Severe virus influenza A H1N1 related pneumonia and community-acquired pneumonia: differences in the evolution.

Objective: To analyze the clinical, laboratory and evolution data of patients with severe influenza A H1N1 pneumonia and compare the data with that of patients with severe community-acquired bacterial pneumonia.

Methods: Cohort and retrospective study. All patients admitted to the intensive care unit between May 2009 and December 2010 with a diagnosis of severe pneumonia caused by the influenza A H1N1 virus were included in the study.