Anti-D choices remain limited

A recent paper published in Obstetrics and Gynecology (whose abstract is featured below) has analysed the cost effectiveness of noninvasive RhD typing with cell-free fetal DNA and concluded that this does not offer any significant cost benefit.

In other words, despite the recent development of testing in this area, women are not yet likely to be offered the option of finding out whether their baby is rhesus positive or rhesus negative before they need to decide whether or not they wish to have antenatal anti-D.

The latest paper, by Hawk et al (2013), is (at the time of posting) freely available online here and is not the first to analyse this area.  A paper published in BMC and based on research in Warwick by Szczepura et al (2011) reached similar conclusions, although an analysis of French data published earlier this year by Benachi et al (2013) also concluded that, while routine testing might not be cost effective, there may be other advantages.

This study demonstrates that fetal RhD genotyping early during pregnancy is not an effective cost-reduction strategy whether or not antenatal prophylaxis is given. The economic issues could, however, be overcome by the fact that there is a major clinical benefit to offering the test systematically to all RhD-negative pregnant women while avoiding unnecessary testing and immunoglobulin injections.  (Benachi et al 2013: 28)

All of these authors, however, acknowledge that such research has areas of weakness:

Our study has several weaknesses. We did not account for any of the adverse reactions associated with use of anti-D immune globulin. Not considering reactions such as pain, tenderness, erythema, swelling, and hypersensitivity might create bias in the analysis toward the routine prophylaxis strategy. We used a 37% cost-to-charge assumption, which is standard in South Carolina. Likewise, the costs of management of a sensitized pregnancy were based on our hospital charges at a state-funded public university hospital; different costs might be incurred elsewhere.  For the sake of analyses, we assumed an RhD-negative rate of 15%; therefore, rates of fetal RhD-positivity were applicable only to Caucasian-only unions. These percentages would be expected to differ based on the ethnicity of the population studied. We did not consider the percentage of either false-positive or inconclusive results in the noninvasive testing arm.  (Hawk et al 2013: 584).

Given the cultural location and focus of modern maternity services, it is perhaps inevitable that these papers have focused primarily on cost, taking the inevitable utilitarian approach:

The cost-savings associated with the 40% of patients who have RhD-negative fetuses cannot offset the majority who will incur the cost of both noninvasive testing and prophylaxis. (Hawk et al 2013: 584).

Sadly, as a consequence, and despite the fact that the ‘use of noninvasive testing would avoid 500,000 unnecessary administrations of anti-D immune globulin per 1 million pregnancies‘ (Hawk et al 2013: 582), this takes us no further towards increasing women’s choice.

 

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.

Hawk AF; Chang EY; Shields SM; et al, (2013).  Costs and Clinical Outcomes of Noninvasive Fetal RhD Typing for Targeted Prophylaxis. Obstetrics and Gynecology, September 2013, 122(3): 579-585. Online ahead of print.

 

References

Benachi A; Delahaye S; Leticee N; et al (2013). Impact of non-invasive fetal RhD genotyping on management costs of rhesus-D negative patients: results of a French pilot study. European Journal of Obstetrics and Gynecology and Reproductive Biology 162(1):28-32

Hawk AF; Chang EY; Shields SM; et al, (2013).  Costs and Clinical Outcomes of Noninvasive Fetal RhD Typing for Targeted Prophylaxis. Obstetrics and Gynecology, September 2013, 122(3): 579-585. Online ahead of print.

Szczepura A, Osipenko L and Freeman K (2011). A new fetal RHD genotyping test: Costs and benefits of mass testing to target antenatal anti-D prophylaxis in England and Wales. BMC Pregnancy and Childbirth. http://www.biomedcentral.com/content/pdf/1471-2393-11-5.pdf