title: Obese patients undergoing cystectomy: a population-based, propensity score matched analysis.
abstract: OBJECTIVE
  To examine the impact of body mass index, as a measure of obesity, on the surgical outcomes of cystectomy.
  
  
  METHODS
  The American College of Surgeons National Surgical Quality Improvement Program database was used to acquire data on 1293 cystectomies carried out from 2005 to 2011. Patients were divided into two groups: body mass index <30 kg/m(2) and ≥30 kg/m(2). A propensity score-matched analysis of perioperative outcomes was carried out.
  
  
  RESULTS
  A total of 869 patients had a body mass index <30, whereas 424 had a body mass index ≥30. Unadjusted comparisons showed higher rates of superficial surgical site infections (8.7% vs 5.3%, P = 0.04), renal insufficiency (4.0% vs 1.7%, P = 0.01) and increased operative times (365.7 min vs 338.6 min, P = 0.0004) in the obese patients, but interestingly lower rates of pneumonia (2.4% vs 4.8, P = 0.03) and cerebral vascular accidents (0.0% vs 0.9%, P = 0.05). However, the latter two observations might be explained by more tobacco use among non-obese patients (26.6 mean pack-years vs 20.0 mean pack-years, P = 0.004). Notably, no differences in 30-day mortality were noted. After adjusting for preoperative demographic and clinical data using propensity score-matching methods, there were no observed differences between the two cohorts except for operative time (P = 0.04).
  
  
  CONCLUSIONS
  Obesity is not independently associated with an increased risk of perioperative complications or 30-day mortality after cystectomy.
authors.affiliation: Department of Urology, Mayo Clinic, Phoenix, Arizona, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Tyson
authors.forename: Mitchell R
authors.initials: MR
authors.lastname: Humphreys
authors.forename: Erik P
authors.initials: EP
authors.lastname: Castle
mesh_terms: D000368:Aged; D015992:Body Mass Index; D015653:Cystectomy; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000150:complications*; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology*; D057216:Propensity Score; D018570:Risk Assessment; D016896:Treatment Outcome
keywords: cystectomy; mortality; obesity; propensity score; surgical outcomes