Headlines - The Impact of Heat Waves on Healthcare Utilization: A Literature Review

In France, the health crisis caused by the 2003 heat wave starkly highlighted the seriousness of heat-related risks and prompted authorities to implement an action plan to prevent an increase in mortality during heat waves. Climate change suggests that heat waves will become more intense and frequent, with potentially serious associated health risks, against a backdrop of increasing vulnerability among the population due to aging and growing urbanization. In this context, it is important to better understand the dynamics between extreme temperatures, healthcare utilization, and mortality in order to improve prevention and limit the impact of heat waves. A review of the scientific literature conducted by the French Institute for Public Health Surveillance analyzed articles published up to January 2013 on the impact of heat waves or high temperatures on indicators of healthcare utilization. Thirty-nine articles were selected, including two concerning France. Most studies highlight a much greater impact on mortality than on morbidity, particularly when considering overall indicators, regardless of the interpretation of the indicators or the method of analysis. This makes it difficult to interpret healthcare utilization indicators for early warning purposes: a small impact on morbidity could mask a larger impact on mortality or a delayed impact. This discrepancy implies that some of the affected individuals die prematurely without having been treated by the hospital system, which raises questions about the effectiveness of preventive measures.The international literature helps advance our understanding of the potential and limitations of the surveillance system in the face of a growing risk. It is noted that available studies describe vulnerable populations based on demographic (age) and medical (reasons for seeking care) criteria. However, mortality studies have shown that socioeconomic factors also play a very significant role. It would therefore be useful to refine the prevention plan based on data regarding the socioeconomic characteristics of individuals who use the healthcare system during heat waves.