Abstract

LEON-GOMEZ, Inmaculada et al. Excess mortality associated with influenza in Spain in winter 2012. Gac Sanit [online]. 2015, vol.29, n.4, pp.258-265. ISSN 0213-9111.  https://dx.doi.org/10.1016/j.gaceta.2015.01.011.

Objective: An excess of mortality was detected in Spain in February and March 2012 by the Spanish daily mortality surveillance system and the "European monitoring of excess mortality for public health action" program. The objective of this article was to determine whether this excess could be attributed to influenza in this period. Methods: Excess mortality from all causes from 2006 to 2012 were studied using time series in the Spanish daily mortality surveillance system, and Poisson regression in the European mortality surveillance system, as well as the FluMOMO model, which estimates the mortality attributable to influenza. Excess mortality due to influenza and pneumonia attributable to influenza were studied by a modification of the Serfling model. To detect the periods of excess, we compared observed and expected mortality. Results: In February and March 2012, both the Spanish daily mortality surveillance system and the European mortality surveillance system detected a mortality excess of 8,110 and 10,872 deaths (mortality ratio (MR): 1.22 (95% CI:1.21-1.23) and 1.32 (95% CI: 1.29-1.31), respectively). In the 2011-12 season, the FluMOMO model identified the maximum percentage (97%) of deaths attributable to influenza in people older than 64 years with respect to the mortality total associated with influenza (13,822 deaths). The rate of excess mortality due to influenza and pneumonia and respiratory causes in people older than 64 years, obtained by the Serfling model, also reached a peak in the 2011-2012 season: 18.07 and 77.20, deaths per 100,000 inhabitants, respectively. Conclusion: A significant increase in mortality in elderly people in Spain was detected by the Spanish daily mortality surveillance system and by the European mortality surveillance system in the winter of 2012, coinciding with a late influenza season, with a predominance of the A(H3N2) virus, and a cold wave in Spain. This study suggests that influenza could have been one of the main factors contributing to the mortality excess observed in the winter of 2012 in Spain.

Keywords : Mortality; Influenza; Public health surveillance; Poisson regression; Time series; Serfling; Winter.

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