title: Surgical duration and risk of venous thromboembolism.
abstract: OBJECTIVE
  There is a paucity of data assessing the effect of increased surgical duration on the incidence of venous thromboembolism (VTE).
  
  
  OBJECTIVE
  To examine the association between surgical duration and the incidence of VTE.
  
  
  METHODS
  Retrospective cohort of 1,432,855 patients undergoing surgery under general anesthesia at 315 US hospitals participating in the American College of Surgeons National Surgical Quality Improvement Program from 2005 to 2011.
  
  
  METHODS
  Duration of surgery.
  
  
  METHODS
  The rates of deep vein thrombosis (DVT), pulmonary embolism (PE), and VTE within 30 days of the index operation. Surgical duration was standardized across Current Procedural Terminology codes using a z score. Outcomes were compared across quintiles of the z score. Multiple logistic regression models were developed to examine the association while adjusting for patient demographics, clinical characteristics, and comorbidities.
  
  
  RESULTS
  The overall VTE rate was 0.96% (n = 13,809); the rates of DVT and PE were 0.71% (n = 10,198) and 0.33% (n = 4772), respectively. The association between surgical duration and VTE increased in a stepwise fashion. Compared with a procedure of average duration, patients undergoing the longest procedures experienced a 1.27-fold (95% CI, 1.21-1.34; adjusted risk difference [ARD], 0.23%) increase in the odds of developing a VTE; the shortest procedures demonstrated an odds ratio of 0.86 (95% CI, 0.83-0.88; ARD, -0.12%). The robustness of these results was substantiated with several sensitivity analyses attempting to minimize the effect of outliers, concurrent complications, procedural differences, and unmeasured confounding variables.
  
  
  CONCLUSIONS
  Among patients undergoing surgery, an increase in surgical duration was directly associated with an increase in the risk for VTE. These findings may help inform preoperative and postoperative decision making related to surgery.
authors.affiliation: Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
authors.forename: John Y S
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
authors.forename: Nima
authors.initials: N
authors.lastname: Khavanin
authors.affiliation: Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
authors.forename: Aksharananda
authors.initials: A
authors.lastname: Rambachan
authors.affiliation: Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: McCarthy
authors.affiliation: Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
authors.forename: Alexei S
authors.initials: AS
authors.lastname: Mlodinow
authors.affiliation: Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
authors.forename: Gildasio S
authors.initials: GS
authors.lastname: De Oliveria
authors.affiliation: Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
authors.forename: M Christine
authors.initials: MC
authors.lastname: Stock
authors.affiliation: Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
authors.forename: Madeleine J
authors.initials: MJ
authors.lastname: Gust
authors.affiliation: Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
authors.forename: David M
authors.initials: DM
authors.lastname: Mahvi
mesh_terms: D000328:Adult; D000368:Aged; D016208:Databases, Factual; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D011183:Postoperative Complications; D011655:Pulmonary Embolism / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D014481:United States; D054556:Venous Thromboembolism / Q000453:epidemiology*; D020246:Venous Thrombosis / Q000453:epidemiology*