title: Patient-based and surgical characteristics associated with the acute development of deep venous thrombosis and pulmonary embolism after spine surgery.
abstract: METHODS
  Retrospective analysis of a prospectively collected data set.
  
  
  OBJECTIVE
  Identify the incidence of, and risk factors for, deep venous thrombosis (DVT) and pulmonary embolism (PE) after spine surgery.
  
  
  BACKGROUND
  Determination of ideal candidates for chemoprophylaxis after spine surgery is limited by the state of the literature, including incomplete understanding regarding the incidence of DVT and PE, as well as an inability to quantify specific risk factors among patients.
  
  
  METHODS
  The 2005 to 2011 data set of the National Surgical Quality Improvement Program was queried to identify all individuals having undergone spine surgery. Demographic data, medical comorbidities, surgical characteristics, and the presence of DVT, PE, and/or mortality were abstracted for all individuals meeting inclusion criteria. Unadjusted univariate analysis was performed to identify variables that were potentially associated with the development of DVT or PE after surgery. A multivariate logistic regression test, controlling for other factors present in the model, was subsequently performed. Predictor variables that maintained significance after multivariate testing were considered influential in the development of DVT and/or PE.
  
  
  RESULTS
  There were 27,730 patients who received spine procedures in this cohort. The average age was 56.4 (± 15.1) years. Lumbar spine procedures made up 61% of interventions. Death occurred in 87 instances (0.3%). The venous thromboembolic rate was 1%, with 206 individuals (0.7%) sustaining DVT and 113 (0.4%) developing a PE. Body mass index 40 and greater, age 80 years and older, operative time exceeding 261 minutes, and American Society of Anesthesiologists classification 3 or higher were identified as significant independent predictors of DVT, whereas body mass index 40 and greater, operative time exceeding 261 minutes, and male sex were associated with the development of PE.
  
  
  CONCLUSIONS
  Multiple independent risk factors for the development of DVT and/or PE after spine surgery were identified. Patients with these characteristics may require additional counseling, procedural modification, or prophylaxis against venous thromboembolic events.
authors.affiliation: *Department of Orthopaedic Surgery, William Beaumont Army Medical Center, Texas Tech University Health Sciences Center, El Paso, TX; and †Statistical Consulting Laboratory, University of Texas at El Paso, El Paso, TX.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Schoenfeld
authors.forename: Joshua P
authors.initials: JP
authors.lastname: Herzog
authors.forename: John C
authors.initials: JC
authors.lastname: Dunn
authors.forename: Julia O
authors.initials: JO
authors.lastname: Bader
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Belmont
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D019637:Orthopedic Procedures / Q000009:adverse effects* / Q000379:methods; D017063:Outcome Assessment, Health Care / Q000379:methods / Q000706:statistics & numerical data; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology*; D011655:Pulmonary Embolism / Q000453:epidemiology / Q000209:etiology*; D058996:Quality Improvement / Q000706:statistics & numerical data; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods / Q000706:statistics & numerical data; D012307:Risk Factors; D012737:Sex Factors; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D020246:Venous Thrombosis / Q000453:epidemiology / Q000209:etiology*