Double Filtration Plasmapheresis Shows Superior Short-Term Efficacy to Intravenous Methylprednisolone in Acute Autoimmune Encephalitis: A Prospective Observational Study

BACKGROUND: Autoimmune encephalitis (AE) is a severe neurological disorder, but limited evidence comparing the efficacy of double filtration plasmapheresis (DFPP) and intravenous methylprednisolone (IVMP) as first-line treatments in the acute phase. This study aimed to evaluate the clinical outcomes of DFPP versus IVMP in antibody-positive patients with AE. METHODS: A prospective observational cohort study was conducted at Renji Hospital from July 2018 to May 2024. Thirty-eight patients with antibody-confirmed AE in the acute phase who received either DFPP (n=22) or IVMP (n=16) as first-line therapy were included. The primary outcome was improvement in the Modified Rankin Scale (mRS), and the secondary outcome was improvement in the Clinical Assessment Scale for Autoimmune Encephalitis (CASE). Adverse events were recorded for safety assessment. Univariate and multivariate logistic regression analyses were performed. RESULTS: The DFPP group demonstrated significantly higher rates of functional improvement, with 68.2% (15/22) achieving mRS reduction compared to 31.3% (5/16) in the IVMP group (p=0.047). Similarly, symptomatic improvement (CASE score reduction) was observed in 72.7% (17/22) of DFPP patients versus 43.8% (7/16) with IVMP (p=0.099). Multivariate analysis identified DFPP as the sole independent predictor of better outcomes (OR: 5.234, 95% CI: 1.179-23.235, p=0.030). Adverse events were limited to the DFPP group (3/22), including manageable deep venous thrombosis and hepatic impairment. CONCLUSION: DFPP demonstrated superior short-term efficacy compared to IVMP in improving functional and symptomatic outcomes in acute-phase AE, suggesting its potential as a preferred first-line therapy. Further large-scale randomized trials are warranted to validate these findings.