Cost-Effectiveness Analysis of Efgartigimod vs Chronic Immunoglobulin for the Treatment of Myasthenia Gravis in Canada.

INTRODUCTION

Generalized myasthenia gravis (gMG) is a chronic neuromuscular disease that causes muscle weakness and fatigue, severely impairing quality of life. Efgartigimod is a novel drug that is recently approved for treatment of acetylcholine receptor antibody-positive (AChR-Ab+) gMG patients in Canada. In clinical practice, it is expected to be used in AChR-Ab+ gMG patients who continue to experience symptoms despite conventional therapy and primarily replace chronic immunoglobulins.

METHODS

A Markov model was developed to estimate costs and benefits (measured as quality-adjusted life years [QALYs]) of efgartigimod and chronic immunoglobulins for AChR-Ab+ gMG patients. The analysis was conducted from the perspective of the Canadian publicly funded healthcare system over a lifetime horizon. The model comprised six health states based on Myasthenia Gravis Activities of Daily Living (MG-ADL) scores: MG-ADL < 5, MG-ADL 5-7, MG-ADL 8-9, MG-ADL ≥ 10, myasthenic crisis or death. Health state transition probabilities were estimated from the ADAPT and ADAPT+ studies, plus a network meta-analysis that compared efgartigimod against chronic immunoglobulins. The MyRealWorld MG study informed utility values. Modeled costs included treatment and administration, disease monitoring, complications from chronic corticosteroid use, exacerbation/crisis management, adverse events and end-of-life care.

RESULTS

Over a lifetime horizon, efgartigimod and chronic immunoglobulins 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 immunoglobulins with incremental QALYs of 3.45 and cost savings of $257,020.

CONCLUSIONS

Efgartigimod provides greater benefit in terms of lower costs than chronic immunoglobulins for AChR-Ab+ gMG patients in Canada.