Heat-attributable hospitalisation costs in Sydney: Current estimations and future projections in the context of climate change

The association between heat and diseases has been extensively reported. However, its associated healthcare costs and attributable fraction due to heat were scarcely explored. The aim of this study was to estimate hospitalisation costs attributable to heat in Sydney, and to project future costs under climate change scenarios. Using a distributed lag nonlinear model, this study estimated heat-attributable hospitalisation costs in Sydney; and using 2010–2016 data as baseline, future costs for 2030s and 2050s were estimated under three climate change scenarios depending on greenhouse gas emissions - Representative Concentration Pathway (RCP)2.6, RCP4.5, and RCP8.5. Higher temperatures were found to be associated with increased hospitalisation costs. About 8–9% of the total hospitalisation costs were attributable to heat. The total costs attributable to heat over the baseline period 2010–2016 were estimated to be AU$252 million, with mental health hospitalisation making the largest contribution. Hospitalisation costs are estimated to increase substantially to AU$387–399 million in the 2030s, and AU$506–570 million by mid-century under different climate change scenarios. Urgent action is required to reduce heat-attributable illness in our communities, particularly for mental health conditions. Relevant preparations including healthcare workforce capacity building and resource allocation are needed to deal with these challenges in the context of climate change.