Clinical characteristics and outcomes of H1N1-associated pneumonia among adults in South Korea

BACKGROUND: Pneumonia has been reported to be the most life-threatening complication of infl uenza virus infection.OBJECTIVE: To describe clinical characteristics and determine risk factors for death among patients with H1N1- associated pneumonia.DESIGN: A retrospective cohort study included all adult patients diagnosed and treated with H1N1-associated pneumonia in 14 participating institutions between 1 May 2009 and 28 February 2010 in South Korea.Clinical outcomes were summarised and predictors for death evaluated through univariate and multivariate analysis.RESULTS: A total of 269 adult patients with H1N1- a ssociated pneumonia were diagnosed and treated.Hospital visits or admissions peaked in November 2009, coinciding with the peak in the 2009 H1N1 epidemic in South Korea.The patients' median age was 48 years; 143 were male.Most (n = 266, 98.9%) were admitted for treatment: 97 (36.1%) required intensive care and 28 (10.4%) needed mechanical ventilation.Despite the use of antiviral and antibacterial agents, 19 patients (7.1%) died.Risk factors predictive of death included presence of malignancy (aOR 12.0, 95%CI 2.8-51.5), and pneumonia severity index (PSI) score (aOR 1.03, 95%CI 1.01-1.04).CONCLUSION: Deaths among adult patients with H1N1-associated pneumonia were not rare.Clinicians should be aware of the possibility of a poor prognosis among H1N1-associated pneumonia patients with underlying malignancy or high PSI score.