title: The effects of body mass index on complications and mortality after emergency abdominal operations: The obesity paradox.
abstract: BACKGROUND
  Recent literature suggests that obesity is protective in critically illness. This study addresses the effect of BMI on outcomes after emergency abdominal surgery (EAS).
  
  
  METHODS
  Retrospective, ACS-NSQIP analysis. All patients that underwent EAS were included. The study population was divided into five groups based on BMI; regression models were used to evaluate the role of obesity in morbidity and mortality.
  
  
  RESULTS
  101,078 patients underwent EAS; morbidity and mortality were 19.5% and 4.5%, respectively. Adjusted mortality was higher in underweight patients (AOR 1.92), but significantly lower in all obesity groups (AOR's 0.73, 0.66, 0.70, 0.70 respectively). Underweight and class III obesity was associated with increased complications (AOR 1.47 and 1.30), while mild obesity was protective (AOR 0.92).
  
  
  CONCLUSIONS
  Underweight patients undergoing EAS have increased morbidity and mortality. Although class III obesity is associated with increased morbidity, overweight and class I obesity were protective. All grades of obesity may be protective against mortality after EAS relative to normal weight patients.
authors.affiliation: Department of Surgery, Division of Acute Care Surgery and Surgical Critical Care, Los Angeles County and University of Southern California Medical Center, Los Angeles, CA, USA. Electronic address: Elizabeth.Benjamin@med.usc.edu.
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Benjamin
authors.affiliation: Department of Surgery, Division of Acute Care Surgery and Surgical Critical Care, Los Angeles County and University of Southern California Medical Center, Los Angeles, CA, USA.
authors.forename: Evren
authors.initials: E
authors.lastname: Dilektasli
authors.affiliation: Department of Surgery, Division of Acute Care Surgery and Surgical Critical Care, Los Angeles County and University of Southern California Medical Center, Los Angeles, CA, USA.
authors.forename: Tobias
authors.initials: T
authors.lastname: Haltmeier
authors.affiliation: Department of Surgery, Division of Acute Care Surgery and Surgical Critical Care, Los Angeles County and University of Southern California Medical Center, Los Angeles, CA, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Beale
authors.affiliation: Department of Surgery, Division of Acute Care Surgery and Surgical Critical Care, Los Angeles County and University of Southern California Medical Center, Los Angeles, CA, USA.
authors.forename: Kenji
authors.initials: K
authors.lastname: Inaba
authors.affiliation: Department of Surgery, Division of Acute Care Surgery and Surgical Critical Care, Los Angeles County and University of Southern California Medical Center, Los Angeles, CA, USA.
authors.forename: Demetrios
authors.initials: D
authors.lastname: Demetriades
mesh_terms: D000005:Abdomen / Q000601:surgery*; D015992:Body Mass Index; D004638:Emergency Treatment; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000145:classification / Q000150:complications*; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology* / Q000401:mortality; D012189:Retrospective Studies; D013851:Thinness / Q000150:complications*
keywords: Body mass index; Emergency abdominal surgery; Obesity