Heatwave-health vulnerability in Adelaide: Analysis of mortality and morbidity outcomes

Abstract

Background: Heatwaves are of increasing concern due to its impacts on population health (mortality/morbidity). As heatwave-impacts varies between populations and locations, evidence concerning the places and people vulnerable at a local level is critical for effective policy, planning, and interventions, especially in a warming climate. This study part of a larger national research aimed to investigate heatwave-associated mortality and morbidity (using general practitioner-GP visits) in Adelaide and identify the drivers of heatwave-vulnerability. Methods: Data on mortality (2007-2017), GP visits (2011-2016), heatwaves (Excess Heat Factor-EHF), and vulnerability factors (socio-demographic, health-risk, and environmental) were obtained from the Australian Bureau of Statistics, Bureau of Meteorology, and Geoscience Australia. Heatwave effects on mortality and morbidity outcomes at the Statistical Area Level 2 (SA2) geography (representing suburbs) were estimated using a case-crossover design. Results are reported as relative risks (RRs) in heatwaves periods compared with non-heatwave periods. Effect modification by individual- and area-level factors were also assessed. Results: Mortality increased during heatwaves (RR 1.08; 95%CI: 1.04-1.12) but varied spatially. Higher RRs were found in areas with a greater proportion of renters, inaccessibilities (access to vehicle/internet), less vegetation, newer houses, and prevalence of respiratory and psychological diseases. Risks were elevated among individuals with limited English-speaking ability, diabetes, asthma/chronic obstructive pulmonary diseases and those using antidepressants, anxiolytics and sedative medications. Preliminary analysis of GP visits with EHF reveals a significant decrease in GP visits (RR 0.98; 95%CI:0.98-0.99) during low-intensity heatwaves, which increased during severe/extreme heatwaves (RR 1.14; 95%CI: 1.13-1.15). Analysis of the individual- and area-level drivers of heatwave-related GP visits is ongoing. Conclusions: Our results, leveraging a substantive person and area-level dataset, show that heatwaves increase mortality and place a greater burden on primary care services (GPs) in Adelaide. Attention to the spectrum of identified heatwave-vulnerability drivers is key for developing effective and efficient prevention strategies.