will be disseminated through peer-reviewed publications and presentations at national and international conferences, with relevance for researchers, clinicians and policymakers working to improve equitable access to rehabilitation for ageing Canadians.