[Factors associated to admission to Intensive Care in patients hospitalized due to pandemic Influenza A/H1N1 2009].

Objective: The present study explores the possible factors related to severe cases of pandemic flu.

Design: A retrospective cohort study was conducted in patients hospitalized with Influenza A/H1N1 2009 during the pandemic period.

Setting: Ramon y Cajal University Hospital (Madrid, Spain).

Patients: All hospitalized patients with positive RT-PCR (real-time polymerase chain reaction) for Influenza A/H1N1 2009 virus.

Main Variables: The main variables collected were: history of risk factors for severe Influenza, history of immunization, clinical presentation, laboratory tests, chest X-ray report, administration of antiviral treatment, and hospital stay.

Results: The median age of the 100 cases was 38 years (range 4 months to 80 years). Seventy-seven percent of the patients had at least one risk factor. Asthma was the most common factor among patients younger than 18 years, versus smoking in the older subjects. Antiviral therapy was initiated a median time of three days (range 0 to 18 days) after the onset of illness. Nineteen percent of the patients were admitted to Intensive Care, and 2% died. Metabolic disease and abnormal chest X-ray findings were factors associated to admission to the ICU.

Conclusion: As in other studies, abnormal chest X-ray findings upon admission and metabolic disease were related to poor outcomes of 2009 pandemic Influenza A (H1N1) infection in our patients.