Cost comparison of intravenous immunoglobulin and subcutaneous efgartigimod in patients with chronic inflammatory demyelinating polyneuropathy

AIMS: To compare the total treatment costs and cost per responder of IVIG and a newer therapy for adults with chronic inflammatory demyelinating polyneuropathy from a U.S. payer perspective. METHODS: A cost per responder analysis compared Vyvgart hytrulo with Panzyga administered at standard (1 g/kg) and higher (2 g/kg) maintenance doses over 6- and 12-month time horizons. Efficacy, safety data, and responder definitions were sourced from the ADHERE trial for Vyvgart hytrulo, and the ProCID trial for Panzyga. Total treatment costs included drug acquisition, administration, and costs by responder status reported in 2026 USD. Twelve-month Panzyga response rates incorporated published evidence and clinical guideline assumptions for responders, non-responders, and those with inadequate initial response requiring dose escalation. Deterministic scenario analyses evaluated reduced Panzyga effectiveness and hypothetical Vyvgart Hytrulo average sales price (ASP) discounts. Threshold analyses identified the efficacy reduction and ASP discount required to change the model conclusions. Probabilistic sensitivity analysis evaluated parameter uncertainty in the clinical response estimates. RESULTS: At 6 months, total treatment costs for Panzyga 1 g/kg, Panzyga 2 g/kg, and Vyvgart hytrulo were $124,812, $217,366, and $464,681, respectively. At 12 months, costs were $190,026, $402,301, and $698,583, respectively. Six-month responder rates were 80%, 92%, and 53% for Panzyga 1 g/kg, Panzyga 2 g/kg, and Vyvgart hytrulo, respectively; corresponding 12-month rates were 74%, 85%, and 48%. Cost-per-responder was consistently lower for Panzyga versus Vyvgart hytrulo at both time horizons. At 12 months, cost per responder was $256,792 for Panzyga 1 g/kg, $473,295 for Panzyga 2 g/kg, and $1,455,382 for Vyvgart hytrulo. LIMITATIONS: While no head-to-head clinical trial data were available, differences in trial design and responder definitions between studies may affect comparability. CONCLUSIONS: Under the assumptions of this model, Panzyga-based treatment pathways were associated with lower modeled total treatment costs and lower estimated cost per responder than Vyvgart hytrulo at both 6 and 12 months.