title: Viral pneumonitis is increased in obese patients during the first wave of pandemic A(H1N1) 2009 virus.
abstract: BACKGROUND
  There is conflicting data as to whether obesity is an independent risk factor for mortality in severe pandemic (H1N1) 2009 influenza (A(H1N1)pdm09). It is postulated that excess inflammation and cytokine production in obese patients following severe influenza infection leads to viral pneumonitis and/or acute respiratory distress syndrome.
  
  
  METHODS
  Demographic, laboratory and clinical data prospectively collected from obese and non-obese patients admitted to nine adult Australian intensive care units (ICU) during the first A(H1N1)pdm09 wave, supplemented with retrospectively collected data, were compared.
  
  
  RESULTS
  Of 173 patients, 100 (57.8%), 73 (42.2%) and 23 (13.3%) had body mass index (BMI) <30 kg/m(2), ≥30 kg/m(2) (obese) and ≥40 kg/m(2) (morbidly obese) respectively. Compared to non-obese patients, obese patients were younger (mean age 43.4 vs. 48.4 years, p = 0.035) and more likely to develop pneumonitis (61% vs. 44%, p = 0.029). Extracorporeal membrane oxygenation use was greater in morbidly obese compared to non-obese patients (17.4% vs. 4.7%, p = 0.04). Higher mortality rates were observed in non-obese compared to obese patients, but not after adjusting for severity of disease. C-reactive protein (CRP) levels and hospital length of stay (LOS) were similar. Amongst ICU survivors, obese patients had longer ICU LOS (median 11.9 vs. 6.8 days, p = 0.017). Similar trends were observed when only patients infected with A(H1N1)pdm09 were examined.
  
  
  CONCLUSIONS
  Among patients admitted to ICU during the first wave of A(H1N1)pdm09, obese and morbidly obese patients with severe infection were more likely to develop pneumonitis compared to non-obese patients, but mortality rates were not increased. CRP is not an accurate marker of pneumonitis.
authors: Centre for Infectious Diseases and Microbiology Laboratory Services, Institute of Clinical Pathology and Medical Research, Sydney Institute for Emerging Infections and Biosecurity, University of Sydney, Westmead Hospital, Westmead, New South Wales, Australia. jen.kok@swahs.health.nsw.gov.au
authors: Jen
authors: J
authors: Kok
authors: Christopher C
authors: CC
authors: Blyth
authors: Hong
authors: H
authors: Foo
authors: Michael J
authors: MJ
authors: Bailey
authors: David V
authors: DV
authors: Pilcher
authors: Steven A
authors: SA
authors: Webb
authors: Ian M
authors: IM
authors: Seppelt
authors: Dominic E
authors: DE
authors: Dwyer
authors: Jonathan R
authors: JR
authors: Iredell
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia; D002097:C-Reactive Protein; D003422:Critical Care; D015199:Extracorporeal Membrane Oxygenation; D005260:Female; D017052:Hospital Mortality; D006760:Hospitalization; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000150:complications* / Q000453:epidemiology; D007362:Intensive Care Units; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000453:epidemiology; D058873:Pandemics; D011024:Pneumonia, Viral / Q000453:epidemiology / Q000209:etiology*; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D002097:C-Reactive Protein