Overview of Immunotherapy Administration for Miller Fisher Syndrome in Japan: A Nationwide Retrospective Cohort Study

Miller Fisher syndrome (MFS) is typically associated with a benign course and spontaneous recovery. However, immunotherapies such as intravenous immunoglobulin (IVIG) and plasma exchange (PE) are often administered for this condition because of the potential for clinical deterioration. We aimed to evaluate the real-world use of immunotherapies in MFS management using a nationwide Japanese database.

We conducted a retrospective cohort study between April 2014 and March 2020 using the Japanese Diagnosis Procedure Combination database. Patient demographics and treatment modalities were described. Outcomes included length of hospital stay, in-hospital mortality, hospitalization cost, and activities of daily living defined by the Barthel index score.

We identified 1,595 patients with MFS. Of these, 999 (62.6%) received immunotherapy (including IVIG for 908 [56.9%] patients, intravenous methylprednisolone for 219 [13.7%] patients, and PE for 18 [1.8%] patients). In patients with and without immunotherapy, the median length of hospital stay was 18 and 12 days, in-hospital mortality was 0.7% and 0.2%, median total hospitalization costs were ¥1,660,200 and ¥549,375, and the proportions of Barthel index score of 95-100 at discharge were 75.3% and 75.2%, respectively.

Our findings highlight the widespread use of immunotherapies for MFS in Japan despite its generally favorable natural course.