Abstract
PURPOSE: This study aims to estimate the associations of general practitioner (GP) sex and age with patients’ use of specialist and out-of-hours healthcare services in Norway, using a quasi-experimental design that leverages patient assignment to a GP to reduce bias from patient-GP matching. METHODS: Using national registry data on 1,884,665 adult patients assigned to a GP from 2008 to 2021, we exploited quasi-random assignment of patients to GPs to estimate the associations of the assigned GP’s sex or age with patient healthcare utilization in the three years after assignment. Poisson regression analyses were used for binary outcomes (contact/no contact), and linear regressions for continuous measures (number of contact days) of healthcare utilization, each with multi-level fixed effects to adjust for confounding. Analyses were stratified by patient groups defined by history of mental health diagnosis. RESULTS: GP sex and age generally had small or null associations with healthcare utilization. A small negative association was observed for non-acute outpatient mental and somatic healthcare, but this was not consistent across groups defined by mental health diagnostic history. GP sex or age showed no consistent associations with other outcomes. CONCLUSION: As the GP workforce undergoes demographic changes—with an increasing share of younger and female physicians—these results suggest that such characteristics are unlikely to be strongly associated with individual patients’ use of specialist or out-of-hours mental and somatic healthcare services. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s43999-026-00086-4.