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Epidemiology, Clinical Features, and Prognosis of Elderly Adults with Severe Forms of Influenza A (H1N1)


Address correspondence to Dr. José Garnacho-Montero, Avda. Manuel Siurot s/n, 41013 Seville, Spain. E-mail:



To examine epidemiological and clinical data of individuals aged 65 and older with influenza virus A (H1N1) admitted to the intensive care unit (ICU) and to identify independent predictors of ICU mortality.


Prospective, observational, multicenter study to determine prognostic factors in individuals infected with influenza A (H1N1) admitted to the ICU.


One hundred forty-eight Spanish ICUs.


Individuals with influenza A (H1N1) confirmed using real-time polymerase chain reaction from April 2009 to July 2011.


Individuals aged 65 and older were compared with younger individuals. A multivariate analysis was conducted to determine independent predictors of mortality in this population.


One thousand one hundred twenty individuals (129 (11.5%) aged ≥65) were included. Prevalence of chronic diseases was more common in older individuals. Viral pneumonitis was more frequent in individuals younger than 65 (70.5% vs 54.3%, P < .001). In older individuals, Acute Physiology and Chronic Health Evaluation II score (odds ratio (OR) = 1.11, 95% confidence interval (CI) = 1.11–1.20, = .002), immunosuppression (OR = 3.66, 95% CI, 1.33–10.03, P = .01) and oseltamivir therapy initiated after 48 hours (OR = 3.32, 95% CI = 1.02–10.8, P = .04) were identified as independent variables associated with mortality. Corticosteroid use was associated with a trend toward greater mortality (OR = 2.39, 95% CI = 0.98–5.91, P = .06).


Individuals aged 65 and older with influenza A (H1N1) admitted to the ICU have a higher incidence of underlying diseases than younger individuals and differences in clinical presentation. Early oseltamivir therapy is associated with better outcomes in elderly adults.

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