Heat and Health Service Use: A Spatiotemporal Analysis

Background While acute heatwaves are known to affect hospital presentations, less is known about broader health service use, regional disparities, or the effects of chronic climatic heat.

We analysed 20 years of weekly health service use data between 2002 and 2022 across all Australian Statistical Areas Level 4 (SA4s) geographies for four major health services: medical services (MBS), pharmaceuticals (PBS), hospital admissions, and emergency department (ED) presentations – by clinical category (cardiovascular, respiratory, mental health, other). Three population-weighted weather metrics were measured: weekly maximum temperature, heatwave events, and long-term climatic averages. Fixed-effects panel models were used to estimate short-term impacts of weather metrics on health service use while cross-sectional models were used to assess chronic exposure effects. Findings Acute exposure to dry temperature heatwaves was consistently associated with increased ED and inpatient presentations for mental health, cardiovascular, and other conditions. Apparent temperature heatwaves, incorporating humidity, showed more variable effects. MBS consultations rose modestly, while PBS dispensing declined during heat events. Long-term exposure to higher average temperatures was linked to increased inpatient care even after adjusting for socioeconomic status, remoteness, and health workforce. Disadvantaged regions experienced amplified effects, while areas with higher outdoor work exposure showed suppressed mental health care use. Interpretation Both acute and chronic heat exposures influenced health service demand across services and geographies during the study period. Heatwaves exacerbate existing healthcare inequalities and can disrupt access to medicines. Adaptation strategies must extend beyond hospitals to include primary and community-based care, with attention to population vulnerability and regional climate. Funding The International Centre for Future Health Systems receives funding from The Ian Potter Foundation. Competing Interest Statement The authors have declared no competing interest. Funding Statement The International Centre for Future Health Systems receives funding from The Ian Potter Foundation. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability All data produced in the present study are available upon reasonable request to the authors