Header

UZH-Logo

Maintenance Infos

Populations at risk for severe or complicated influenza illness: systematic review and meta-analysis


Mertz, Dominik; Kim, Tae Hyong; Johnstone, Jennie; Lam, Po-Po; Science, Michelle; Kuster, Stefan P; Fadel, Shaza A; Tran, Dat; Fernandez, Eduardo; Bhatnagar, Neera; Loeb, Mark (2013). Populations at risk for severe or complicated influenza illness: systematic review and meta-analysis. British Medical Journal, 347:f5061.

Abstract

OBJECTIVE: To evaluate risk factors for severe outcomes in patients with seasonal and pandemic influenza.
DESIGN: Systematic review.
STUDY SELECTION: Observational studies reporting on risk factor-outcome combinations of interest in participants with influenza. Outcomes included death, ventilator support, admission to hospital, admission to an intensive care unit, pneumonia, and composite outcomes.
DATA SOURCES: Medline, Embase, CINAHL, Global Health, and the Cochrane Central Register of Controlled Trials to March 2011.
RISK OF BIAS ASSESSMENT: Newcastle-Ottawa scale to assess the risk of bias. GRADE framework to evaluate the quality of evidence.
RESULTS: 63 537 articles were identified of which 234 with a total of 610 782 participants met the inclusion criteria. The evidence supporting risk factors for severe outcomes of influenza ranged from being limited to absent. This was particularly relevant for the relative lack of data for non-2009 H1N1 pandemics and for seasonal influenza studies. Limitations in the published literature included lack of power and lack of adjustment for confounders was widespread: adjusted risk estimates were provided for only 5% of risk factor-outcome comparisons in 39 of 260 (15%) studies. The level of evidence was low for "any risk factor" (odds ratio for mortality 2.77, 95% confidence interval 1.90 to 4.05 for pandemic influenza and 2.04, 1.74 to 2.39 for seasonal influenza), obesity (2.74, 1.56 to 4.80 and 30.1, 1.74 to 2.39), cardiovascular diseases (2.92, 1.76 to 4.86 and 1.97, 1.06 to 3.67), and neuromuscular disease (2.68, 1.91 to 3.75 and 3.21, 1.84 to 5.58). The level of evidence was very low for all other risk factors. Some well accepted risk factors such as pregnancy and belonging to an ethnic minority group could not be identified as risk factors. In contrast, women who were less than four weeks post partum had a significantly increased risk of death from pandemic influenza (4.43, 1.24 to 15.81).
CONCLUSION: The level of evidence to support risk factors for influenza related complications is low and some well accepted risk factors, including pregnancy and ethnicity, could not be confirmed as risks. Rigorous and adequately powered studies are needed.

Abstract

OBJECTIVE: To evaluate risk factors for severe outcomes in patients with seasonal and pandemic influenza.
DESIGN: Systematic review.
STUDY SELECTION: Observational studies reporting on risk factor-outcome combinations of interest in participants with influenza. Outcomes included death, ventilator support, admission to hospital, admission to an intensive care unit, pneumonia, and composite outcomes.
DATA SOURCES: Medline, Embase, CINAHL, Global Health, and the Cochrane Central Register of Controlled Trials to March 2011.
RISK OF BIAS ASSESSMENT: Newcastle-Ottawa scale to assess the risk of bias. GRADE framework to evaluate the quality of evidence.
RESULTS: 63 537 articles were identified of which 234 with a total of 610 782 participants met the inclusion criteria. The evidence supporting risk factors for severe outcomes of influenza ranged from being limited to absent. This was particularly relevant for the relative lack of data for non-2009 H1N1 pandemics and for seasonal influenza studies. Limitations in the published literature included lack of power and lack of adjustment for confounders was widespread: adjusted risk estimates were provided for only 5% of risk factor-outcome comparisons in 39 of 260 (15%) studies. The level of evidence was low for "any risk factor" (odds ratio for mortality 2.77, 95% confidence interval 1.90 to 4.05 for pandemic influenza and 2.04, 1.74 to 2.39 for seasonal influenza), obesity (2.74, 1.56 to 4.80 and 30.1, 1.74 to 2.39), cardiovascular diseases (2.92, 1.76 to 4.86 and 1.97, 1.06 to 3.67), and neuromuscular disease (2.68, 1.91 to 3.75 and 3.21, 1.84 to 5.58). The level of evidence was very low for all other risk factors. Some well accepted risk factors such as pregnancy and belonging to an ethnic minority group could not be identified as risk factors. In contrast, women who were less than four weeks post partum had a significantly increased risk of death from pandemic influenza (4.43, 1.24 to 15.81).
CONCLUSION: The level of evidence to support risk factors for influenza related complications is low and some well accepted risk factors, including pregnancy and ethnicity, could not be confirmed as risks. Rigorous and adequately powered studies are needed.

Statistics

Citations

92 citations in Web of Science®
111 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

46 downloads since deposited on 14 Jan 2014
14 downloads since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Infectious Diseases
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2013
Deposited On:14 Jan 2014 09:43
Last Modified:09 Aug 2017 01:39
Publisher:BMJ Publishing Group
ISSN:0959-535X
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.1136/bmj.f5061
PubMed ID:23974637

Download

Preview Icon on Download
Preview
Content: Published Version
Filetype: PDF
Size: 591kB
View at publisher

TrendTerms

TrendTerms displays relevant terms of the abstract of this publication and related documents on a map. The terms and their relations were extracted from ZORA using word statistics. Their timelines are taken from ZORA as well. The bubble size of a term is proportional to the number of documents where the term occurs. Red, orange, yellow and green colors are used for terms that occur in the current document; red indicates high interlinkedness of a term with other terms, orange, yellow and green decreasing interlinkedness. Blue is used for terms that have a relation with the terms in this document, but occur in other documents.
You can navigate and zoom the map. Mouse-hovering a term displays its timeline, clicking it yields the associated documents.

Author Collaborations