title: Incidence of recurrent venous thromboembolism in relation to clinical and thrombophilic risk factors: prospective cohort study.
abstract: BACKGROUND
  Stratification for risk of recurrence after a first episode of venous thromboembolism (VTE) would affect the duration of anticoagulant therapy. We aimed to determine the incidence of recurrence of VTE in relation to clinical risk factors and standard laboratory testing for heritable thrombophilic defects.
  
  
  METHODS
  We established a database to prospectively follow-up a cohort of unselected patients who had had a first episode of objectively proven VTE. We excluded patients with malignant disease and antiphospholipid syndrome. All patients were offered testing for heritable thrombophilia.
  
  
  RESULTS
  At 2 years, the cumulative recurrence rate in 570 patients was 11%. Incidence was lowest after surgery-related VTE (0%) and highest after unprecipitated VTE (19.4%) (p<0.001). 85% of patients were tested for heritable thrombophilic defects. Recurrence rates were not related to presence or absence of laboratory evidence of heritable thrombophilia (hazard ratio 1.50 [95% CI 0.82-2.77]; p=0.187). In patients with a first event that was unprecipitated or was associated with a non-surgical trigger, recurrence rates did not differ in patients with or without thrombophilia (1.34 [0.73-2.46]; p=0.351).
  
  
  CONCLUSIONS
  In unselected patients who have had a first episode of VTE, testing for heritable thrombophilia does not allow prediction of recurrent VTE in the first 2 years after anticoagulant therapy is stopped. However, assessment of clinical risk factors associated with the first episode of VTE does predict risk of recurrence. Patients with postoperative VTE have a very low rate of recurrence.
authors.affiliation: Department of Haematology, Addenbrooke's NHS Trust, Cambridge, UK. tpb20@cam.ac.uk
authors.forename: Trevor
authors.initials: T
authors.lastname: Baglin
authors.forename: Roger
authors.initials: R
authors.lastname: Luddington
authors.forename: Karen
authors.initials: K
authors.lastname: Brown
authors.forename: Caroline
authors.initials: C
authors.lastname: Baglin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use; D020152:Antithrombin III Deficiency / Q000175:diagnosis / Q000453:epidemiology; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D020151:Protein C Deficiency / Q000175:diagnosis / Q000453:epidemiology; D018455:Protein S Deficiency / Q000175:diagnosis / Q000453:epidemiology; D012008:Recurrence; D012307:Risk Factors; D013923:Thromboembolism / Q000188:drug therapy / Q000453:epidemiology*; D019851:Thrombophilia / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics; D020246:Venous Thrombosis / Q000188:drug therapy / Q000453:epidemiology*
chemical_list: D000925:Anticoagulants