Plasma exchange for acute optic neuritis in neuromyelitis optica or neuromyelitis optica spectrum disorder: a systematic review

OBJECTIVES: To appraise whether plasma exchange (PLEX) effectively improves visual function for acute optic neuritis (ON) in neuromyelitis optica (NMO) or neuromyelitis optica spectrum disorder (NMOSD). METHODS AND ANALYSIS: We searched Medline, Embase, Cochrane Library, ProQuest Central, and Web of Science to identify relevant articles published between 2006 and 2020. Eligible studies were in English and evaluated visual outcomes for people with acute ON in NMO or NMOSD treated with PLEX. They also had adequate pre- and posttreatment data. Excluded were studies with 1 or 2 case reports, or incomplete data. RESULTS: Twelve studies were qualitatively synthesized (1 RCT; 1 controlled NRSI; 10 observational studies). Five before-and-after observational studies were used for quantitative synthesis. The PLEX in the 5 studies (3 to 7 cycles over 2 to 3 weeks) was performed as second-line or adjunctive therapy for acute ON in NMO/NMOSD. The qualitative synthesis revealed that visual-acuity recovery occurred between one day and 6 months after the first PLEX cycle completion. Thirty-two of 48 participants in the 5 quantitative-synthesis studies received PLEX. Relative to pre-PLEX values, visual-acuity improvements were nonsignificant at these post-PLEX time points: 1 day (SMD 0.611; 95% CI −0.620 to 1.842); 2 weeks (SMD 0.0214; 95% CI −1.250 to 1.293); 3 months (SMD 1.014; 95% CI −0.954 to 2.982); and 6 months (SMD 0.450; 95% CI −2.643 to 3.543). CONCLUSIONS: There were inadequate data to determine whether PLEX effectively treats acute ON in NMO/NMOSD.