Development and Implementation of Emergency Department based Heat related Illness Active Surveillance System: Effect of Heat Index on Daily Emergency Department Visits due to Heat related Illness

ABSTRACT

PURPOSE: To evaluate the effect of heat wave on emergency department (ED) visits due to heat related illness, we developed an ED based active surveillance system. We want to identify epidemiology of ED visits due to heat related illness and determine the effect of heat index on daily ED visits due to heat related illness. METHODS: We developed an ED based active surveillance system for adults who visited the ED due to heat stroke, heat exhaustion, heat syncope, heat edema, and heat cramp. We collected demographic and clinical variables, risk factors, and heat index by standardized registry on the webpage. We operated the surveillance into 16 emergency departments in Daegu City from June to September 2011. We analyzed epidemiologic variables descriptively and assessed the effect of heat index on the number of daily ED visits by multivariate Poisson regression analysis. RESULTS: During the study period, 34 cases were registered and nine cases were heat stroke. Heat stroke patients were older, and had more unemployment status than those with other heat related illness (p<0.05). More ED visits due to heat related illness were observed during the danger period than during the cool period, classified by heat index severity (Adjusted odds ratio 1.72, 95% CI 1.33-2.23). Increasing heat index by one degree caused more ED visits due to heat related illness (Adjusted incident rate ratio 1.13, 95% CI 1.07-1.19). CONCLUSION: We developed an ED based active surveillance system and observed more elderly persons and lower educational level in patients with heat stroke. In addition, increase in heat index significantly affected more daily ED visits due to heat related illness.