To assess the cost-effectiveness of efgartigimod versus chronic intravenous immunoglobulin (IVIg) for adults with acetylcholine receptor antibody positive (AChR-Ab+) generalized myasthenia gravis (gMG).

Efgartigimod is a first-in-class human IgG1 antibody Fc fragment recently approved by Health Canada in 2023 for AChR-Ab+ gMG. Efgartigimod is expected to use among AChR-Ab+ MG patients whose symptom persists despite treatment of CT and primarily displace chronic IVIg in clinical practice.

A Markov model was developed to estimate costs and benefits (measured as quality-adjusted-life-years [QALYs]) of efgartigimod and chronic IVIg for AChR-Ab+ gMG patients in Canada. The analysis was conducted from the Canadian publicly funded healthcare system perspective over a lifetime horizon. The model comprised six health states: MG-ADL <5, MG-ADL 5–7, MG-ADL 8–9, MG-ADL ≥10, myasthenic crisis, or death. Health state transition probabilities were estimated using data from the ADAPT and ADAPT+ studies, plus a network meta-analysis that compared efgartigimod against chronic IVIg. Utility values were obtained from the MyRealWorld MG study. Modeled costs included treatment and administration, disease monitoring, complications from chronic use of corticosteroids, exacerbation and crisis management, adverse event, and end-of-life care. Patients receiving efgartigimod or chronic IVIg with MG-ADL ≥5 and did not die/discontinue were assumed to receive the treatment every 4 weeks or every 3 weeks over the lifetime horizon.

Over a lifetime horizon, efgartigimod and chronic IVIg were predicted to have total discounted QALYs of 16.80 and 13.35, and total discounted costs of $1,913,294 and $2,170,315, respectively. Efgartigimod dominated chronic IVIg with incremental QALYs of 3.45 and cost savings of $257,020.

Efgartigimod provides greater benefit at lower costs than chronic IVIg for AChR-Ab+ gMG patients whose symptoms persists despite treatment with CT in Canada. Limitations include model assumptions on treatment utilization and limited public evidence on chronic IVIg efficacy.