Background: We analyzed the underlying cause of death recorded in hospitalized patients with laboratory-confirmed influenza.
Methods: The present study included all patients with a laboratory-confirmed diagnosis of influenza during the influenza seasons 2009-2010 to 2013-2014 who were attended to in hospital and died. Their underlying cause of death according to the International Classification of Diseases 10th Revision was obtained from the Navarre Mortality Registry.
Results: Among 49 patients studied, the underlying causes of death were 35% influenza, 4% pneumonia, 14% other respiratory diseases, 10% circulatory disease and 37% other causes.
Conclusions: Non-cardiorespiratory causes accounted for a third of deaths in patients with confirmed influenza, thus all-cause mortality should be considered in estimating the full burden of influenza mortality.