Emicizumab for preventing intracranial hemorrhage in infants with severe hemophilia A: a cost-effectiveness analysis.

Intracranial hemorrhage (ICH) and resulting neurological disability are severe complications for a subset of infants with severe hemophilia A (HA). While prophylactic factor replacement reduces bleeding risk, it is typically delayed until after age 1 due to risks associated with central venous access placement. Emicizumab, a subcutaneous activated factor VIII (FVIII) mimetic, has demonstrated safety and efficacy in preventing ICH in infants under 12 months in the HAVEN 7 trial. Despite its high cost the cost-effectiveness of emicizumab prophylaxis initiated during the first year of life for infants with severe HA is not known. We developed a Markov cohort model to compare emicizumab prophylaxis to standard care (no prophylaxis) in infants aged 0-1 year with severe HA without FVIII inhibitors. The analysis was conducted from a US societal perspective over a lifetime time horizon across all accepted willingness-to-pay (WTP) thresholds. The primary outcome was the incremental cost-effectiveness ratio (ICER) in USD per quality-adjusted life-year (QALY). Emicizumab prophylaxis and standard care accrued 25.6 and 25.1 QALYs at costs of $13.12 and $13.07 million, respectively, resulting in an ICER of $99,900/QALY (95% credible interval 84,000-120,000). Scenario analysis examining prophylaxis with low-dose emicizumab resulted in an ICER of $19,600/QALY (95% CI 12,000-29,000). Probabilistic sensitivity analyses showed that standard-dose emicizumab is the cost-effective strategy in 100%, 66%, and 0% of 10,000 Monte Carlo iterations at WTP thresholds of $150,000, $104,000, and $50,000/QALY, respectively, and in 100% across all WTP thresholds for low-dose emicizumab.