title: Obesity Increases Risk-Adjusted Morbidity, Mortality, and Cost Following Cardiac Surgery.
abstract: BACKGROUND
  Despite the epidemic rise in obesity, few studies have evaluated the effect of obesity on cost following cardiac surgery. We hypothesized that increasing body mass index (BMI) is associated with worse risk-adjusted outcomes and higher cost.
  
  
  RESULTS
  Medical records for 13 637 consecutive patients who underwent coronary artery bypass grafting (9702), aortic (1535) or mitral (837) valve surgery, and combined valve-coronary artery bypass grafting (1663) procedures were extracted from a regional Society of Thoracic Surgeons certified database. Patients were stratified by BMI: normal to overweight (BMI 18.5-30), obese (BMI 30-40), and morbidly obese (BMI >40). Differences in outcomes and cost were compared between BMI strata and also modeled as a continuous function of BMI with adjustment for preoperative risk using Society of Thoracic Surgeons predictive risk indices. Morbidly obese patients incurred nearly 60% greater observed mortality than normal weight patients. Moreover, morbidly obese patients had greater than 2-fold increase in renal failure and 6.5-fold increase in deep sternal wound infection. After risk adjustment, a significant association was found between BMI and mortality (P<0.001) and major morbidity (P<0.001). The risk-adjusted odds ratio for mortality for morbidly obese patients was 1.57 (P=0.02) compared to normal patients. Importantly, risk-adjusted total hospital cost increased with BMI, with 17.2% higher costs in morbidly obese patients.
  
  
  CONCLUSIONS
  Higher BMI is associated with increased mortality, major morbidity, and cost for hospital care. As such, BMI should be more strongly considered in risk assessment and resource allocation.
authors.affiliation: Baylor College of Medicine, Houston, TX ghanta@bcm.edu.
authors.forename: Ravi K
authors.initials: RK
authors.lastname: Ghanta
authors.affiliation: University of Virginia, Charlottesville, VA.
authors.forename: Damien J
authors.initials: DJ
authors.lastname: LaPar
authors.affiliation: Baylor College of Medicine, Houston, TX.
authors.forename: Qianzi
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: University of Virginia, Charlottesville, VA.
authors.forename: Vishal
authors.initials: V
authors.lastname: Devarkonda
authors.affiliation: University of Virginia, Charlottesville, VA.
authors.forename: James M
authors.initials: JM
authors.lastname: Isbell
authors.affiliation: University of Virginia, Charlottesville, VA.
authors.forename: Leora T
authors.initials: LT
authors.lastname: Yarboro
authors.affiliation: University of Virginia, Charlottesville, VA.
authors.forename: John A
authors.initials: JA
authors.lastname: Kern
authors.affiliation: University of Virginia, Charlottesville, VA.
authors.forename: Irving L
authors.initials: IL
authors.lastname: Kron
authors.affiliation: Inova Heart and Vascular Institute, Falls Church, VA.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Speir
authors.affiliation: Virginia Cardiac Surgery Quality Initiative, Charlottesville, VA.
authors.forename: Clifford E
authors.initials: CE
authors.lastname: Fonner
authors.affiliation: University of Virginia, Charlottesville, VA.
authors.forename: Gorav
authors.initials: G
authors.lastname: Ailawadi
mesh_terms: D000368:Aged; D001021:Aortic Valve / Q000601:surgery; D006348:Cardiac Surgical Procedures; D001026:Coronary Artery Bypass; D005260:Female; D017048:Health Care Costs; D019918:Heart Valve Prosthesis Implantation; D006760:Hospitalization / Q000191:economics; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000601:surgery; D009026:Mortality; D055361:Multilevel Analysis; D009765:Obesity / Q000453:epidemiology*; D009767:Obesity, Morbid / Q000453:epidemiology; D016017:Odds Ratio; D050177:Overweight / Q000453:epidemiology; D011183:Postoperative Complications / Q000191:economics / Q000453:epidemiology*
keywords: complication; cost; obesity; surgery