Predictive Factors for Non-response to First Use of Polyvalent Intravenous Immunoglobulin in Generalised Myasthenia Gravis.

INTRODUCTION

Myasthenia gravis (MG) is an autoimmune neurological disorder affecting the neuromuscular junction. Rapid clinical deterioration during a myasthenic crisis (MC) or severe exacerbation may be life-threatening due to respiratory or bulbar involvement. Plasma exchange (PLEX) and intravenous immunoglobulin (IVIg) are two rescue therapies that show comparable efficacy in this setting. However, the characteristics of patients who respond poorly to IVIg remain insufficiently described. The aim of this study was to identify predictive factors of non-response to IVIg administered during a first MC or exacerbation.

METHODS

This was a single-centre retrospective cohort study carried out at a French referral centre for neuromuscular diseases between 2017 and 2023. Adult patients with generalised MG experiencing a first MC or exacerbation and treated for the first time with IVIg were included in the study. Data on clinical, laboratory, electrophysiological and therapeutic variables were collected. Treatment response was defined as the maximum gain in Garches clinical score following IVIg, adjusted for baseline score.

RESULTS

A total of 93 were included in the study. The median age of the cohort was 68 (interquartile range [IQR] 49-76) years, and the median delay from diagnosis was 0.7 years. The median baseline Garches score was 66/100 (IQR 55-75) points, which improved to 85/100 (IQR 75-94) points after treatment. Bulbar involvement was significantly associated with a greater response to IVIg.

CONCLUSIONS

In this large and heterogeneous cohort, IVIg demonstrated consistent efficacy without identification of significant predictors of non-response. These findings support IVIg as a reliable and evidence-based first-line therapy for patients with MG experiencing exacerbation or MC.