Outcomes of influenza A(H1N1)pdm09 virus infection: results from two international cohort studies.

<h4>Background</h4>Data from prospectively planned cohort studies on risk of major clinical outcomes and prognostic factors for patients with influenza A(H1N1)pdm09 virus are limited. In 2009, in order to assess outcomes and evaluate risk factors for progression of illness, two cohort st...

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Main Authors: Ruth Lynfield, Richard Davey, Dominic E Dwyer, Marcelo H Losso, Deborah Wentworth, Alessandro Cozzi-Lepri, Kathy Herman-Lamin, Grazyna Cholewinska, Daniel David, Stefan Kuetter, Zelalem Ternesgen, Timothy M Uyeki, H Clifford Lane, Jens Lundgren, James D Neaton, INSIGHT Influenza Study Group
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2014-01-01
Series:PLoS ONE
Online Access:https://doi.org/10.1371/journal.pone.0101785
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author Ruth Lynfield
Richard Davey
Dominic E Dwyer
Marcelo H Losso
Deborah Wentworth
Alessandro Cozzi-Lepri
Kathy Herman-Lamin
Grazyna Cholewinska
Daniel David
Stefan Kuetter
Zelalem Ternesgen
Timothy M Uyeki
H Clifford Lane
Jens Lundgren
James D Neaton
INSIGHT Influenza Study Group
author_facet Ruth Lynfield
Richard Davey
Dominic E Dwyer
Marcelo H Losso
Deborah Wentworth
Alessandro Cozzi-Lepri
Kathy Herman-Lamin
Grazyna Cholewinska
Daniel David
Stefan Kuetter
Zelalem Ternesgen
Timothy M Uyeki
H Clifford Lane
Jens Lundgren
James D Neaton
INSIGHT Influenza Study Group
author_sort Ruth Lynfield
collection DOAJ
description <h4>Background</h4>Data from prospectively planned cohort studies on risk of major clinical outcomes and prognostic factors for patients with influenza A(H1N1)pdm09 virus are limited. In 2009, in order to assess outcomes and evaluate risk factors for progression of illness, two cohort studies were initiated: FLU 002 in outpatients and FLU 003 in hospitalized patients.<h4>Methods and findings</h4>Between October 2009 and December 2012, adults with influenza-like illness (ILI) were enrolled; outpatients were followed for 14 days and inpatients for 60 days. Disease progression was defined as hospitalization and/or death for outpatients, and hospitalization for >28 days, transfer to intensive care unit (ICU) if enrolled from general ward, and/or death for inpatients. Infection was confirmed by RT-PCR. 590 FLU 002 and 392 FLU 003 patients with influenza A (H1N1)pdm09 were enrolled from 81 sites in 17 countries at 2 days (IQR 1-3) and 6 days (IQR 4-10) following ILI onset, respectively. Disease progression was experienced by 29 (1 death) outpatients (5.1%; 95% CI: 3.4-7.2%) and 80 inpatients [death (32), hospitalization >28 days (43) or ICU transfer (20)] (21.6%; 95% CI: 17.5-26.2%). Disease progression (death) for hospitalized patients was 53.1% (26.6%) and 12.8% (3.8%), respectively, for those enrolled in the ICU and general ward. In pooled analyses for both studies, predictors of disease progression were age, longer duration of symptoms at enrollment and immunosuppression. Patients hospitalized during the pandemic period had a poorer prognosis than in subsequent seasons.<h4>Conclusions</h4>Patients with influenza A(H1N1)pdm09, particularly when requiring hospital admission, are at high risk for disease progression, especially if they are older, immunodeficient, or admitted late in infection. These data reinforce the need for international trials of novel treatment strategies for influenza infection and serve as a reminder of the need to monitor the severity of seasonal and pandemic influenza epidemics globally.<h4>Trial registration</h4>ClinicalTrials.gov Identifiers: FLU 002--NCT01056354, FLU 003--NCT01056185.
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spelling doaj-art-dfcacd2a1b0a419d8a14af147d828a9e2025-08-20T02:34:07ZengPublic Library of Science (PLoS)PLoS ONE1932-62032014-01-0197e10178510.1371/journal.pone.0101785Outcomes of influenza A(H1N1)pdm09 virus infection: results from two international cohort studies.Ruth LynfieldRichard DaveyDominic E DwyerMarcelo H LossoDeborah WentworthAlessandro Cozzi-LepriKathy Herman-LaminGrazyna CholewinskaDaniel DavidStefan KuetterZelalem TernesgenTimothy M UyekiH Clifford LaneJens LundgrenJames D NeatonINSIGHT Influenza Study Group<h4>Background</h4>Data from prospectively planned cohort studies on risk of major clinical outcomes and prognostic factors for patients with influenza A(H1N1)pdm09 virus are limited. In 2009, in order to assess outcomes and evaluate risk factors for progression of illness, two cohort studies were initiated: FLU 002 in outpatients and FLU 003 in hospitalized patients.<h4>Methods and findings</h4>Between October 2009 and December 2012, adults with influenza-like illness (ILI) were enrolled; outpatients were followed for 14 days and inpatients for 60 days. Disease progression was defined as hospitalization and/or death for outpatients, and hospitalization for >28 days, transfer to intensive care unit (ICU) if enrolled from general ward, and/or death for inpatients. Infection was confirmed by RT-PCR. 590 FLU 002 and 392 FLU 003 patients with influenza A (H1N1)pdm09 were enrolled from 81 sites in 17 countries at 2 days (IQR 1-3) and 6 days (IQR 4-10) following ILI onset, respectively. Disease progression was experienced by 29 (1 death) outpatients (5.1%; 95% CI: 3.4-7.2%) and 80 inpatients [death (32), hospitalization >28 days (43) or ICU transfer (20)] (21.6%; 95% CI: 17.5-26.2%). Disease progression (death) for hospitalized patients was 53.1% (26.6%) and 12.8% (3.8%), respectively, for those enrolled in the ICU and general ward. In pooled analyses for both studies, predictors of disease progression were age, longer duration of symptoms at enrollment and immunosuppression. Patients hospitalized during the pandemic period had a poorer prognosis than in subsequent seasons.<h4>Conclusions</h4>Patients with influenza A(H1N1)pdm09, particularly when requiring hospital admission, are at high risk for disease progression, especially if they are older, immunodeficient, or admitted late in infection. These data reinforce the need for international trials of novel treatment strategies for influenza infection and serve as a reminder of the need to monitor the severity of seasonal and pandemic influenza epidemics globally.<h4>Trial registration</h4>ClinicalTrials.gov Identifiers: FLU 002--NCT01056354, FLU 003--NCT01056185.https://doi.org/10.1371/journal.pone.0101785
spellingShingle Ruth Lynfield
Richard Davey
Dominic E Dwyer
Marcelo H Losso
Deborah Wentworth
Alessandro Cozzi-Lepri
Kathy Herman-Lamin
Grazyna Cholewinska
Daniel David
Stefan Kuetter
Zelalem Ternesgen
Timothy M Uyeki
H Clifford Lane
Jens Lundgren
James D Neaton
INSIGHT Influenza Study Group
Outcomes of influenza A(H1N1)pdm09 virus infection: results from two international cohort studies.
PLoS ONE
title Outcomes of influenza A(H1N1)pdm09 virus infection: results from two international cohort studies.
title_full Outcomes of influenza A(H1N1)pdm09 virus infection: results from two international cohort studies.
title_fullStr Outcomes of influenza A(H1N1)pdm09 virus infection: results from two international cohort studies.
title_full_unstemmed Outcomes of influenza A(H1N1)pdm09 virus infection: results from two international cohort studies.
title_short Outcomes of influenza A(H1N1)pdm09 virus infection: results from two international cohort studies.
title_sort outcomes of influenza a h1n1 pdm09 virus infection results from two international cohort studies
url https://doi.org/10.1371/journal.pone.0101785
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