You are here

  • Home
  • Archive
  • Volume 1, Issue 1
  • Clinical and epidemiological profile of patients with severe H1N1/09 pandemic influenza in Australia and New Zealand: an observational cohort study

Article Text

Article menu
XML
Infectious diseases
Research
Clinical and epidemiological profile of patients with severe H1N1/09 pandemic influenza in Australia and New Zealand: an observational cohort study
  1. Allen C Cheng1,2,
  2. Tom Kotsimbos3,4,
  3. Anna Reynolds5,
  4. Simon D Bowler6,
  5. Simon G A Brown7,
  6. Robert J Hancox8,
  7. Mark Holmes9,10,
  8. Louis Irving11,12,
  9. Christine Jenkins13,
  10. Philip Thompson14,15,
  11. Graham Simpson16,
  12. Grant Waterer17,18,
  13. Richard Wood-Baker19,20,
  14. Paul M Kelly21
  1. 1Infectious Diseases Unit, The Alfred Hospital, Melbourne, Australia
  2. 2Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
  3. 3Department of Allergy, Immunology and Respiratory Medicine, The Alfred Hospital, Melbourne, Australia
  4. 4Department of Medicine, Monash University, Melbourne, Victoria, Australia
  5. 5Office of Health Protection, Australian Government Department of Health & Ageing, Canberra, Australian Capital Territory, Australia
  6. 6Department of Respiratory Medicine, Mater Adult Hospital, South Brisbane, Queensland, Australia
  7. 7Department of Emergency Medicine, Royal Perth Hospital, University of Western Australia, and Centre for Clinical Research in Emergency Medicine, Western Australian Institute for Medical Research, Perth, Western Australia, Australia
  8. 8Department for Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, Dunedin, Waikato Hospital, Hamilton, New Zealand
  9. 9The University of Adelaide, Adelaide, South Australia, Australia
  10. 10Department of Thoracic Medicine, Royal Adelaide Hospital, Chest Clinic, Adelaide, South Australia, Australia
  11. 11Department of Respiratory Medicine, Royal Melbourne Hospital, Melbourne, Australia
  12. 12Department of Medicine, University of Melbourne, Parkville, Melbourne, Australia
  13. 13Department of Respiratory Medicine, Concord Hospital, University of Sydney and Woolcock Institute of Medical Research, New South Wales, Australia
  14. 14Lung Institute of Western Australia and the Centre for Asthma, Allergy and Respiratory Research, University of Western Australia, Perth, Australia
  15. 15School of Medicine and Pharmacology, University of Western Australia, Western Australia, Australia
  16. 16Thoracic Medicine Department, Cairns Base Hospital, Cairns, Queensland, Australia
  17. 17Royal Perth Hospital, Perth, Western Australia, Australia
  18. 18School of Medicine and Pharmacology, University of Western Australia, Western Australia, Australia
  19. 19Department of Respiratory Medicine, Royal Hobart Hospital, Tasmania, Australia
  20. 20Respiratory Research Group, Menzies Research Institute, Hobart, Tasmania, Australia
  21. 21National Centre for Epidemiology & Population Health, College of Medicine, Biology & Environment, Australian National University, Canberra, Australian Capital Territory, Australia
  1. Correspondence to Dr Allen Cheng; allen.cheng{at}monash.edu

Abstract

Background Pandemic influenza H1N1/09 emerged in April 2009 and spread widely in Australia and New Zealand. Although an unprecedented number of cases required intensive care, comparative community-based studies with seasonal influenza strains have not shown any significant differences in clinical symptoms or severity.

Methods The authors performed active surveillance on confirmed influenza-related admissions and compared the clinical profile of patients with pandemic H1N1/09 influenza and patients with seasonal influenza at eight hospitals in Australia and one hospital in New Zealand.

Results During the 1 July and 30 November 2009, 560 patients with confirmed influenza were admitted, of which 478 had H1N1/09, and 82 had other seasonal strains. Patients with H1N1/09 influenza were younger, were more likely to have fever and were more likely to be pregnant but less likely to have chronic obstructive pulmonary disease and ischaemic heart disease than patients with seasonal strains. Other clinical features and comorbidities were reported in similar proportions. Admission to intensive care was required in 22% of patients with H1N1/09 influenza and 12% in patients with other strains. Hospital mortality was 5% in patients with H1N1 influenza.

Conclusions The clinical features of H1N1/09 influenza and seasonal strains were similar in hospitalised patients. A higher proportion of patients had comorbidities than had been reported in community-based studies. Although the overall mortality was similar, the authors found evidence that H1N1/09 caused severe disease in a higher proportion of hospitalised patients.

  • Infectious diseases
  • epidemiology
  • infection control
  • emergency medicine
  • toxinology
  • prehospital
  • evenoming
  • anaphylaxis
  • asthma
  • television
  • respiratory
  • patient reported outcomes airways disease
  • COPD

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: http://creativecommons.org/licenses/by-nc/2.0/ and http://creativecommons.org/licenses/by-nc/2.0/legalcode.

https://doi.org/10.1136/bmjopen-2011-000100

Statistics from Altmetric.com

    Request Permissions

    If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

    View Full Text

    Supplementary materials

    Footnotes

    • To cite: Cheng AC, Kotsimbos T, Reynolds A, et al. Clinical and epidemiological profile of patients with severe H1N1/09 pandemic influenza in Australia and New Zealand: an observational cohort study. BMJ Open 2011;1:e000100. doi:10.1136/bmjopen-2011-000100

    • Funding This project was supported by a NH&MRC strategic funding grant (585531). ACC was supported by a Health Professionals Research Fellowship. PMK is supported by a Career Development Award.

    • Competing interests AC is an investigator for a study of vaccine safety funded by CSL Ltd.

    • Ethics approval This study was conducted by approval of the Australian National University.

    • Contributors TK (chair), SDB, SGAB, RJH, MH, LI, CJ, PT, GS, GW and RW-B were all members of the Thoracic Society of Australia and New Zealand Swine Flu task force who supervised the data collection at each site. They designed the study in conjunction with PMK, AR and ACC, and the group obtained funding to perform the study. ACC analysed the data and drafted the manuscript. All authors assisted with the interpretation of findings and revised the manuscript.

    • Provenance and peer review Not commissioned; externally peer reviewed.