General practitioners ending their practice and impact on patients' health, health care use and mortality. A protocol for national registry cohort studies in Norway, 2006 to 2021.

IntroductionContinuous general practitioner (GP) and patient relations associate with positive health outcomes. Termination of GP-practice is unavoidable, while consequences of final breaks in relations are less explored. We will study how an ended GP-relation affects patients health care utilization and mortality, compared to patients with a continuous GP-relation. Methods and analysisLinking personal-level national registries data on GP-affiliation, sociodemographic characteristics, health care use and mortality, from 2008 to 2021, we will identify patients of GPs terminating practice, and match these GP-patient pairs on age, sex (both), immigrant status and education (patient), and number of patients and practice period (GPs), to GP-patient pairs with a continuous relationship in other municipalities, and compare acute and elective primary and specialist health care use mortality, before and after ended GP-practice, using Poisson regression with high-dimensional fixed effects. We will address expected modifying factors, such as patients with complex health care needs, quality of termination and GP-availability in the municipalities. Ethics and disseminationThis study protocol is part of the approved project Improved Decisions with Causal Inference in Health Services Research, 2016/2158/REK Midt (the Regional Committees for Medical and Health Research Ethics) and does not require consent. We will publish in peer-reviewed journals, accessible in NTNU Open, and present at scientific conferences. To reach a broader audience, we will summarize articles in the projects web page, regular and social media, and disseminate to relevant stakeholders. Strengths and limitations of this studyThis study adds to research on GP-patient relation continuity and associations, exploring termination of relations and designing a natural experiment in register data, facilitating causal inference. The study includes the entire Norwegian population and their general practitioners (GPs) from 2008 to 2021, linking several mandatory, high-quality, healthcare, and demographic registers on a personal level. The register data include exact time points (xxx or months? xxx) for the intervention, termination of GP-relation, and the outcomes, health care utilization and death. By matching GP-patient pairs in practice period and distinct municipalities, we minimize time-varying confounders and dilution of effects. As in all observational studies, our results may be influenced by residual confounding