Quantifying the Financial Burden of Heat-Related Hospital Admissions in Switzerland under a Changing Climate: A Scalable Analytical Framework

Background: While heat-related mortality is well-documented, the full economic burden of non-fatal illness remains underexplored. This gap hinders evidence-based health planning in a warming climate. We aimed to quantify the current and projected financial burden of heat-related hospital admissions in Switzerland. Methods: We linked daily hospital admissions (1998–2022) from six Swiss cantons, representing 60\% of the national total, to temperature records using a Distributed Lag Non-Linear Model (DLNM) meta-analysis. Costs were estimated via the Swiss Diagnosis-Related Groups (SwissDRG) tariff system across different disease categories and age groups.Future climate projections were generated using CH2018 climate simulationswith Shared Socioeconomic Pathway scenarios (SSP1-RCP2.6, SSP2-RCP4.5, SSP5-RCP8.5). Findings: Historically, extreme heat significantly increased hospital admissions in major Swiss regions, with endocrine/metabolic disorders showing the highest risk (Relative Risk 2.02). The elderly (75+) and children were the most vulnerable populations. The average annual cost of these direct hospitalizations across the six cantons studied was CHF 20.6 million (2013--2022), notably a conservative estimate representing only a fraction of the total economic burden. Future projections show this burden escalating sharply. Under a high-emissions pathway (SSP5-RCP8.5), these direct costs are projected to increase 2.5-fold by the 2060s, with costs for the elderly quintupling.Critically, even with aggressive mitigation (SSP1-RCP2.6), costs are still projected to triple compared to the baseline. This is driven primarily by demographic aging, with climate change acting as a significant amplifier, responsible for 15--30\% of the projected cost increases for the elderly. Interpretation:Our findings from major Swiss regions reveal a substantial and growing financial burden on the healthcare system. Given that these figures represent a \textit{lower bound}, the true costs are likely much higher. This evidence underscores the urgent need for nationally coordinated adaptation policies to protect public health and ensure healthcare sustainability, even as mitigation efforts continue.