Last update:
31-Mar-2011

OBJECTIVE In April 2009 the first cases of novel influenza A H1N1 were registered in Mexico, since when the disease spread rapidly worldwide, becoming a pandemic. This paper describes the clinical features and course of the disease in adults hospitalized with proven H1N1 infection in a reference center in Athens, and explores the risk factors for H1N1 pneumonia.

METHOD Retrospective medical chart reviews were made to collect data on the hospitalized patients. H1N1 infection was confirmed in specimens with the use of a realtime reverse transcriptase-polymerase chain reaction assay (RT-PCR).

RESULTS From 15th May to 15th September 2009, 58 patients were hospitalized with H1N1 infection, of whom 52% presented with flu-like symptoms and had a benign course. Nearly 30% had one or more underlying medical conditions. A total of 28 of the 58 patients (48%) presented with pneumonia, and there were 7 intensive care admissions, but no deaths. Four patients developed acute respiratory distress syndrome (ARDS) and therefore required mechanical ventilation. The patients with pneumonia were older (36 vs 26, p=0.003), more hypoxemic (39% vs 7%, p=0.01) and presented higher serum levels of alanine aminotransferase (SGOT) (43.2 vs 25.5, p=0.01), creatine phosphokinase (CPK) (418 vs 127.5, p=0.01) and lactate dehydrogenase (LDH) (345 vs 171, p=0.002) than the other patients hospitalized with H1N1.

CONCLUSIONS During the evaluation period (May−August 2009) it was observed that H1N1 influenza can cause pneumonia devoid of bacterial infection, with prognostic factors for its development being high serum levels of LDH at admission and the smoking habit.

Key words: Athens, H1N1, Hospitalization, Influenza, Patients.