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


CONCLUSIONS
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.
Josseran
Loïc
L
French Institute for Public Health Surveillance, Saint Maurice, France. l.josseran@invs.sante.fr
Caillère
Nadège
N
Brun-Ney
Dominique
D
Rottner
Jean
J
Filleul
Laurent
L
Brucker
Gilles
G
Astagneau
Pascal
P
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003627:Data Interpretation, Statistical; D003681:Dehydration / Q000453:epidemiology; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005334:Fever / Q000453:epidemiology; D005602:France / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D007010:Hyponatremia / Q000453:epidemiology; D008875:Middle Aged; D009017:Morbidity; D010865:Pilot Projects; D011159:Population Surveillance / Q000379:methods*; D040442:Public Health Informatics / Q000379:methods*; D055815:Young Adult