Epidemiology, clinical features, and prognosis of elderly adults with severe forms of influenza A (H1N1

Abstract

Objectives: 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.

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

Setting: One hundred forty-eight Spanish ICUs.

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

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

Results: 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, P = .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).

Conclusion: 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.