GSBS Program
Clinical & Population Health Research Program
UMMS Affiliation
Department of Medicine, Division of Infectious Diseases and Immunology
Date
8-14-2011
Document Type
Article
Medical Subject Headings
Influenza, Human; Influenza A Virus, H1N1 Subtype; Hospitalization; Epidemiologic Factors; Massachusetts
Disciplines
Immunology and Infectious Disease | Influenza Humans | Life Sciences | Medicine and Health Sciences | Public Health
Abstract
Objectives:
(1) To characterize the epidemiology of H1N1-related hospitalizations in Massachusetts; and (2) to compare characteristics of those hospitalized during periods of seasonal influenza activity and during the H1N1 pandemic.
Methods:
Authors applied maximum and minimum criteria to the Massachusetts Hospital Discharge Database to identify H1N1-related hospitalizations. They constructed annual line graphs describing mean frequencies of influenza-like illness(ILI)-related discharges between 2005-2008, and compared these rates to early waves of H1N1 in 2009.
Results:
During spring and summer 2009, there were significantly higher rates of ILI-related hospital discharges in Massachusetts compared to 2005-2008. Out of 359,344 total discharges between April 26-September 30,2009, H1N1-related hospitalizations ranged from 601 to 10,967 cases. Minimum criteria confirmed that H1N1 affected a younger population (50% were <18>years), with higher rates among African-Americans (18%) and Hispanics (23%) and higher rates of ICU admission (21%) compared to seasonal influenza (39%, 10%, 14%, and 17% respectively).
Conclusions:
This is the first population-based assessment of epidemiological characteristics of hospitalized H1N1 cases in Massachusetts, and it is the first to include all possible hospitalized cases in the analysis. The authors confirm that large administrative data sets can detect hospitalizations for influenza during a pandemic, but estimated case counts vary widely depending on selection criteria used. Maximum criteria overestimated H1N1 activity, and those meeting minimum criteria resemble published accounts of H1N1-related hospitalizations closely.
Rights and Permissions
Citation: PLoS Curr. 2011 Aug 14;3:RRN1256. Link to article on publisher's website
Comments
This research note is distributed under the Creative Commons Attribution 3.0 License.