The University of Louisville Journal of Respiratory Infections


Background: Reports from the 2009 H1N1 influenza A virus (2009 H1N1) pandemic indicate increased mortality in obese patients hospitalized with pneumonia. However, articles published prior to the pandemic have suggested that obesity may be a protective factor for mortality in these patients. The objective of this study was to compare the impact of obesity on mortality in hospitalized patients with pneumonia due to the 2009 H1N1 versus pneumonia due to other etiologies.

Methods: This was a secondary analysis of the CAPO international cohort study. Study groups were defined as follows: Group One, pneumonia due to 2009 H1N1: Patients hospitalized with pneumonia after March 2009 with a positive RT-PCR for 2009 H1N1 and Group Two, pneumonia due to other etiologies: Patients hospitalized with pneumonia before March 2009. Body Mass Index (BMI) was used to predict the influence of obesity on mortality. The effect of BMI on mortality was analyzed using a propensity-adjusted logistic regression model.

Results: From the total of 897 patients, 215 (24%) had pneumonia due to 2009 H1N1. After adjustment, increased BMI was associated with increased mortality in patients with pneumonia due to 2009 H1N1 and with decreased mortality in patients with pneumonia due to other etiologies.

Conclusions: Obesity is associated with poor outcomes in patients with pneumonia due to 2009 H1N1 but is protective in patients with pneumonia due to other etiologies. Defining the molecular mechanisms by which obesity influences outcomes in patients with pneumonia may help to develop novel therapeutic strategies.

Funding: US Department of Homeland Security.


This work was partially funded by a grant from the Kentucky Critical Infrastructure Protection Program, National Institute of Hometown Security and the United States Department of Homeland Security.



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