Evaluating the Impact of Heat Warning Systems on Mortality and Morbidity: A Systematic Review

Background Heat exposure poses a significant global health risk, leading to approximately 7 deaths per 100,000 individuals annually. Implementing heat warning systems(HWS) aims to mitigate the health impacts of extreme heat events. This systematic review evaluates the effectiveness of these systems in reducing heat-related morbidity and mortality. Methodology A systematic search of Embase and PubMed databases was conducted using terms related to heat warning systems and health outcomes. Studies were limited to English-language research articles from the United States and Canada, focusing on studies that assess the impact of HWS on morbidity and mortality outcomes. Results Four articles assessed the relationship between HWS and mortality. One study reported a significant reduction in heat-related deaths, with reductions between 17% and 51% of expected rates. Another study noted an average of 2.6 lives saved per day due to HWS implementation. However, two studies found no significant association between HWS and all-cause mortality, with relative risk values of 1.005 (95% CI: 0.997, 1.013) and a per cent change in mortality of -0.5% (95% CI: -2.8, 1.9). Regarding morbidity, three studies indicated mixed results. One study showed increased hospitalizations for fluid and electrolyte disorders (RR: 1.040 [95% CI: 1.015, 1.065]) and heat stroke (RR: 1.094 [95% CI: 1.038, 1.152]), while another reported a 17% to 51% reduction in paramedic emergency medical service runs. The third study found no significant differences in overall health services use. Conclusion This review reveals a complex relationship between heat warning systems (HWS) and heat-related mortality and morbidity. While some studies show significant reductions in deaths, others indicate that HWS alone may not sufficiently lower overall mortality rates. Localized strategies that consider socioeconomic factors and healthcare access are essential, along with continuous improvement of HWS. Future research should examine regional variations to develop tailored approaches for specific heat-related health issues.