IVIG Versus PLEX in the Treatment of Worsening Myasthenia Gravis: What is the Evidence? A Critically Appraised Topic

Background: Immune therapies such as intravenous immunoglobulin (IVIG) and plasma exchange (PLEX) are first line in the treatment of worsening myasthenia gravis. Although PLEX is favored in myasthenic crisis, IVIG is increasingly used in exacerbations due to cost and ease of administration. Objectives: To review and critically assess current evidence on the effects of IVIG and PLEX on functional outcomes in patients with worsening myasthenia gravis. Methods: A structured critical appraisal was conducted on the objective topic. This included a creation of a structured question based on a clinical scenario, comprehensive literature search, selection of evidence for review, and critical appraisal of selected evidence. Evidence was summarized and commentary provided. Participants included consultant and resident neurologists, a medical librarian, clinical epidemiologists, and content experts in the field of neuromuscular neurology. Results: A single-blinded, randomized-controlled trial that compared IVIG and PLEX in 84 patients with worsening myasthenia gravis was selected for review. Primary outcome measure was functional status at 14 days after treatment, as assessed by the Quantitative Myasthenia Gravis Score. Change in Quantitative Myasthenia Gravis Score at day 14 for all subjects was 4.0, without statistically significant differences between IVIG and PLEX groups. Conclusions: IVIG and PLEX are equally effective in worsening myasthenia gravis. Treatment decisions may depend on several variables, including presence of respiratory distress, medical comorbidities, access to medication, and cost. PLEX will likely remain the treatment of choice in true myasthenic crisis.