Seropositivity in Myasthenia Gravis as a Predictor of Response to Therapeutic Plasma Exchange

Abstract

Background: In spite of the increasing availability of immunomodulatory treatments for myasthenia gravis (MG), little is known about factors that predict response to the treatment. We aim to study if the presence of acetylcholine receptor (AChR) antibodies may be one of the predictors of the response to the therapeutic plasma exchange (TPE) in patients with MG. Methods: The study was carried out in 78 patients with moderate to severe MG. They were divided into two groups: TPE group (62 patients) that included the patients who received TPE, and control (non-TPE) group who did not receive TPE and was only on medical treatment (16 patients). Patients in TPE group, then, were subdivided into sero-positive and sero-negative subgroups according to the presence or absence of AChR antibodies respectively. Scoring by Quantitative Myasthenia Gravis Scale (QMGS) was done before and 1 month after the TPE. Results: After 1 month of treatment, the change in QMGS was significantly higher in the TPE group than in the Non-TPE one (t = -6.406) (P < 0.0001). In the sero-positive group, the score of QMGS ranged initially from 19 to 34 (mean 26.48 ± 3.75) and after 1 month from 11 to 30 (mean 18.00 ± 4.45) with the median change of -32. The QMGS change was significantly greater in the sero-positive group than in the sero-negative one (t = -3.516) (P < 0.0001). Conclusions: As regards to the presence of AChR antibodies in patients with MG, both sero-positive and sero-negative groups responded to TPE but the sero-positive group had a better response. J Neurol Res. 2019;9(1-2):8-13 doi: https://doi.org/10.14740/jnr510