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Cited by 30Influenza Virus Research StudiesPneumonia and Respiratory InfectionsRespiratory viral infections research

Severity of Influenza A 2009 (H1N1) Pneumonia Is Underestimated by Routine Prediction Rules. Results from a Prospective, Population-Based Study

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Bjarnason, Agnar, Thorleifsdottir, Gudlaug, Löve, Arthur, Gudnason, Janus F., Asgeirsson, Hilmir, Hallgrimsson, Kristinn L., Kristjansdottir, Berglind S., Haraldsson, Gunnsteinn +3 more·2012·PLoS ONE
DOI 10.1371/journal.pone.0046816PMC PMC3469650
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Abstract

BACKGROUND: Characteristics of patients with community-acquired pneumonia (CAP) due to pandemic influenza A 2009 (H1N1) have been inadequately compared to CAP caused by other respiratory pathogens. The performance of prediction rules for CAP during an epidemic with a new infectious agent are unknown. METHODS: Prospective, population-based study from November 2008-November 2009, in centers representing 70% of hospital beds in Iceland. Patients admitted with CAP underwent evaluation and etiologic testing, including polymerase chain reaction (PCR) for influenza. Data on influenza-like illness in the community and overall hospital admissions were collected. Clinical and laboratory data, including pneumonia severity index (PSI) and CURB-65 of patients with CAP due to H1N1 were compared to those caused by other agents. RESULTS: Of 338 consecutive and eligible patients 313 (93%) were enrolled. During the pandemic peak, influenza A 2009 (H1N1) patients constituted 38% of admissions due to CAP. These patients were younger, more dyspnoeic and more frequently reported hemoptysis. They had significantly lower severity scores than other patients with CAP (1.23 vs. 1.61, P= .02 for CURB-65, 2.05 vs. 2.87 for PSI, P<.001) and were more likely to require intensive care admission (41% vs. 5%, P<.001) and receive mechanical ventilation (14% vs. 2%, P= .01). Bacterial co-infection was detected in 23% of influenza A 2009 (H1N1) patients with CAP. CONCLUSIONS: Clinical characteristics of CAP caused by influenza A 2009 (H1N1) differ markedly from CAP caused by other etiologic agents. Commonly used CAP prediction rules often failed to predict admissions to intensive care or need for assisted ventilation in CAP caused by the influenza A 2009 (H1N1) virus, underscoring the importance of clinical acumen under these circumstances.

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  • An additional six studies reported that 12-50% of patients had preceding antibiotic treatment at enrollment.

    “An additional six studies reported on participant antibiotic use at the time of enrollment and found that 12–50% of patients had preceding antibiotic treatment which may have led to an underestimation of the true frequency of bacterial coinfection in their sample population.30, 33, 40, 45, 47, 52”

    From The frequency of influenza and bacterial coinfection: a systematic review and meta-analysis. (2016) · cites this paper as [30]

  • Preceding antibiotic treatment may have led to an underestimation of the true frequency of bacterial coinfection in the sample population.

    “An additional six studies reported on participant antibiotic use at the time of enrollment and found that 12–50% of patients had preceding antibiotic treatment which may have led to an underestimation of the true frequency of bacterial coinfection in their sample population.30, 33, 40, 45, 47, 52”

    From The frequency of influenza and bacterial coinfection: a systematic review and meta-analysis. (2016) · cites this paper as [30]

  • Bjarnason and colleagues found that none of the patients using antibiotics were in the coinfected group and when they excluded antibiotic users, the prevalence of coinfection increased from 14% to 45%.

    “For example, Bjarnason and colleagues found that none of the patients using antibiotics were in the coinfected group and when they excluded antibiotic users from the study, the prevalence of coinfection increased from 14% to 45%.30”

    From The frequency of influenza and bacterial coinfection: a systematic review and meta-analysis. (2016) · cites this paper as [30]

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Authors
Bjarnason, A., Thorleifsdottir, G., Löve, A., Gudnason, J. F., Asgeirsson, H., Hallgrimsson, K. L., Kristjansdottir, B. S., Haraldsson, G., Baldursson, O., Kristinsson, K. G., & Gottfredsson, M.
Affiliations
  • University of Iceland (IS)
  • National University Hospital of Iceland (IS)
ORCID
Venue
PLoS ONE
Publisher
Public Library of Science (PLoS)
Published
2012-10-11
Volume
7
Issue
10
Pages
e46816
ISSN
1932-6203 (ISSN-L)
DOI
10.1371/journal.pone.0046816
PMC
PMC3469650
OpenAlex
W2079479516
Cited by
30
References
41
Citations by year
2026: 1 · 2025: 1 · 2024: 1 · 2023: 2 · 2022: 4 · 2021: 3 · 2020: 2 · 2019: 3 · 2018: 1 · 2017: 2 · 2016: 1 · 2015: 5 · 2014: 2 · 2013: 2
FWCI
2.15
Type
journal article
Language
en
Open access
Licence
Locations
  • PLoS ONE (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Hirsla (Landspítali University Hospital) (submittedVersion)
Funders
Landspítali Háskólasjúkrahús
Topics
  • Health Sciences › Medicine › Epidemiology › Influenza Virus Research Studies
  • Health Sciences › Medicine › Epidemiology › Pneumonia and Respiratory Infections
  • Health Sciences › Medicine › Epidemiology › Respiratory viral infections research
Keywords
2009 H1N1 pandemic, community-acquired pneumonia, pneumonia severity, prediction rules, CURB-65, Pneumonia Severity Index, intensive care unit admission, mechanical ventilation, bacterial co-infection, influenza-like illness, clinical features
MeSH terms
Adult, Aged, Anti-Bacterial Agents, Antiviral Agents, Female, Humans, Iceland, Influenza, Human, Intensive Care Units, Length of Stay, Male, Middle Aged, Mycoplasma pneumoniae, Patient Admission, Prospective Studies, Severity of Illness Index, Streptococcus pneumoniae, Comorbidity, Community-Acquired Infections, Pneumonia, Bacterial, Influenza A Virus, H1N1 Subtype, Oseltamivir, Pandemics, Coinfection

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