1776. Effect of Age and Comorbidity on 2009 Pandemic H1N1-Related ICU Stay in Massachusetts
Session: Poster Abstract Session: Viral Infections; Pathogenesis and Epidemiology
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C
  • 1776_IDWPOSTER_HPlaczek.pdf (1.5 MB)
  • Background: Statewide population-based comparisons of predictors of severe seasonal influenza and pandemic H1N1(pdm) by age strata have not been conducted in the United States. We do not know how comorbidity measures compare by age strata between influenza seasons.

    Methods: We identified those discharged with ILI-related diagnoses between 10/01/2008-04/25/2009 and H1N1pdm-related diagnoses between 04/26/2009-09/30/2009 within the Hospital Inpatient Discharge Database (HIDD) in Massachusetts. We calculated the Diagnostic Cost Group (DxCG) risk score for each individual as a comorbidity measure. Using random effects logistic regression models, we identified and compared characteristics and predictors of H1N1pdm- and ILI-related ICU stay within the full study population, and by age strata.

    Results: Average DxCG scores were similar for H1N1pdm and seasonal influenza (n=4,874; 0.69 and 0.70). We found higher ICU admission rates among younger age groups during the H1N1pdm time period (11% vs. 10%, p<0.05), and a greater number of deaths among those <18 years during the H1N1 pandemic compared to the seasonal influenza period. Statistically significant results from the full multivariate model indicate that compared to those 45-64 years old, those <5 yrs, 5-12, and 13-18 yrs had increased risk for H1N1pdm-related ICU stay (OR = 1.40, 2.01, and 2.26, respectively). For all, increased DxCG score was associated with ICU stay (OR=2.20 for each unit increase in score). Within the H1N1pdm cohort, a diagnosis for asthma was highly predictive of ICU admission among those <5, 5-12, and 13-18 years (OR=2.66, 3.43, 3.74, respectively), and pregnancy among those 26-44 years (OR=4.09).

    Conclusion: This is the first study to report statewide risk-based score calculations and outcomes by age strata in all acute care hospitals in Massachusetts during the first wave of the 2009 H1N1 pandemic. We found higher ICU rates and numbers of deaths in the H1N1pdm-specific group. Those <18 years were at increased risk of ICU stay, after adjusting for comorbidity. Increasing DxCG score increased odds for ILI-related ICU admission. We conclude that H1N1pdm caused more severe disease in hospitalized younger age groups compared to seasonal influenza, despite similar measures of comorbidity between H1N1pdm and seasonal influenza groups.

    Hilary Placzek, PhD, MPH, Healthcore, Inc., Andover, MA; Dept of Clinical and Population Health Research, University of Massachusetts Medical School, Worcester, MA and Lawrence Madoff, MD, FIDSA, Epidemiology and Immunization, Massachusetts Department of Public Health, Jamaica Plain, MA; Medicine, University of Massachusetts Medical School, Jamaica Plain, MA; William A. Hinton State Lab Inst, Jamaica Plain, MA; International Society for Infectious Diseases, Brookline, MA


    H. Placzek, None

    L. Madoff, None

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