title: The occurrence of venous thromboembolism in cancer patients following major surgery.
abstract: BACKGROUND
  Venous thromboembolism (VTE), encompassing deep vein thrombosis (DVT) and pulmonary embolism (PE), is common in cancer patients and surgery is an important risk factor.
  
  
  OBJECTIVE
  To describe the occurrence of VTE in cancer patients following major surgery and to determine the risk of VTE recurrence.
  
  
  METHODS
  Using the administrative health claims (RAMQ) and hospital discharge (MED-ECHO) databases of the province of Québec, Canada, we constructed a cohort of all individuals with incident VTE between January 1, 1994 and December 31, 2004 diagnosed with cancer and who had major surgery in the 91days prior to the VTE. The timing of VTE after surgery was determined. Recurrent VTE was defined as re-hospitalization with a principal discharge diagnosis of VTE.
  
  
  RESULTS
  Our cohort consisted of 2706 cancer patients with VTE following major surgery. The mean age was 65.9years (Standard Deviation 12.6) and 54% were female. The median duration of surgical hospitalization was 18days (range 1-735days). The median time to VTE following surgery was 15days (range 1-659days), and 34% of VTE events were diagnosed after hospital discharge. The 1-year cumulative rate of recurrence was 6.7% (95% CI 5.7, 7.9) and the 5-year cumulative rate was 12.6% (95% CI 10.7, 14.7). Increasing comorbidity (adjusted hazard ratio (HR) 2.49, 95% CI 1.58-3.95) and VTE diagnosed after hospital discharge (adjusted HR 1.48, 95% CI 1.09-2.01) were associated with recurrence.
  
  
  CONCLUSIONS
  A significant proportion of VTE episodes among surgical patients with cancer are diagnosed after discharge from hospital. This suggests that surgical patients with cancer are at risk for VTE beyond the immediate postoperative period.
authors.affiliation: Department of Medicine, Jewish General Hospital, McGill University, Montréal, QC, Canada.
authors.forename: Thierry H
authors.initials: TH
authors.lastname: Toledano
authors.forename: Dimple
authors.initials: D
authors.lastname: Kondal
authors.forename: Susan R
authors.initials: SR
authors.lastname: Kahn
authors.forename: Vicky
authors.initials: V
authors.lastname: Tagalakis
mesh_terms: D000328:Adult; D000368:Aged; D016009:Chi-Square Distribution; D015897:Comorbidity; D005260:Female; D006801:Humans; D015994:Incidence; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009369:Neoplasms / Q000453:epidemiology / Q000601:surgery*; D010351:Patient Discharge; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology*; D016016:Proportional Hazards Models; D011655:Pulmonary Embolism / Q000175:diagnosis / Q000453:epidemiology; D011792:Quebec / Q000453:epidemiology; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D054556:Venous Thromboembolism / Q000175:diagnosis / Q000453:epidemiology*; D020246:Venous Thrombosis / Q000175:diagnosis / Q000453:epidemiology