What is the clinical evidence from this study?

Study design: Cohort. Population: Venous thromboembolism (n=492). Intervention: G20210A mutation in the prothrombin gene vs. Patients without the G20210A mutation. Primary outcome: Recurrent venous thromboembolism (RR 0.6, 95% CI 0.2-1.8, p=0.3).

January 1, 1999Thrombosis and Haemostasis134 citationsOpen Access

The Risk of Early Recurrent Venous Thromboembolism after Oral Anticoagulant Therapy in Patients with the G20210A Transition in the Prothrombin Gene

EMErich MinarVascular / Pulmonary Vascular MHMirko HirschlMusic and Arts University of the City of Vienna CBChristine BialonczykUniversity of Vienna

Key Result

The G20210A mutation in the prothrombin gene did not significantly increase the risk of early recurrent venous thromboembolism compared to non-carriers (RR 0.6, 95% CI 0.2-1.8).

Study Design

Type

Cohort (n=492)

Multicenter

Yes

Structured PICO

Does the G20210A transition in the prothrombin gene increase the risk of recurrent venous thromboembolism in patients with a history of VTE after discontinuation of oral anticoagulants?

Population

492 adult patients with a history of objectively documented venous thromboembolism, followed for a mean of 24 months after discontinuation of oral anticoagulants.

Exposure

Carrier of the G20210A transition in the prothrombin gene (n=42)

Comparator

Non-carriers of the G20210A mutation (n=450)

Outcome

Recurrent venous thromboembolismhard clinical

The G20210A mutation does not increase the risk of early recurrent venous thromboembolism, suggesting long-term secondary thromboprophylaxis is not justified for heterozygous carriers.

Main Result

Relative Risk: 0.6 (95% CI 0.2–1.8)

Absolute Event Rate: 8% vs 12.2%

p-value: p=0.3

Limitations

Some patients received secondary thromboprophylaxis for longer than 3-6 months, potentially attenuating differences between groups.
Mean observation time was only two years, limiting conclusions to early recurrence.
Small number of patients with the mutation limits the power of subgroup analyses.

Abstract

A G20210A transition in the prothrombin gene is a common risk factor of venous thrombosis. The risk of recurrent venous thromboembolism in carriers of the 20210A allele is unknown and guidelines for secondary thromboprophylaxis in these patients are not available. In a prospective multicenter trial, 492 patients with a history of objectively documented venous thromboembolism were followed for a mean observation time of 24+/-16 months after discontinuation of oral anticoagulants. Forty-two patients (8.5%) were carriers of the 20210A allele. Three of the 42 patients with the G20210A mutation (7%) and 54 of 450 patients without the mutation (12%) experienced recurrent venous thrombosis. At 24 months, the probability of recurrence was 8% (95% CI 0-16.7) in patients with the mutation and was 12.2% (95% CI 8.8-15.6) in patients without the mutation. In conclusion, the risk of early recurrent venous thromboembolism is not higher in patients with the G20210A mutation than in those without the mutation. Therefore, long-term secondary thromboprophylaxis with oral anticoagulants in heterozygous carriers of the 20210A allele is not justified.

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