title: Impact of Body Mass Index on Outcomes in Cardiac Surgery.
abstract: OBJECTIVE
  Body mass index (BMI) commonly is used in obesity classification as a surrogate measure, and obesity is associated with a cluster of risk factors for cardiovascular disease. The aim of this study was to investigate the impact of BMI on short-term outcomes after cardiac surgery.
  
  
  METHODS
  A retrospective cohort study.
  
  
  METHODS
  University teaching hospital, 2 centers.
  
  
  METHODS
  The study comprised 4,740 patients who underwent cardiac surgery at 2 hospitals-from July 1, 2001, to June 30, 2013, in 1 hospital and from September 1, 2003, to August 31, 2014, in a second hospital.
  
  
  METHODS
  No changes to standard practice were required.
  
  
  RESULTS
  Patients were assigned into 6 BMI groups as follows: underweight (BMI<18.5 kg/m(2)), normal weight (≥18.5 to<25 kg/m(2)), overweight (≥25 to<30 kg/m(2)), class I obese (≥30 to<35 kg/m(2)), class II obese (≥35 to<40 kg/m(2)), and class III obese (BMI≥40 kg/m(2)). Short-term major postoperative complications (postoperative stroke, cardiac arrest, new atrial fibrillation/flutter, permanent rhythm device insertion, deep sternal infection, sepsis, prolonged ventilation, pneumonia, renal dialysis, renal failure, intensive care unit readmission, total intensive care unit hours, and readmission in 30 days, and mortalities (in-hospital mortality, 30-day mortality, surgical mortality) were compared among various BMI groups after cardiac surgery. Age, sex, surgery type, family history of coronary artery disease, diabetes, hypertension, heart failure, and lipid-lowering medication were the risk factors for early outcomes. Multiple logistic regression analysis indicated that the underweight and class III obese BMI groups demonstrated significant, adverse differences in some short-term outcomes, including deep sternal infection, prolonged ventilation, new atrial fibrillation/flutter, and renal failure. However, being in the overweight or class I obese group demonstrated a positive effect on discharge and surgical mortality.
  
  
  CONCLUSIONS
  The results of this study demonstrated that extreme obesity and underweight were significantly associated with early major adverse clinical outcomes. However, there was an "obese paradox" in short-term mortality after cardiac surgery.
authors.affiliation: Department of Anesthesiology, First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China; Department of Anesthesiology and Pain Medicine, University of California Davis Health System, Sacramento, CA.
authors.forename: Mei
authors.initials: M
authors.lastname: Gao
authors.affiliation: Department of Anesthesiology, Thomas Jefferson University and Hospitals, Philadelphia, PA.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Sun
authors.affiliation: Departments of §Surgery and.
authors.forename: Nilas
authors.initials: N
authors.lastname: Young
authors.affiliation: Departments of §Surgery and.
authors.forename: Douglas
authors.initials: D
authors.lastname: Boyd
authors.affiliation: Departments of §Surgery and.
authors.forename: Zane
authors.initials: Z
authors.lastname: Atkins
authors.affiliation: Internal Medicine, University of California Davis Health System, Sacramento, CA.
authors.forename: Zhongmin
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Anesthesiology, Thomas Jefferson University and Hospitals, Philadelphia, PA; Department of Anesthesiology, The Fourth Military Medical University, Xian, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Ding
authors.affiliation: Division of Cardiothoracic Surgery, Thomas Jefferson University and Hospitals, Philadelphia, PA.
authors.forename: James
authors.initials: J
authors.lastname: Diehl
authors.affiliation: Department of Anesthesiology, Thomas Jefferson University and Hospitals, Philadelphia, PA. Electronic address: hualiu@ucdavis.edu.
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
mesh_terms: D015992:Body Mass Index; D006348:Cardiac Surgical Procedures; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D011183:Postoperative Complications; D012189:Retrospective Studies; D013851:Thinness / Q000150:complications*; D016896:Treatment Outcome
keywords: body mass index; cardiac surgery; mortality; obese; outcome