A RISK-BENEFIT ANALYSIS OF FACTOR V LEIDEN TESTING TO IMPROVE PREGNANCY OUTCOMES AMONG HIGH-RISK WOMEN

Purpose: Women who are carriers of the Factor V Leiden mutation are believed to be at greater risk of venous thromboembolism and adverse pregnancy outcomes than non-carriers; however, the potential utility of a genetic test for Factor V Leiden in this setting has not formally been assessed.  

Method: We used decision analytic methods to model the potential risks and benefits of testing in a hypothetical cohort of 10,000 pregnant women with a history of recurrent pregnancy loss.  In the intervention arm, all women were tested, and we assumed that women testing positive for the Factor V Leiden mutation would be treated with low molecular weight heparin; those testing negative were assumed to remain untreated.  In the comparator arm, none of the women were tested nor did they receive treatment.  Outcomes of interest included venous thromboembolism, major bleed due to treatment with low molecular weight heparin, pregnancy loss, and maternal mortality.  Outcomes were assessed for the duration of pregnancy and six weeks post-partum, and impacts of mortality were captured over a lifetime.  Disutilities were applied for each outcome of interest to inform the change in lifetime QALYs.  Data sources included English language literature obtained through PubMed.  Scenario and sensitivity analyses were conducted to test robustness of findings with respect to key parameters and assess various clinical scenarios.

Result: The use of Factor V Leiden testing to guide use of low molecular weight heparin resulted in a reduction of 10 venous thromboembolic events and 367 pregnancy losses, and an increase of 24 major bleeding events per 10,000 women tested.  On a per-patient tested basis, testing resulted in 0.002 QALYs gained over the one-year timeframe, and 0.0609 QALYs gained in the lifetime analysis.  

Conclusion: These findings suggest use of the Factor V Leiden test in this population may offer important tradeoffs between clinical and personal utility.  Further analysis is required to more thoroughly account for the impacts of pregnancy loss on the woman and fetus and to assess the impact on other pregnancy-related outcomes.