Data sources
Data for this analysis were extracted from a systematic literature
review (see Figure 1 and Appendix S1 ). In brief,
electronic databases including Embase, MEDLINE, and the Cochrane Library
were searched for randomised, controlled trials of migraine-preventive
treatments from inception to June 2021. Additional grey literature
searching encompassed 2020–2021 headache/migraine congresses, the
ClinicalTrials.gov website, and several Health Technology Assessment
websites. Only clinical studies in humans, published in English
language, were selected. While the literature review was not fully
comprehensive, it was judged to be sufficiently complete for the
purposes of informing the current analysis. In addition, data on file
from the DELIVER trial (which was not yet published at the time of
conducting the analysis) was used to supplement the data identified by
the SLR.
<<<Note to Journal Editors: Place Fig. 1
here.>>>
We included data from published, placebo-controlled trials for
anti-CGRPs (18 articles detailing 14 studies) conducted in patients with
either episodic or chronic migraine . Where available, phase 3 or phase
4 randomised, controlled trials with a double-blind period of at least
12 weeks’ duration were identified. If such studies were unavailable for
any anti-CGRP, data from phase 2 randomised, controlled studies were
used instead. For this analysis, only data from the placebo arm of each
included trial were evaluated. For a few phase 3, anti-CGRP therapeutic
trials (ARISE, PROMISE-1, and PROMISE-2), the percentage of patients who
had failed ≥2 prior preventive migraine treatments could not be
identified in the literature; thus assumptions were made. The phase 3
ARISE study of erenumab 70 mg vs placebo in patients with episodic
migraine reported only the percentage of patients who had failed 1 or
more prior treatment (n=115/291, 39.5%) ; however, as this was
comparable with that reported in another phase 3 study of erenumab in
episodic migraine (STRIVE; n=127/391, 39.8%), it was assumed that the
percentage of patients who had failed ≥2 treatments in ARISE was the
same as the percentage in STRIVE. For the phase 3 studies of eptinezumab
(PROMISE-1 in episodic migraine ; PROMISE-2 in chronic migraine ), the
percentages of patients with ≥2 treatment failures were not captured in
the case report form; thus, it was assumed that there were no patients
with ≥2 treatment failures in either study. The potential implications
of this assumption are presented in the Discussion section. Informed
consent and Institutional Review Board approval were not applicable for
this publication.