Identification of Influenza Cases During the H1N1 Pandemic in Massachusetts Using Population-Based Hospital Discharge Data
Student Authors
Hilary PlaczekUMass Chan Affiliations
Department of Medicine, Division of Infectious Diseases and ImmunologyDocument Type
Journal ArticlePublication Date
2011-08-14Keywords
Influenza, Human; Influenza A Virus, H1N1 Subtype; Hospitalization; Epidemiologic Factors; MassachusettsImmunology and Infectious Disease
Influenza Humans
Life Sciences
Medicine and Health Sciences
Public Health
Metadata
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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.Source
PLoS Curr. 2011 Aug 14;3:RRN1256. Link to article on publisher's websiteDOI
10.1371/currents.RRN1256Permanent Link to this Item
http://hdl.handle.net/20.500.14038/33213PubMed ID
21858253Related Resources
Link to article in PubMedRights
This research note is distributed under the Creative Commons Attribution 3.0 license.ae974a485f413a2113503eed53cd6c53
10.1371/currents.RRN1256