Social vulnerability and heat on emergency medical services in San Antonio, Texas, 2015-2018

Abstract

Abstract Background A burgeoning body of research indicates that excessive heat is a leading weather-related cause of fatalities in the United States. The average annual heat-related deaths in the U.S. are about 1,500, which are more than deaths resulting from all natural disasters combined. Extreme heat conditions are also associated with non-fatal medical complications. More importantly, socially and economically disadvantaged or vulnerable populations can face greater exposure to health risks during extreme heat events. The purpose of this study is to investigate the effects of excessive heat and community-level social vulnerability on morbidity in San Antonio, Texas, from 2015 to 2018. Methods Heat Index data were collected from the San Antonio International Airport weather station, including the dates from May 1, 2015 to September 30, 2018. Social vulnerability was measured by the Centers for Disease Control and Prevention's Social Vulnerability Index at the zip-code level. Morbidity was gauged by the number of Emergency Medical Service incidents. Sixty-two zip codes in the San Antonio area were analyzed for the 612 constrained calendar days from May 1 to September 30, 2015-2018. Three time-stratified case-crossover negative binomial regression models were estimated to examine the independent effects of Heat Index and Social Vulnerability Index as well as the interaction effects of Heat Index and Social Vulnerability Index on the rate of Emergency Medical Services incidents. Results Both Heat Index and Social Vulnerability Index are significantly and positively associated with the rate of Emergency Medical Services incidents. Additionally, while Heat Index increases the rate of EMS incidents, the rate is even higher as social venerability becomes more pronounced. Conclusions As the number of excessive heat days increases and San Antonio continues to have extreme disparities by location, there will be an effect on health systems, including emergency medical services. Key messages Excessive heat and community-level social vulnerability are significantly and positively associated with emergency medical service incidents. There is a significant and positive interaction effect of heat and social vulnerability on emergency medical service incidents.