How is the user base of general practices associated with Open or Closed Books in Aotearoa New Zealand? An analysis of administrative data.

Introduction In Aotearoa New Zealand (NZ), general practices are able to close their books, meaning that they do not enrol any new patients at all. This can increase the barriers that people face in accessing health care and may affect different groups disproportionately. Aim This study aimed to examine the link between the enrolling status of general practices and the characteristics of the population in areas served by these practices, ie the user base, across New Zealand. Methods Regression models, with bootstrapping, were used to explore the relationship between Open and Closed Books general practices and the variables: sex, median age, total count ethnicity, being born in New Zealand, median personal income, the New Zealand Deprivation Index 2023, health status, and the Urban Accessibility Index in the area surrounding the general practices. Results Being a Closed Books general practice was more likely when the user base had higher proportions of people born in New Zealand, had lower health status, were Māori or European, were female, and lived in a large or medium urban area. It was less likely when there were higher proportions of males and Asian peoples. After adjusting for Health Districts, only one variable, being born in New Zealand, remained significant. Discussion Characteristics of the user base were associated with a general practices' enrolling status and mediated by location. These findings contribute to a deeper understanding of the inequalities affecting access to primary health care and point to the potential of geographically tailored approaches to minimise disparities and promote healthcare equity.