Treatment Optimization with Add-On Kampo Therapy in Highly Refractory Migraine Patients with Inadequate Response or Re-Worsening During CGRP Monoclonal Antibody Therapy: A Real-World Treatment Episode Analysis

Background/Objectives: Although calcitonin gene-related peptide monoclonal antibodies (CGRP-mAbs) have improved migraine prevention, some patients continue to experience inadequate response or re-worsening during treatment. This study evaluated the effectiveness of add-on Kampo therapy in migraine patients receiving CGRP-mAb treatment. Methods: This retrospective observational study included 39 migraine patients who received add-on Kampo therapy during ongoing CGRP-mAb treatment, contributing 55 treatment episodes. The primary endpoint was the change in monthly headache days (MHD) from baseline to 1 month after Kampo initiation. Secondary outcomes included migraine frequency, headache-related disability, quality of life, acute medication use, and work productivity. A responder was defined as achieving a ≥30% reduction in MHD at 1 month. Results: The study population was highly refractory, with chronic migraine present in 79.5% of patients and medication-overuse headache in 56.4%. Among treatment episodes, 72.7% experienced re-worsening after an initial response to CGRP-mAb treatment. Median MHD was 14.0 days after CGRP-mAb treatment and subsequently increased to 16.0 days before Kampo initiation. After Kampo initiation, median MHD decreased to 10.0 days at 1 month. Significant improvements were also observed at 1 month in headache-related disability, quality of life, acute medication use, and presenteeism. The ≥30% and ≥50% responder rates at 1 month were 41.8% and 12.7%, respectively. Re-worsening after an initial CGRP-mAb response showed an exploratory association with treatment response in the Firth penalized logistic regression model. Conclusions: Add-on Kampo therapy was associated with improvements in headache burden, quality of life, acute medication use, and work productivity in patients with inadequate response or re-worsening during CGRP-mAb treatment. These hypothesis-generating findings suggest a potential role for add-on Kampo therapy as a treatment optimization strategy and warrant confirmation in prospective controlled studies.