Lymphoplasmapheresis versus plasma exchange in severe myasthenia gravis: a retrospective cohort study

Abstract

Background: Lymphoplasmapheresis (LPE) is a new therapy developed on the basis of traditional plasma exchange (PE) in combination with leukapheresis. Currently, it remains unclear whether PE and LPE show differences in efficacy for severe MG.

Methods: A retrospective analysis was conducted on 198 MG patients, 75 in the PE group and 123 in the LPE group, and the patients' Myasthenia Gravis Foundation of America (MGFA) Clinical Classification was Class IV. The treatment outcome was the change in Quantitative Myasthenia Gravis Score (QMGS) from baseline to the end of treatment. Propensity score matching (PSM) was applied for the balance of confounders between the two groups.

Results: In this study cohort, the safety profile of LPE and PE was good and no serious adverse events were observed. Based on PSM, 62 patients treated with LPE and 62 patients treated with PE were entered into a comparative efficacy analysis. In the PE group, patients underwent a total of 232 replacements, with a mean of 3.74. PE significantly improved the patients' QMGS performance, with the mean QMGS decreasing from 22.98 ± 4.03 points at baseline to 18.34 ± 5.03 points after treatment, a decrease of 4.68 ± 4.04 points (p < 0.001). A decrease of ≥3 points in QMGS was considered a significant improvement, with a treatment response rate of 67.7% in the PE group. In the LPE group, patients received a total of 117 replacements, with a mean of 1.89. The patients' mean QMGS was 23.19 ± 4.11 points at baseline and was 16.94 ± 5.78 points after treatment, a decrease of 6.26 ± 4.39 points (p < 0.001). The improvement in QMGS was more significant in patients treated with LPE compared to the PE group (p = 0.039). The treatment response rate in the LPE group was 79%, which was not significantly different compared to the PE group (p = 0.16). The LEP group had a shorter mean length of stay compared to the PE group (10.86 ± 3.96 vs. 12.14 ± 4.14 days), but the difference was not statistically significant (p = 0.13). During the 2-month follow-up period, LPE may be associated with better functional outcomes for patients, with lower QMG score and relapse rate. LPE and PE were both effective in reducing the levels of inflammatory cytokines (TNF-α, IL-1β, and IL-6) and AChR-Ab. Compared to PE, LPE was superior in the reduction of AChR-Ab titer.

Conclusion: In severe MG, LPE may be a more preferred treatment option than PE. It achieves treatment outcomes that are not inferior to or even better than PE with fewer replacements. This study provides further evidence to support the application of LPE as a new treatment option for MG.

Keywords: efficacy; lymphoplasmapheresis; myasthenia gravis; plasma exchange; therapy.

Figure 1

The flowchart designed for this study.

Figure 2

Comparison of the efficacy of LPE and PE. (A) Changes in QMGS before and after treatment in the PE group (n = 62). (B) Changes in QMGS before and after treatment in the LPE group (n = 62). (C) Comparison of QMGS improvement between the LPE and PE groups. (D) Comparison of effective rate between the LPE and PE groups. The bar represents the mean value; the error bar represents the standard deviation. ***p < 0.001; *p < 0.05; ns, no significance.

Figure 3

Comparison of LPE and PE in the follow-up period. (A) Comparison of hospital stay between the LPE group (n = 62) and PE group (n = 62). (B) Comparison of QMG scores between the LPE group (n = 49) and the PE group (n = 44) during follow-up. (C) Comparison of relapse rates between the LPE group and PE group. The bar represents the mean value; the error bar represents the standard deviation; ns, no significance.

Figure 4

Changes of immune indicators before and after LPE and PE treatment. (A) Changes of AChR-Ab titer before and after treatment; comparison of the change magnitude in AChR-Ab titer between the LPE and PE groups. (B) Changes of TNF-α level before and after treatment; comparison of the change magnitude in TNF-α between the LPE and PE groups. (C) Changes of IL-1β level before and after treatment; comparison of the change magnitude in IL-1β between the LPE and PE groups. (D) Changes of IL-6 level before and after treatment; comparison of the change magnitude in IL-6 between the LPE and PE groups. The bar represents the mean value; the error bar represents the standard deviation. ***p < 0.001, **p < 0.01; ns, no significance.