IJE Advance Access originally published online on March 6, 2008
International Journal of Epidemiology 2008 37(2):317-318; doi:10.1093/ije/dyn020
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Commentary: Evaluating response to heat waves
*CREAL-IMIM, Barcelona, Spain. E-mail: jsunyer{at}imim.es
Accepted 17 January 2008
Following the heat wave of 2003 in Europe, intervention programs have been adopted in many countries (http://ec.europa.eu/health/ph_information/dissemination/unexpected/unexpected_3_en.htm). Among them, the Heat Health Watch Warning system implemented by the ‘Insitute de Veille Sanitaire’ in France, together with a Heat Wave National Plan are probably the most detailed and exhaustive (http://www.sante.gouv.fr/canicule). In this issue, Fouillet et al.1 evaluate the effectiveness of the measures undertaken in France and conclude that during the heat wave which occurred in July 2006, there were 2065 excess deaths in the total French population, instead of the 5452 that would have occurred given the temperature levels, in the absence of the intervention (i.e. the same circumstances that at baseline, the summer of 2003). The evaluation of intervention programs has a poor record in epidemiology, despite the widespread adoption of heat health interventions in many European regions. There has been only one formal evaluation of a preparedness program in Milwakke (USA).2 Additionally, Tan et al.3 compared the determinants of the impact of two heat waves in Shangai (China) where deaths were reduced in the second wave although meteorological conditions were similar in both episodes.
The assessment of the effectiveness of an intervention depends on the model used to predict the daily mortality rates. Authors showed that their model yielded excellent predictions of the death counts observed for four consecutive summers. It predicts the number of deaths for a given day and summer, based on temperatures observed during 28 consecutive summers from 1975 to 2003. This model assumes that daily mortality is influenced by very short-term variations in daily temperatures (the previous 10 days), and taking reference based on temperature data in spring and fall to estimate a trend in mortality. However, the fact that only summer data was included (and not data from the whole year) does not allow controlling for variation in the proportion of frail population in different summers that could depend on mid-term effects such as influenza epidemics occurring during the preceding winter season. One of the explanations for the high mortality occurring in summer of 2003 was the lack of influenza the previous winter.
Furthermore, the model uses a single temperature for the whole France, and although authors accept the advantage of having finer tuning using data specific for smaller geographical areas, it would be desirable to assess evaluation of programs allowing for differences between city and rural area. It is well known that cities have a peculiar ecosystem that increases the general temperature.
Population heterogeneity is well considered by Fouillet et al. showing a higher susceptibility among the elderly (although contrary to the authors’ statement, this is debateable among women). A point that intervention programs do not address refers to specific populations occurring during summer, such as tourists and temporal open-air workers. These populations were in general not included in the plans, nor in the evaluation.
Overall, we welcome evaluation of interventions such as Fouillet et al. did which open a new epidemiological field of research in the global climate change arena.
 |
References |
|---|
 Top References |
|---|
1 Fouillet A, Rey G, Wagner V, et al. Has the impact of heat waves on mortality changed in France since the European heat wave of summer 2003? A study of the 2006 heat wave. Int J Epidemiol (2008) 37:309–17.
2 Weisskopf MG, Anderson HA, Foldy S, et al. Heat wave morbidity and mortality, Milwaukee, Wis, 1999 vs 1995: an improved response? Am J Public Health (2002) 92:830–33.
3 Tan J, Zheng Y, Song G, Kalkstein L, Kalkstein A, Tang X. Heat wave impacts on mortality in Shanghai, 1998 and 2003. Int J Biometeorol (2007) 51:193–200.[CrossRef][Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||