Risk for subsequent venous thromboembolic complications in carriers of theprothrombin or the factor V gene mutation with a first episode of deep-vein thrombosis

Carriers of a mutation in the prothrombin (clotting factor II) or factor V gene have a 2- to 4-fold greater risk for venous thromboembolism than subje cts without the mutations. Whether both mutations also predispose to recurr ent venous thromboembolism is unclear. Outpatients who had a first episode of proven symptomatic deep-vein thrombosis and a long-term follow-up were s tudied. The outcome measure was the cumulative incidence of confirmed venou s thromboembolic complications. Two hundred fifty-one patients were enrolle d in the study, Mean duration of follow-up was 8.3 years. The prothrombin g ene mutation was demonstrated in 27 patients (prevalence, 10.8%; 95% CI, 6. 9 to 14.6), and the factor V gene mutation was demonstrated in 41 patients (prevalence, 16.3%; 95% CI, 11.8 to 20.9). The cumulative incidence of veno us thromboembolic complications after 10 years was 61.3% (95% CI, 35.7 to 8 7.9), and the hazard ratio was 2.4 (95% CI, 1.3 to 4.7; P = .004) in patien ts with the prothrombin gene mutation); the cumulative incidence of venous thromboembolic complications after 10 years was 55.2% (95% CI, 36.4 to 74.0 ), and the hazard ratio was 2.4 (95% CI, 1.4 to 4.1; P = .001) in patients with the factor V gene mutation. In comparison, the cumulative incidence of venous thromboembolic complications after 10 years was 23.1% (95% CI, 16.2 to 30.1) in patients without the mutations, Prothrombin and factor V gene mutations occur frequently in patients with venous thrombosis and are assoc iated with an increased risk for recurrent venous thromboembolic complicati ons. (C) 2000 by The American Society of Hematology.