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. 2011 Jul 28;15(4):R182.
doi: 10.1186/cc10331.

When should a diagnosis of influenza be considered in adults requiring intensive care unit admission? Results of population-based active surveillance in Toronto

Stefan P Kuster  1 , Kevin C Katz, Joanne Blair, James Downey, Steven J Drews, Sandy Finkelstein, Rob Fowler, Karen Green, Jonathan Gubbay, Kazi Hassan, Stephen E Lapinsky, Tony Mazzulli, Donna McRitchie, Janos Pataki, Agron Plevneshi, Jeff Powis, David Rose, Alicia Sarabia, Carmine Simone, Andrew Simor, Allison McGeer
Affiliations

When should a diagnosis of influenza be considered in adults requiring intensive care unit admission? Results of population-based active surveillance in Toronto

Stefan P Kuster et al. Crit Care. .

Abstract

Introduction: There is a paucity of data about the clinical characteristics that help identify patients at high risk of influenza infection upon ICU admission. We aimed to identify predictors of influenza infection in patients admitted to ICUs during the 2007/2008 and 2008/2009 influenza seasons and the second wave of the 2009 H1N1 influenza pandemic as well as to identify populations with increased likelihood of seasonal and pandemic 2009 influenza (pH1N1) infection.

Methods: Six Toronto acute care hospitals participated in active surveillance for laboratory-confirmed influenza requiring ICU admission during periods of influenza activity from 2007 to 2009. Nasopharyngeal swabs were obtained from patients who presented to our hospitals with acute respiratory or cardiac illness or febrile illness without a clear nonrespiratory aetiology. Predictors of influenza were assessed by multivariable logistic regression analysis and the likelihood of influenza in different populations was calculated.

Results: In 5,482 patients, 126 (2.3%) were found to have influenza. Admission temperature ≥38°C (odds ratio (OR) 4.7 for pH1N1, 2.3 for seasonal influenza) and admission diagnosis of pneumonia or respiratory infection (OR 7.3 for pH1N1, 4.2 for seasonal influenza) were independent predictors for influenza. During the peak weeks of influenza seasons, 17% of afebrile patients and 27% of febrile patients with pneumonia or respiratory infection had influenza. During the second wave of the 2009 pandemic, 26% of afebrile patients and 70% of febrile patients with pneumonia or respiratory infection had influenza.

Conclusions: The findings of our study may assist clinicians in decision making regarding optimal management of adult patients admitted to ICUs during future influenza seasons. Influenza testing, empiric antiviral therapy and empiric infection control precautions should be considered in those patients who are admitted during influenza season with a diagnosis of pneumonia or respiratory infection and are either febrile or admitted during weeks of peak influenza activity.

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Figures

Figure 1
Figure 1
Comparison of influenza activity by laboratory surveillance in Ontario. Data are expressed as the percentage of specimens submitted to reference virology laboratories yielding influenza, 2007/08 and 2008/09 influenza seasons and second wave of the 2009 H1N1 influenza pandemic (light grey bars: influenza B; dark grey bars: influenza A), as well as the corresponding number of patients admitted to participating ICUs with influenza (black line).
Figure 2
Figure 2
Study subjects. Flowchart of study subjects requiring admission to ICUs in Toronto during the 2007/08 and 2008/09 influenza seasons and the second wave of the 2009 H1N1 influenza pandemic.
See this image and copyright information in PMC

Comment in

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