Erenumab and Galcanezumab for Chronic Migraine Refractory to OnabotulinumtoxinA: A Real-World Comparative Study

BACKGROUND: Resistant chronic migraine remains a major therapeutic challenge, particularly in patients who continue to be symptomatic despite OnabotulinumtoxinA. Anti-calcitonin gene-related peptide (CGRP) monoclonal antibodies may provide effective preventive options, but comparative real-world data and quantification of acute medication reduction remain limited. OBJECTIVE: To compare the real-world effectiveness of erenumab versus galcanezumab in patients with chronic migraine refractory to OnabotulinumtoxinA and to evaluate changes in acute medication use. METHODS: We conducted a retrospective observational study of consecutive patients treated at a neurology outpatient clinic in Cantabria, Spain (ethics approval code 2022.204). Monthly migraine days (MMD) were recorded at baseline and during 3 follow-up visits. Acute medication use (monthly units of triptans and NSAIDs) was obtained from the electronic prescription dispensing system for the 6 months before and after treatment initiation. Changes in MMD were analyzed using a linear mixed-effects model. Acute medication changes were analyzed using a 2-way repeated-measures ANOVA (time pre/post × treatment group). RESULTS: = 0.344). CONCLUSION AND RELEVANCE: In patients with chronic migraine refractory to OnabotulinumtoxinA, erenumab and galcanezumab produced comparable and sustained reductions in migraine frequency, with high responder rates. Treatment was associated with reduced triptan use, supporting the clinical relevance of anti-CGRP monoclonal antibodies in this population.