Timing of plasma exchange for neuromyelitis optica spectrum disorders: A meta-analysis

Neuromyelitis optica spectrum disorders (NMOSDs) are autoimmune astrocytopathies with predominant involvement of the optic nerves and spinal cord. The current management is high-dose intravenous methylprednisolone, followed by apheresis therapy if it fails. We aimed to investigate plasma exchange (PE) benefits in corticosteroid-refractory NMOSDs.

From Embase, PubMed, Cochrane, Web of Science, and Clinical Trials, we identified PE-based studies published between Jan 2007 and Dec 2019. We pooled the information of these studies in a binomial meta-analysis. We investigated the factors affecting the efficacy of PE and its adverse events. The effectiveness of PE was assessed using the Expanded Disability Status Scale (EDSS). The timing of PE initiation was assessed using Spearman correlation analysis.

We included 561 records and identified 8 observational studies, including 228 NMOSD patients. The mean time to the initiation of PE was 11 days, and the average volume of each exchange was 1.5-2 L. PE treatment reduced the mean EDSS score by -1.04 (95% CI, -1.44 to -0.64). The initiation time of PE significantly affected the outcome (EDSS reduction) (P = 0.01; 95% CI, -1.30 to 0.28). In the ≤ 7-day and 8-23-day groups, the mean EDSS decreased by 0.64 (95% CI, -0.93 to -0.34) and 1.41 (95% CI, -1.79 to -1.02), respectively. In addition, PE showed the same efficacy for alleviating the symptoms of NMOSDs, regardless of the day between 8 to 23 days on which it was performed (P = 0.29). Thirty-five (20.8%) of the 168 patients had adverse events.

PE can ameliorate severe NMOSDs. PE effectiveness was associated with the duration between disease and the initiation of PE, and the optimal timing for PE initiation is 8 to 23 days after the onset of the disease.