1138. Characteristics of Hospitalized Influenza Patients: A Comparison between Seasonal and Pandemic H1N1 Influenza in the United States
Session: Poster Abstract Session: Influenza and H1N1 Diagnosis, Epidemiology, and Viral Outcome
Saturday, October 22, 2011
Room: Poster Hall B1
  • Flu poster presentation_IDSA 2011.pdf (337.7 kB)
  • Background: We aimed to describe and compare characteristics of patients who were hospitalized with seasonal influenza during 2006-2007, 2007-2008 and 2008-2009, as well as the 2009-2010 H1N1 pandemic in the USA.

    Methods: De-indentified data from the Premier Perspective Hospital Database were analyzed.  To compare characteristics across seasons, F-tests were conducted.

    Results: A total of 34,350 hospitalizations with primary influenza diagnoses using the International Classification of Diseases, 9th Edition codes were identified.  Almost half (47%) occurred during the pandemic. The proportion of hospitalized pregnant women was highest during the pandemic (2.7%).  The 2007-2008 season had the highest median age of hospitalization at 60 years [interquartile range (IQR): 21 – 79); the 2008-2009 season had the lowest at 24 years (IQR: 2 – 61). Unlike the pandemic, seasonal influenza was characterized by higher proportions of patients younger than 15 years and 65 years and older. Median length of hospitalization did not vary by season, but did increase with increasing age -  patients younger than 15 years had a median length of stay of 2 days (IQR: 2 – 4), versus 5 days (IQR: 3 – 8) for those 65 years and older.  The most prevalent comorbidities were fluid and electrolyte disorders (16.8%), chronic pulmonary disease (14.6%) and hypertension (11.0%).  The highest proportion of prescribed neuraminidase inhibitors was during the pandemic (71%); the lowest was during the 2008-2009 season (35.9%).  Frequency of adamantanes prescriptions was highest (8.2%) for the 2008-2009 season.  Most hospitalizations received antibiotics.  Median number of doses received per hospitalization was 7 (IQR: 2 – 24). Frequency of mechanical ventilation and extracorporeal membrane oxygenation (ECMO) were highest during the pandemic.  The following were significantly different (P < 0.05) across seasons: proportions of women, pregnant women, treatments prescribed, comorbid conditions and patients on mechanical ventilation.

    Conclusion: Unlike pandemic influenza, seasonal influenza was distinguished by bimodal age characteristics. Higher proportions of hospitalized pregnant women, mechanical ventilation and ECMO were observed during the pandemic.

    Subject Category: J. Clinical practice issues

    Vani Vannappagari, PhD1,2, Ella Nkhoma, PhD3, Nana Koram, PhD1, Larry Knapton, BS4 and Emily W. Bratton, MSPH1,5, (1)WorldWide Epidemiology, GlaxoSmithKline, Research Triangle Park, NC, (2)Gillings School of Global Public Health, University of North Carolina-Chapel Hill, Chapel Hill, NC, (3)HealthCore, Inc., Andover, MA, (4)GlaxoSmithKline, Research Triangle Park, NC, (5)Epidemiology, UNC-Chapel Hill Gillings School of Global Public Health, Chapel Hill, NC


    V. Vannappagari, None

    E. Nkhoma, None

    N. Koram, None

    L. Knapton, None

    E. W. Bratton, None

    Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.