title: The prevalence of and specific risk factors for venous thromboembolic disease following elective spine surgery.
abstract: BACKGROUND
  Venous thromboembolic disease, including deep venous thrombosis and pulmonary embolism, is a serious and potentially life-threatening complication following orthopaedic surgical procedures. We sought to investigate the prevalence of thromboembolism as well as the efficacy and complications of various prophylactic measures in a population of patients who had undergone elective spine surgery.
  
  
  METHODS
  A meta-analysis and univariate logistic regression were performed on selected studies to determine the prevalence of and risk factors for deep venous thrombosis and pulmonary embolism following elective spine surgery. Studies were included on the basis of the selection criteria (specifically, the inclusion of only patients undergoing spine surgery, or the treatment of patients undergoing spine surgery as an independent cohort; the use of an objective diagnostic modality for the diagnosis of deep venous thrombosis, including Doppler ultrasonography or venography; the use of an objective diagnostic modality for the diagnosis of pulmonary embolism, including computed tomography of the chest or a ventilation-perfusion scan; and a study population of more than thirty patients). Patients with a known spinal cord injury were excluded.
  
  
  RESULTS
  Fourteen studies (including a total of 4383 patients) met our selection criteria. On the basis of the meta-analysis, the prevalence of deep venous thrombosis was 1.09% (95% confidence interval, 0.54% to 1.64%) and the prevalence of pulmonary embolism was 0.06% (95% confidence interval, 0.01% to 0.12%) following elective spine surgery. The use of pharmacologic prophylaxis significantly reduced the prevalence of deep venous thrombosis relative to either mechanical prophylaxis (p = 0.047) or no prophylaxis (p < 0.01). One fatal pulmonary embolism was reported. An epidural hematoma requiring surgical evacuation was reported in eight of 2071 patients receiving pharmacologic prophylaxis; three of these patients had a permanent neurologic deficit.
  
  
  CONCLUSIONS
  The risk of deep venous thrombosis and pulmonary embolism is relatively low following elective spine surgery, particularly for patients who receive pharmacologic prophylaxis. Unfortunately, pharmacologic prophylaxis exposes patients to a greater risk of epidural hematoma. More evidence is needed prior to establishing a protocol for prophylaxis against venous thromboembolic disease in patients undergoing elective spine surgery. Future prospective studies should seek to define the safety of various prophylactic modalities and to identify specific subpopulations of patients who are at greater risk for venous thromboembolism.
authors.affiliation: Department of Orthopedics and Rehabilitation, University of Wisconsin, Madison, WI 53792, USA.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Sansone
authors.forename: Alejandro Munoz
authors.initials: AM
authors.lastname: del Rio
authors.forename: Paul A
authors.initials: PA
authors.lastname: Anderson
mesh_terms: D015897:Comorbidity; D017558:Elective Surgical Procedures; D046748:Hematoma, Epidural, Spinal / Q000453:epidemiology; D006801:Humans; D016015:Logistic Models; D019637:Orthopedic Procedures; D015995:Prevalence; D011655:Pulmonary Embolism / Q000453:epidemiology* / Q000517:prevention & control; D012307:Risk Factors; D013122:Spinal Diseases / Q000601:surgery*; D013123:Spinal Fusion; D020246:Venous Thrombosis / Q000453:epidemiology* / Q000517:prevention & control