Costs and clinical outcomes of noninvasive fetal RhD typing for targeted prophylaxis

Abstract

Objective: To examine the cost and clinical outcomes of noninvasive RhD typing with cell-free fetal DNA to selectively deliver antenatal and postnatal prophylaxis with anti-D immune globulin for prevention of alloimmunization in RhD-negative women.

Methods: We developed a decision tree to compare the costs and clinical outcomes of three strategies in an RhD-negative nonalloimmunized population as follows: 1) routine antenatal anti-D immune globulin prophylaxis and postpartum prophylaxis guided by cord blood typing (the current approach in most of the United States); 2) noninvasive fetal RhD typing with prophylaxis guided by test results; and 3) no screening or prophylaxis. Costs were estimated for testing and treatment algorithms using hospital billing records and information from the manufacturer of the fetal RhD genotyping test. Probability estimates were derived from published literature. The decision tree and sensitivity analyses were constructed and performed with Microsoft Excel.

Results: We estimated the cost of the current approach to prevention of alloimmunization to be $351 per pregnancy, and we estimated the cost of noninvasive determination of fetal RhD status to be $682. Assuming essentially perfect test performance, threshold analysis found the cost must decrease to $119 to break even. The gap widened in favor of routine prophylaxis in most other circumstances (increased false-negative test rate and decreasing prevalence of RhD negativity).

Conclusion: Unless the cost of noninvasive fetal RhD typing is reduced substantially, routine antenatal anti-D immune globulin prophylaxis with postpartum prophylaxis guided by cord blood typing is less costly than noninvasive determination of fetal RhD status.