BACKGROUND: Calcitonin gene-related peptide monoclonal antibodies (CGRP mAbs) are effective migraine-specific preventive therapies; however, access remains limited in many low- and middle-income countries (LMICs). In such settings, oral migraine preventive medications (OMPMs) continue to serve as the foundation of preventive care. The association between baseline preventive regimens and real-world escalation to CGRP mAbs has not been well characterized. METHODS: We conducted a single-center retrospective cohort study of adults with migraine attending a university-based headache clinic in Thailand between January 2021 and December 2023. Participants with at least one baseline OMPM, no prior CGRP mAb exposure, and at least 6 months of follow-up were included. Multivariable Cox proportional hazards models, adjusted for age, sex, and migraine subtype, were used to examine associations between baseline OMPM classes and CGRP mAb initiation. A secondary analysis evaluated factors associated with discontinuation of baseline OMPMs. RESULTS: Among 80 participants, 16 (20.0%) initiated CGRP mAbs over 11,554 person-days of follow-up, with a median time to initiation of 44.5 days. Baseline use of beta-blockers (BBs) or tricyclic antidepressants (TCAs) was independently associated with a lower likelihood of CGRP mAb initiation (BB: adjusted hazard ratio aHR 0.17, 95% CI 0.04-0.66; TCA: aHR 0.12, 95% CI 0.02-0.57). In secondary analyses, baseline BB use was also associated with greater persistence with preventive therapy (aHR for discontinuation 0.24, 95% CI 0.09-0.64). CONCLUSIONS: Baseline oral preventive regimens were associated with differing likelihoods of switching to CGRP mAbs in this LMIC setting. Optimizing oral preventive treatment strategies remains essential in settings where access to CGRP-targeted therapies is limited, either due to unavailability or lack of reimbursement.
Thanprasertsuk et al. (2026) studied this question.