Rising to the challenge: an international Delphi consensus study on fetal and neonatal alloimmune thrombocytopenia.

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a condition in which a fetus is at risk for severe thrombocytopenia, possibly resulting in intracranial haemorrhage, due to maternal alloantibodies formed against human platelet antigens (HPAs). Currently, no FNAIT screening programme exists. Pregnancies at risk of FNAIT are identified in individuals who have previously given birth to a child with FNAIT. Management of the condition differs depending on the country. A panel of experts in obstetrics, neonatology, paediatrics, laboratory and transfusion medicine, haematology, health technology assessments, and population screening-related administration who are members of the FNAIT Modified Delphi Expert Group from Europe, the USA, Canada, and Australia, were invited to participate in this study. This Delphi study included three rounds of online questionnaires, which were formulated by professionals from the Dutch FNAIT centre of expertise in collaboration with co-authors, and one live meeting in Leiden, the Netherlands in April, 2023. Funding for the live meeting in Leiden was obtained from the Dutch Research Council. The final questionnaire had 35 statements on current management and a possible antenatal FNAIT screening programme. Answer options were: agree, disagree, neither agree or disagree, and not sufficient knowledge. Consensus threshold was set at 80%. After three rounds of questionnaires, consensus was reached on 25 (71%) of 35 statements. The experts agreed on the use of anti-HPA-1a antibody levels to identify high-risk FNAIT pregnancies, although a cutoff value was not defined. The panel achieved consensus on the design of a cost-effective screening programme based only on anti-HPA-1a antibody level measurement. International differences were observed in case of two aspects: addition of corticosteroids to intravenous immunoglobulins and delivery mode in FNAIT pregnancies. This Delphi study facilitated sharing of international knowledge, which enabled clarification of local policies related to perceived standards of care.