The introduction of the CGRP monoclonal antibodies and their effect on the prescription patterns of chronic migraine preventive medications in a tertiary headache center: A retrospective, observational analysis

Objective: To determine the effect of the introduction of the calcitonin gene-related peptide monoclonal antibodies (CGRP mAbs) in 2018 on the prescribing of older medications for the prevention of chronic migraine.Background: Prior to 2018, the preventive treatment of migraine borrowed from medications intended to treat other illnesses with the last medication, onabotulinumtoxinA, receiving Food and Drug Administration (FDA) approval for the prevention of chronic migraine in 2010. The FDA approval of three CGRP mAbs in 2018 provided the ideal natural experiment to assess how the introduction of these medications, and a fourth in 2020, affected the generally stable migraine preventive medications market.Methods: We performed a retrospective cohort analysis using the aggregated de-identified data of 6595 patients. The percentage of patients with chronic migraine who had been prescribed one of ten most prescribed oral preventive medications or onabotulinumtoxinA, or any of the four CGRP mAbs, were calculated relative to the total number of patients with chronic migraine who received a prescription for any medication from our clinic during the pre-CGRP mAb years of 2015-2017 and post-approval years of 2019-2021.Results: We observed a statistically significant decrease in the prescription of the top 10 most prescribed medications after the introduction of the CGRP mAbs overall (1456/3144, 46.3%, to 1995/4629, 43.1%, p = 0.001), as well as with most individual medications, including large decreases in verapamil (230/3144, 7.3%, to 125/4629, 2.7%; p < 0.001), the tricyclic antidepressants (494/3144, 15.7%, to 532/4629, 11.5%; p < 0.001), topiramate (566/3144, 18.0%, to 653/4629, 14.1%; p < 0.001), and onabotulinumtoxinA (861/3144, 27.4%, to 1134/4629, 24.5%; p = 0.001).Conclusion: The introduction of the CGRP mAbs during 2018 resulted in a decrease in utilization of most oral medications and onabotulinumtoxinA for the prevention of migraine. Future work should continue to observe how the prescription patterns of these medications evolve with time.