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. 2010 Mar 9;182(4):349-55.
doi: 10.1503/cmaj.091823. Epub 2010 Feb 16.

Risk of severe outcomes among patients admitted to hospital with pandemic (H1N1) influenza

Alexia Campbell  1 , Rachel Rodin, Rhonda Kropp, Yang Mao, Zhiyong Hong, Julie Vachon, John Spika, Louise Pelletier
Affiliations

Risk of severe outcomes among patients admitted to hospital with pandemic (H1N1) influenza

Alexia Campbell et al. CMAJ. .

Abstract

Background: We describe the disease characteristics and outcomes, including risk factors for admission to intensive care unit (ICU) and death, of all patients in Canada admitted to hospital with pandemic (H1N1) influenza during the first five months of the pandemic.

Methods: We obtained data for all patients admitted to hospital with laboratory-confirmed pandemic (H1N1) influenza reported to the Public Health Agency of Canada from Apr. 26 to Sept. 26, 2009. We compared inpatients who had nonsevere disease with those who had severe disease, as indicated by admission to ICU or death.

Results: A total of 1479 patients were admitted to hospital with confirmed pandemic (H1N1) influenza during the study period. Of these, 1171 (79.2%) did not have a severe outcome, 236 (16.0%) were admitted to ICU and survived, and 72 (4.9%) died. The median age was 23 years for all of the patients, 18 years for those with a nonsevere outcome, 34 years for those admitted to ICU who survived and 51 years for those who died. The risk of a severe outcome was elevated among those who had an underlying medical condition and those 20 years of age and older. A delay of one day in the median time between the onset of symptoms and admission to hospital increased the risk of death by 5.5%. The risk of a severe outcome remained relatively constant over the five-month period.

Interpretation: The population-based incidence of admission to hospital with laboratory-confirmed pandemic (H1N1) influenza was low in the first five months of the pandemic in Canada. The risk of a severe outcome was associated with the presence of one or more underlying medical conditions, age of 20 years or more and a delay in hospital admission.

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Figures

Figure 1
Figure 1
Severity of outcome by age among 1473 cases of pandemic (H1N1) influenza in patients admitted to hospital that were reported from Apr. 26 to Sept. 26, 2009. (Information on age missing for six patients.) ICU = intensive care unit.
Figure 2
Figure 2
Epidemic curve of laboratory-confirmed cases of pandemic (H1N1) influenza in patients admitted to hospital that were reported from Apr. 26 to Sept. 26, 2009, by date of symptom onset or collection of specimen.
See this image and copyright information in PMC

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