title: Prevalence of obesity and the effect on length of mechanical ventilation and length of stay in intensive care patients: A single site observational study.
abstract: OBJECTIVE
  To provide a snapshot of the prevalence of abnormal body mass index (BMI) in a sample of intensive care unit (ICU) patients; to identify if any medical specialty was associated with abnormal BMI and to explore associations between BMI and ICU-related outcomes.
  
  
  BACKGROUND
  Obesity is an escalating public health issue across developed nations but there is little data pertaining to critically ill patients who require care that is expensive.
  
  
  METHODS
  Retrospective observational audit of 735 adult patients (median age 58 years) admitted to the Sir Charles Gairdner Hospital 23 bed tertiary ICU between November 2012 and June 2014. Primary outcome measure was patient BMI: underweight (<18.5kg/m2), normal weight (18.5-24.99kg/m2), overweight (25-29.99kg/m2), obese (30-39.99kg/m2) or extreme obese (40kg/m2or above). Other measures included gender, acute physiology and chronic health evaluation II score, admission specialty, length of mechanical ventilation (MV), length of stay (LOS) and mortality.
  
  
  RESULTS
  Compared to the general population there was a higher proportion of obese patients within the cohort with the majority of patients overweight (33.9%) or obese (36.5%) and median BMI of 27.9 (IQR 7.9). There were no significant differences between specialties for BMI (p=0.103) and abnormal BMI was not found to impact negatively on mortality (ICU, p=0.373; hospital, p=0.330). Normal BMI patients had shorter length of MV than other BMI categories and the impact of BMI on ICU LOS was dependent on length of MV. Overweight patients ventilated for five days or more had a shorter LOS, and extremely obese non-ventilated patients had a longer LOS, compared to normal weight patients.
  
  
  CONCLUSIONS
  Although the obesity-disease relationship is increasingly complex and data presented reflects categorical BMI for patients admitted to a single ICU site it may be important to consider the cost implications of caring for this cohort especially with regard to MV and LOS.
authors: Sir Charles Gairdner Hospital, Intensive Care Unit, Hospital Ave., Nedlands, WA 6009, Australia. Electronic address: Diane.Dennis@health.wa.gov.au.
authors: Diane M
authors: DM
authors: Dennis
authors: University of Western Australia, Centre for Applied Statistics, Stirling Highway, Crawley, WA 6009, Australia; Sir Charles Gairdner Hospital, Department of Research, Hospital Ave., Nedlands, WA 6009, Australia.
authors: Chrianna
authors: C
authors: Bharat
authors: Sir Charles Gairdner Hospital, Intensive Care Unit, Hospital Ave., Nedlands, WA 6009, Australia.
authors: Timothy
authors: T
authors: Paterson
mesh_terms: D018806:APACHE; D015992:Body Mass Index; D016638:Critical Illness; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D007902:Length of Stay / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology*; D015995:Prevalence; D012121:Respiration, Artificial / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D014904:Western Australia / Q000453:epidemiology
keywords: Body mass index; Critical care; Length of stay; Obesity