Received 8 October 2010; returned 9 November 2010; revised 2 December 2010; accepted 6 December 2010Objectives: The impact of oseltamivir on mortality in critically ill patients with 2009 pandemic influenza A(2009 H1N1) is not clear. The main objective of this study was to investigate the relationship between thetiming of antiviral administration and intensive care unit (ICU) outcomes.Methods: Prospective, observational study of a cohort of ICU patients with confirmed 2009 H1N1 infection.Clinical data, treatment and outcome were compared between patients receiving early treatment (ET) withoseltamivir, initiated within 2 days, and patients administered late treatment (LT), initiated after this timepoint.Multivariate analysis and propensity score were used to determine the effect of oseltamivir on ICU mortality.Results: Six hundred and fifty-seven patients were enrolled. Four hundred and four (61.5%) patients requiredmechanical ventilation (MV; mortality 32.6%). Among them, 385 received effective antiviral therapy andwere included in the study group. All patients received oseltamivir for a median duration of 10 days (interquar-tile range 8–14 days). Seventy-nine (20.5%) ET patients were compared with 306 LT patients. The two groupswere comparable in terms of main clinical variables. ICU length of stay (22.7+16.7 versus 18.4+14.2 days;P¼0.03), hospital length of stay (34.0+20.3 versus 27.2+18.2 days; P¼0.001) and MV days (17.4+15.2versus 14.0+12.4; P¼0.04) were higher in the LT group. ICU mortality was also higher in LT (34.3%) than inET (21.5%; OR¼1.9; 95% CI 1.06–3.41). A multivariate model identified ET (OR¼0.44; 95% CI 0.21–0.87) asan independent variable associated with reduced ICU mortality. These results were confirmed by propensityscore analysis (OR¼0.44; 95% CI 0.22–0.90; P,0.001).Conclusions: Our findings suggest that early oseltamivir administration was associated with favourableoutcomes among critically ill ventilated patients with 2009 H1N1 virus infection.Keywords: antiviral treatment, prognosis, pneumonia
