title: Evaluation of recurrent venous thromboembolism in patients with Factor V Leiden mutation in heterozygous form.
abstract: BACKGROUND
  To evaluate the risk for recurrence after first venous thromboembolism (VTE) among patients with or without Factor V Leiden (FVL) mutation.
  
  
  METHODS
  A prospective population based study of 1465 consecutive unselected VTE patients was performed at Skåne University Hospital 1998-2008. The VTE was objectively verified and the patients answered questionnaire and left blood samples for evaluation.
  
  
  RESULTS
  Out of 1465 patients (721[49%] men and 744[51%] women) thrombophilia data were available for 1267, and FVL mutation was found in heterozygous form in 339 (27). The homozygous form and prothrombin mutation (PTM) were much less common. Patients were followed during 4.8 ± 2.3 years (total 6133 patient years) and recurrence after first VTE (evaluated in 1108 patients) occurred in 131 (12%, 95%CI 10-14%), where of 49(37%) had heterozygous FVL mutation and 57(44%) were without thrombophilia. The remaining 25(19%) patients had either PTM, FVL in homozygous form, compound PTM/FVL or unknown thrombophilia status. Having FVL mutation in heterozygous form significantly increased the risk for VTE recurrence (odds ratio 2.4 (95 %CI 1.6-3.6; p<0.01). In a Kaplan-Meier analysis the FVL group also differed significantly (p<0.01) from the other patients concerning time to recurrence (almost 25% vs. 10% after 8 years).
  
  
  CONCLUSIONS
  FVL mutation in heterozygous form is common among VTE patients and significantly increases the risk for VTE recurrence.
authors.affiliation: University of Lund, Skåne University Hospital, Malmö, Sweden. signy.sveinsdottir@med.lu.se
authors.forename: Signy V
authors.initials: SV
authors.lastname: Sveinsdottir
authors.forename: Ymir
authors.initials: Y
authors.lastname: Saemundsson
authors.forename: Nazim
authors.initials: N
authors.lastname: Isma
authors.forename: Anders
authors.initials: A
authors.lastname: Gottsäter
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Svensson
mesh_terms: D005165:Factor V / Q000235:genetics*; D005260:Female; D005819:Genetic Markers / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000453:epidemiology* / Q000235:genetics*; D006801:Humans; D015994:Incidence; D019656:Loss of Heterozygosity / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012008:Recurrence; D018570:Risk Assessment; D013548:Sweden; D054556:Venous Thromboembolism / Q000453:epidemiology* / Q000235:genetics*
chemical_list: D005819:Genetic Markers; C095381:factor V Leiden; D005165:Factor V