Relevance and costs of RHD genotyping in women with a weak D phenotype

• Published in: Transfusion clinique et biologique : journal de la Société française de transfusion sanguine 2019-02, Vol.26 (1), p.27-31
• Main Authors: Laget, L., Izard, C., Durieux-Roussel, E., Gouvitsos, J., Dettori, I., Chiaroni, J., Ferrera-Tourenc, V.
• Format: Article
• Language: English
• Subjects: D faible; D partiel; Génotypage du gène RHD; Life Sciences; Partial D; Phénotype D affaibli; Prophylaxie anti-D; RHD genotyping; RhIG prophylaxis; Weak D; Weak D phenotype
• ISSN: 1246-7820; 1953-8022
• DOI: 10.1016/j.tracli.2018.05.001

For pregnant women, the serologic test results of D antigen will determine the frequency of RBC antibody detection as well as the indication for RhIG prophylaxis. RHD genotyping is the only method that may provide clear guidance on prophylaxis for women with a weak D phenotype. This analysis evaluated the economical implications of using RHD genotyping to guide RhIG prophylaxis among pregnant women with a serological weak D phenotype. We compared the costs of 2 strategies in a cohort of 273 women with weak D phenotype. In the first strategy, we did not perform genotyping and all women with weak D phenotypes were treated as if they were D−, thus considered to be a risk of RhD alloimmunization. These women all received the prophylactic follow up. In the second strategy, RHD genotyping was performed on all women with a serologic weak D phenotype. Then, the follow-up will be determined by phenotype deduced from genotype. On the studied cohort, the additional expense occurred by genotyping is 26,536 €. RHD Genotyping has highlighted 162 weak D Type 1, 2 3, that could safely be managed as D+ and 111 partial D to consider as D−. By comparing the 2 strategies, the savings generated by genotyping the patients of our cohort are € 12,046 for the follow up of one pregnancy. Knowing that in France, a woman has on average 2 pregnancies and that the genotyping is carried out only once, the savings generated for the following pregnancies would be € 38,581. Performing RHD genotyping for pregnant women with a weak D phenotype enables to clearly identify weak D type 1, 2 or 3 from the other variants at risk of alloimmunization. This analysis generates savings in terms of follow-up schedule of pregnant women and RhIG prophylaxis. It also allows saving of D− products for patient with a weak D type 1, 2 or 3 in case of a transfusion need. Chez la femme enceinte, le statut RH : 1 ou RH : −1 détermine le calendrier de suivi immuno-hématologique ainsi que l’indication d’une prophylaxie anti-D. Seul le génotypage permet de déterminer ce statut en cas d’affaiblissement antigénique RH1. L’objectif de notre travail est d’évaluer l’intérêt et l’impact financier du génotypage RHD des patientes présentant un antigène RH1 affaibli dans le cadre du suivi immuno-hématologique obstétrical. Nous avons comparé les coûts de 2 stratégies sur une cohorte de 273 patientes. Dans la première stratégie sans génotypage RHD : toutes les patientes avec affaiblissement RH1 en sérologie sont considérées c