Subjects hospitalized with the 2009 pandemic influenza A (H1N1) virus in a respiratory infection unit: clinical factors correlating with ICU admission

Respir Care. 2014 Oct;59(10):1560-8. doi: 10.4187/respcare.03049. Epub 2014 Aug 12.

Abstract

Background: The 2009 pandemic influenza A (H1N1) virus was accompanied by high morbidity and mortality. The aim of this study was to describe the clinical characteristics of patients with documented 2009 influenza A (H1N1) virus admitted to a reference chest hospital, the disease outcome, and risk factors associated with ICU admission.

Methods: We assessed 109 subjects admitted to the respiratory infection unit of a hospital for chest disease with signs and symptoms of the 2009 influenza A (H1N1) virus between April 2009 and December 2010. Demographic data, comorbidities, clinical signs and symptoms, laboratory tests, radiographic findings, treatment, and final outcomes were all recorded. Factors associated with severe disease requiring ICU admission were determined.

Results: Ninety subjects (82.5%) had laboratory-confirmed 2009 influenza A (H1N1). Sixty-four percent of these subjects had pneumonia on admission, 26% had respiratory failure, and 11% required care in the ICU. Dyspnea and the presence of infiltrates on chest x-rays were the most common signs among the subjects with H1N1. All subjects were treated with antiviral therapy, and 75% received antibiotic treatment based on their clinical and laboratory findings. The predictive factors of ICU admission were severe hypoxemia and lymphocytosis.

Conclusions: The outcome of subjects with influenza A (H1N1) virus infection was influenced by the severity of the disease on admission, the subjects' underlying conditions, and complications during hospitalization.

Keywords: hospitalization outcome; intensive care unit; pandemic H1N1 infection.

MeSH terms

  • Adult
  • Antiviral Agents / therapeutic use
  • Comorbidity
  • Disease Outbreaks*
  • Female
  • Greece / epidemiology
  • Hospitalization / statistics & numerical data*
  • Humans
  • Influenza A Virus, H1N1 Subtype*
  • Influenza, Human / epidemiology
  • Influenza, Human / therapy*
  • Influenza, Human / virology*
  • Intensive Care Units*
  • Length of Stay / statistics & numerical data
  • Male
  • Respiratory Care Units*
  • Respiratory Tract Infections / epidemiology
  • Respiratory Tract Infections / therapy*
  • Respiratory Tract Infections / virology*
  • Retrospective Studies
  • Risk Factors
  • Severity of Illness Index
  • Treatment Outcome

Substances

  • Antiviral Agents