[Treatment persistence and adherence with botulinum toxin type A and anti-calcitonin gene-related peptide monoclonal antibodies in migraine. (A retrospective cohort study from a specialized headache center)].

OBJECTIVE

To compare the treatment persistence and adherence with botulinum toxin type A (Relatox; BTA) and monoclonal antibodies targeting calcitonin gene-related peptide (anti-CGRP mAb) among migraine patients in the real-world practice of a specialized headache center.

MATERIAL AND

METHODS

A single-center, retrospective cohort study was conducted using data from a specialized headache center over 12 months (from June 2025 to May 2026). The analytical cohort included 221 patients who received at least one injection of BTA or anti-CGRP mAb. Discontinuation of therapy was defined as a gap between doses of greater than 90 days for anti-CGRP mAb and greater than 180 days for BTA, in line with the efficacy assessment windows established by the International Headache Society. Treatment persistence was evaluated using the Kaplan-Meier method over a 12-month follow-up period following the initial injection, and adherence was assessed using the Proportion of Days Covered (PDC), with ≥80% considered high adherence. Both metrics were derived from documented dosing dates to ensure objectivity. Additionally, Cox proportional hazards regression was used to identify predictors.

RESULTS

The study cohort consisted of 183 females (82.8%) and 38 males (17.2%), with a mean age of 42.1±11.8 years. The median treatment persistence was 8.5 months [95% CI 6.1-11.4] for BTA compared to 3.9 months [95% CI 2.3-4.6] for anti-CGRP mAb; at 12 months, persistence rates were 35.0% and 11.5%, respectively (log-rank test p<0.001). At the first efficacy assessment window, 37.8% of patients receiving BTA (6 months) and 43.5% receiving anti-CGRP mAb (3 months) discontinued therapy. High adherence (PDC ≥80%) was found in 24.7% of patients treated with BTA and 10.7% of those treated with anti-CGRP mAb. Cox regression analysis revealed that the medication class was the sole independent predictor of persistence, with BTA reducing the risk of discontinuation by approximately 50% (HR 0.50; 95% CI 0.37-0.66; p<0.001).

CONCLUSION

In real-world clinical practice, treatment persistence and adherence for BTA are significantly superior to those observed for anti-CGRP mAb. Given that both endpoints are calculated from documented dosing dates, they are objective metrics. The primary reasons for the observed differences pertain to the dosing regimens (monthly for BTA versus quarterly for anti-CGRP mAb) and barriers to accessibility.