Purpose: Women with a history of prior venous thromboembolism have an increased risk for recurrence during pregnancy. Although thromboprophylaxis reduces this risk, recent evidence suggests that, in many cases, prophylaxis can be safely withheld because the estimated recurrence risk is very low. The balance of risks and benefits in women with different recurrence risks has not been examined.
Methods: We developed a Markov state transition decision analytic model to compare prophylactic low molecular weight heparin to expectant management for pregnant women with a single prior venous thromboembolism. A lifetime time horizon and societal perspective were assumed. Input data were obtained by literature review. Outcomes were expressed as U.S. dollars per quality-adjusted life-year (QALY).
Results: For "low-risk" women with a prior venous thromboembolism associated with a transient risk factor and no known thrombophilic condition (recurrence risk 0.5%), expectant management was both more effective and less costly than prophylaxis. For "high-risk" women with prior idiopathic venous thromboembolism or known thrombophilic condition (recurrence risk 5.9%), prophylaxis was associated with a reasonable cost-effectiveness ratio (USD 38,700 per QALY) given a risk of bleeding complications <1.0% (base case 0.5%).
Conclusion: For low-risk women with prior venous thromboembolism, expectant management during pregnancy leads to better outcomes than administration of prophylactic low molecular weight heparin. For high-risk women, antepartum thromboprophylaxis is a cost-effective use of resources.