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PLoS One. 2016 May 19;11(5):e0154970. doi: 10.1371/journal.pone.0154970. eCollection 2016.

Epidemiology of Hospital Admissions with Influenza during the 2013/2014 Northern Hemisphere Influenza Season: Results from the Global Influenza Hospital Surveillance Network.

Author information

1
Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO), Valencia, Spain.
2
D.I. Ivanovsky Institute of Virology FSBI "N.F. Gamaleya FRCEM" Ministry of Health of Russian Federation, Moscow, Russian Federation.
3
Research Institute of Influenza, St. Petersburg, Russian Federation.
4
National Influenza Reference Laboratory, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
5
Division of Infectious Disease, Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China.
6
School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.
7
Sanofi Pasteur, Lyon, France.
8
Centro de Investigación Biomédica en Epidemiología y Salud Publica (CIBER-ESP), Instituto de Salud Carlos III, Madrid, Spain.

Abstract

BACKGROUND:

The Global Influenza Hospital Surveillance Network was established in 2012 to obtain valid epidemiologic data on hospital admissions with influenza-like illness. Here we describe the epidemiology of admissions with influenza within the Northern Hemisphere sites during the 2013/2014 influenza season, identify risk factors for severe outcomes and complications, and assess the impact of different influenza viruses on clinically relevant outcomes in at-risk populations.

METHODS:

Eligible consecutive admissions were screened for inclusion at 19 hospitals in Russia, Turkey, China, and Spain using a prospective, active surveillance approach. Patients that fulfilled a common case definition were enrolled and epidemiological data were collected. Risk factors for hospitalization with laboratory-confirmed influenza were identified by multivariable logistic regression.

FINDINGS:

5303 of 9507 consecutive admissions were included in the analysis. Of these, 1086 were influenza positive (534 A(H3N2), 362 A(H1N1), 130 B/Yamagata lineage, 3 B/Victoria lineage, 40 untyped A, and 18 untyped B). The risk of hospitalization with influenza (adjusted odds ratio [95% confidence interval]) was elevated for patients with cardiovascular disease (1.63 [1.33-2.02]), asthma (2.25 [1.67-3.03]), immunosuppression (2.25 [1.23-4.11]), renal disease (2.11 [1.48-3.01]), liver disease (1.94 [1.18-3.19], autoimmune disease (2.97 [1.58-5.59]), and pregnancy (3.84 [2.48-5.94]). Patients without comorbidities accounted for 60% of admissions with influenza. The need for intensive care or in-hospital death was not significantly different between patients with or without influenza. Influenza vaccination was associated with a lower risk of confirmed influenza (adjusted odds ratio = 0.61 [0.48-0.77]).

CONCLUSIONS:

Influenza infection was detected among hospital admissions with and without known risk factors. Pregnancy and underlying comorbidity increased the risk of detecting influenza virus in patients hospitalized with influenza-like illness. Our results support influenza vaccination as a measure for reducing the risk of influenza-associated hospital admission.

PMID:
27196667
PMCID:
PMC4873033
DOI:
10.1371/journal.pone.0154970
[Indexed for MEDLINE]
Free PMC Article

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