Longitudinal costs and health service utilisation associated with primary care reforms in Ontario: a retrospective cohort study protocol

Introduction Over the last 20 years, the Canadian province of Ontario implemented several new models of primary care focusing on changes to physician remuneration, clinics led by nurse practitioners and the introduction of interprofessional primary care teams. Health outcome and cost evaluations of these models thus far have been mostly cross-sectional and in some cases results from these studies were conflicting. The aim of this population-based study is to investigate short, medium and long-term effectiveness of these reforms over the past 15-20 years. Methods and analysis This is the protocol for a retrospective cohort study including fee-for-service (FFS) and community health centre cohorts (control cohorts) or patients who switched from either being unattached or from FFS to a new practice model (eg, capitation, enhanced FFS, team, nurse practitioner-led) from 1997 to 2020. The primary outcome is total healthcare costs and secondary outcomes are primary care costs, other (non-primary care) health costs, hospitalisations, length of stay, emergency department visits, accessibility and mortality. A combination of hard and propensity matching will be used where relevant. Outcomes will be adjusted for demographic and health factors and measured annually. Interrupted time series models will be used where data permits and difference-in-differences methods will be used otherwise. Ethics and dissemination Ethics approval has been received from Queens University and Memorial University. The dissemination plan includes conference presentations, papers, brief evidence summaries targeted at select audiences and knowledge brokering sessions with key stakeholders.