Cost-Effectiveness Of Thromboprophylaxis In Pregnant Women With Sickle Cell Disease
Authors: Rizvi Afshan H. , Smith Kenneth J. , Ragni Margaret V. 
Published: October 2019

Abstract

Background
Sickle cell disease (SCD) is the most common inherited blood disorder in the U.S., affecting 100,000 individuals, including 1 in 500 African Americans. Previous studies have shown that individuals with SCD have a higher rate of venous thromboembolism (VTE) than those without SCD. Women with SCD experience a higher rate of pregnancy-related complications, including a 2-fold higher VTE risk during pregnancy than unaffected women, and VTE is the major cause of maternal death in SCD. Further, among pregnant SCD patients with prior SCD complications, including pneumonia, vaso-occlusive disease, and/or acute chest syndrome, there is a 2-fold higher VTE risk (6%) than in those with SCD alone (3%). Yet, there are no guidelines on thromboprophylaxis in pregnant women with SCD; in fact, the American College of Chest Physicians guidelines do not address pregnant women with SCD. As VTE risk may be higher in pregnant women with SCD and the risk of bleeding is not known to be increased, we examined the cost-effectiveness of thromboprophylaxis to reduce pregnancy-associated VTE risk in women with SCD.

Methods
We constructed a Markov state-transition model using TreeAge Pro Suite 2013 comparing, in a hypothetical cohort of pregnant women with SCD and no previous VTE, prophylactic anticoagulation (AC) with enoxaparin, the anticoagulant of choice in pregnancy, to a strategy of no prophylactic AC. SCD pregnancies with previous pneumonia, vaso-occlusive disease, acute chest syndrome, and higher VTE risk were also assessed. The model was run over 15 months to account for acute VTE onset and treatment throughout pregnancy and postpartum. In the prophylactic AC strategy, pregnant women with SCD entered the model and prophylactic AC was continued throughout the pregnancy until 2 months postpartum. Transitions were simulated between several health states, including well, VTE, major bleeding, minor bleeding, and death. VTE risks and costs, major and minor bleeding rates, mortality rates, and quality of life utilities were obtained from the literature. The model analyzed antepartum and postpartum costs of prophylactic AC, as well as survival benefits. The outcomes included direct medical costs, effectiveness measured by VTE reduction, quality-adjusted life-years (QALY), and the incremental cost-effectiveness ratio (ICER). We also conducted a sensitivity analysis to assess the cost-effectiveness of varying baseline estimates within plausible ranges.

Results
Prophylactic AC in pregnant women with SCD cost less than $100,000/QALY gained when prophylactic AC cost less than $561 per month or when VTE risk exceeded 4.97%. For example, in women with SCD in whom the risk of VTE is ≥ 6.0%, i.e., those with prior SCD complications, prophylactic AC cost $76,811/QALY gained, well within the acceptable range. Results were much less sensitive to variation of other model parameters.

Discussion
For pregnant women with SCD, enoxaparin thromboprophylaxis is economically reasonable when the cost of enoxaparin is < $561 per month or the risk of VTE is > 5%, such as among pregnant women with SCD and prior pneumonia, vaso-occlusive disease, and/or acute chest syndrome. If high VTE rates are confirmed in prospective studies, enoxaparin thromboprophylaxis may be beneficial and economically reasonable in pregnant women with SCD.

Disclosures:
No relevant conflicts of interest to declare.