IVIG and PLEX in the treatment of myasthenia gravis

Intravenous immunoglobulin (IVIG) and plasma exchange (PLEX) are used to treat myasthenia gravis (MG) but with little trial evidence. While a class I study provided evidence for the efficacy of IVIG treatment, the empirical support for PLEX has been less convincing until recently. In a randomized controlled single-masked study of 84 MG patients with moderate to severe disease, IVIG and PLEX had comparable efficacy as demonstrated by reduction in the Quantitative Myasthenia Gravis Score (QMGS) for disease severity, percentage of responders, persistence of treatment effect, and tolerability, which were similar in both treatment arms. The change in QMGS was accompanied by improved disease-specific quality of life. The only factor predicting response to treatment was baseline severity. FcR polymorphisms did not predict response to IVIG therapy, but an inhibitory polymorphism was associated with baseline disease severity. These studies support the choice of either IVIG or PLEX as comparable treatments in adult patients with moderate to severe MG.