title: Epidemiology of Australian Influenza-Related Paediatric Intensive Care Unit Admissions, 1997-2013.
abstract: BACKGROUND
  Influenza virus predictably causes an annual epidemic resulting in a considerable burden of illness in Australia. Children are disproportionately affected and can experience severe illness and complications, which occasionally result in death.
  
  
  METHODS
  We conducted a retrospective descriptive study using data collated in the Australian and New Zealand Paediatric Intensive Care (ANZPIC) Registry of influenza-related intensive care unit (ICU) admissions over a 17-year period (1997-2013, inclusive) in children <16 years old. National laboratory-confirmed influenza notifications were used for comparison.
  
  
  RESULTS
  Between 1997 and 2013, a total of 704 influenza-related ICU admissions were recorded, at a rate of 6.2 per 1,000 all-cause ICU admissions. Age at admission ranged from 0 days and 15.9 years (median = 2.1 years), with 135 (19.2%) aged <6 months. Pneumonia/pneumonitis and bronchiolitis were the most common primary diagnoses among influenza-related admissions (21.9% and 13.6%, respectively). More than half of total cases (59.2%) were previously healthy (no co-morbidities recorded), and in the remainder, chronic lung disease (16.7%) and asthma (12.5%) were the most common co-morbidities recorded. Pathogen co-detection occurred in 24.7% of cases, most commonly with respiratory syncytial virus or a staphylococcal species. Median length of all ICU admissions was 3.2 days (range 2.0 hours- 107.4 days) and 361 (51.3%) admissions required invasive respiratory support for a median duration of 4.3 days (range 0.2 hours- 107.5 days). There were 27 deaths recorded, 14 (51.9%) in children without a recorded co-morbidity.
  
  
  CONCLUSIONS
  Influenza causes a substantial number of ICU admissions in Australian children each year with the majority occurring in previously healthy children.
authors.affiliation: Child Health Research Centre, School of Medicine, The University of Queensland, Brisbane, Australia.|The University of Queensland, School of Public Health, Brisbane, Australia.|Queensland Children's Medical Research Institute, Brisbane, Australia.
authors.forename: Marlena C
authors.initials: MC
authors.lastname: Kaczmarek
authors.affiliation: Child Health Research Centre, School of Medicine, The University of Queensland, Brisbane, Australia.|The University of Queensland, School of Public Health, Brisbane, Australia.|Queensland Children's Medical Research Institute, Brisbane, Australia.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Ware
authors.affiliation: Paediatric Intensive Care Unit, Lady Cilento Children's Hospital, Brisbane, Australia.|Academic Discipline of Paediatrics and Child Health, School of Medicine, The University of Queensland, Brisbane, Australia.
authors.forename: Mark G
authors.initials: MG
authors.lastname: Coulthard
authors.affiliation: Paediatric Intensive Care Unit, Lady Cilento Children's Hospital, Brisbane, Australia.
authors.forename: Julie
authors.initials: J
authors.lastname: McEniery
authors.affiliation: Child Health Research Centre, School of Medicine, The University of Queensland, Brisbane, Australia.|Queensland Children's Medical Research Institute, Brisbane, Australia.|Communicable Diseases Unit, Queensland Health, Brisbane, Australia.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Lambert
mesh_terms: D000293:Adolescent; D001315:Australia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D003710:Demography; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007251:Influenza, Human / Q000453:epidemiology*; D015278:Intensive Care Units, Pediatric / Q000706:statistics & numerical data*; D008297:Male; D010343:Patient Admission / Q000706:statistics & numerical data*