Barnett C, et al. - In this study, experts sought to examine responsiveness and meaningful change of the Myasthenia Gravis Impairment Index (MGII) and its relative efficiency compared to other measures. Among patients with myasthenia, the MGII showed responsiveness to prednisone, IV immunoglobulin (IVIg), and plasma exchange (PLEX). They found a differential response in ocular and generalized symptoms to the type of therapy. The MGII had higher relative efficiency than comparison measures and was viable for use in clinical trials.