The Paradigm of Disaster Exposure and All-Cause Hospital Admissions in Rural New South Wales, Australia

Climate change-related disasters pose significant challenges to healthcare systems globally. Understanding their impact on hospital utilisation, particularly considering socioeconomic vulnerabilities, is essential for effective health system resilience. The main goal of this study is to assess how exposure to major natural disasters, specifically bushfires, floods, and total disaster events, affects all-cause hospital admission rates in NSW, Australia. A quasi-experimental Difference-in-Differences (DiD) study was conducted using data from NSW Local Government Areas (LGAs) over a defined pre and post disaster period. The primary outcome was the all-cause hospital admission rate per 100 population. Multiple models were used to estimate the DiD effects for total disaster events, bushfires, and floods; while controlling for time and socioeconomic status, as measured by deciles of the Index of Relative Socioeconomic Advantage and Disadvantage (IRSAD). A strong socioeconomic gradient was consistently observed, with significantly lower baseline hospital admission rates in LGA with less socioeconomic disadvantage compared to the most disadvantaged areas (p < 0.004 for Deciles 2-10 vs. Decile 1). The DiD analysis yielded counterintuitive results regarding the impact of disasters. Exposure to any major disaster was associated with a relative decrease in the admission rate trend compared to unexposed areas (-2.23, p-value=0.006), after controlling for socioeconomic status. Bushfire exposure showed a similar, marginally negative trend (-1.93, p-value=0.054) with no significant impact found for flood exposure (p-value=0.39). Contrary to expectations, this study found that exposure to major disasters in NSW was associated with a relative decrease in the trend of all-cause hospital admissions after controlling for socioeconomic status. These findings suggest complex dynamics that may influence overall admission trends. The results highlight the significant impact of underlying socioeconomic disadvantage on baseline healthcare utilisation, emphasising the need for targeted public-health strategies and disaster management planning that considers both baseline vulnerabilities and potential access barriers during disasters.