Short delay to initiate plasma exchange or immunoadsorption as synergistic therapies for patients in the acute phase of anti-NMDAR encephalitis

Background: Combined first-line therapies have been frequently adopted for patients with anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis. Plasma exchange (PE) or immunoadsorption (IA) was used as an add-on option following initial immunotherapies, including high-dose steroids and intravenous immunoglobulin (IVIG). However, whether a shorter delay of PE or IA can improve the early recovery prognosis of patients with anti-NMDAR encephalitis remains largely unknown. Objective: To compare short-term clinical improvement between patients with early and late initiation of PE or IA in anti-NMDAR encephalitis. Design: A retrospective study was conducted for patients admitted with anti-NMDAR encephalitis between January 2015 and December 2023 ( n = 29), including 21 patients who received PE or IA as synergistic therapies. Methods: The clinical prognosis was compared between the early PE/IA group and the late PE/IA group in the research. Primary outcome included changes in the Clinical Assessment Scale for Autoimmune Encephalitis (∆CASE) at 90 and 120 days after encephalitis onset. Secondary outcomes included changes in the modified Rankin scale (∆mRS) after 90 and 120 days from encephalitis onset, and the length of intensive care unit (ICU) stay for patients with severe anti-NMDAR encephalitis. Results: The ∆CASE scores after 90 and 120 days from encephalitis onset revealed a significant difference between patients with early and late initiation of PE or IA ( p ⩽ 0.05). A significant difference in the ∆mRS was also found between patients with early and late initiation of PE or IA in severe encephalitis ( p ⩽ 0.05). No significant difference was found in the length of ICU admission ( p = 0.101). Conclusion: Our findings emphasize the importance of considering PE or IA as early as feasible for patients with anti-NMDAR encephalitis, even when steroids and IVIG are in use.