Research article

Syndromic surveillance and heat wave morbidity: a pilot study based on emergency departments in France

Loïc Josseran¹ , Nadège Caillère¹ , Dominique Brun-Ney² , Jean Rottner³ , Laurent Filleul⁴ , Gilles Brucker¹ and Pascal Astagneau⁵

¹French Institute for Public Health Surveillance, Saint Maurice, France

²Assistance Publique des Hôpitaux de Paris, Paris, France

³Emergency Department, Mulhouse general hospital, Mulhouse, France

⁴Bordeaux Regional centre, French Institute for Public Health Surveillance, Bordeaux, France

⁵Department of public health, Pierre et Marie Curie University School of Medicine, Paris, France

author email corresponding author email

BMC Medical Informatics and Decision Making 2009, 9:14doi:10.1186/1472-6947-9-14

Published:	20 February 2009

Abstract

Background

The health impacts of heat waves are serious and have prompted the development of heat wave response plans. Even when they are efficient, these plans are developed to limit the health effects of heat waves. This study was designed to determine relevant indicators related to health effects of heat waves and to evaluate the ability of a syndromic surveillance system to monitor variations in the activity of emergency departments over time. The study uses data collected during the summer 2006 when a new heat wave occurred in France.

Methods

Data recorded from 49 emergency departments since July 2004, were transmitted daily via the Internet to the French Institute for Public Health Surveillance. Items collected on patients included diagnosis (ICD10 codes), outcome, and age. Statistical t-tests were used to compare, for several health conditions, the daily averages of patients within different age groups and periods (whether 'on alert' or 'off alert').

Results

A limited number of adverse health conditions occurred more frequently during hot period: dehydration, hyperthermia, malaise, hyponatremia, renal colic, and renal failure. Over all health conditions, the total number of patients per day remained equal between the 'on alert' and 'off alert' periods (4,557.7/day vs. 4,511.2/day), but the number of elderly patients increased significantly during the 'on alert' period relative to the 'off alert' period (476.7/day vs. 446.2/day p < 0.05).

Conclusion

Our results show the interest to monitor specific indicators during hot periods and to focus surveillance efforts on the elderly. Syndromic surveillance allowed the collection of data in real time and the subsequent optimization of the response by public health agencies. This method of surveillance should therefore be considered as an essential part of efforts to prevent the health effects of heat waves.