Meta-regression
A meta-regression was conducted for placebo response, with the
percentage of patients with ≥2 treatment failures as a covariate for
both episodic and chronic migraine for SC trials. This step was intended
to assess whether the percentage of patients with ≥2 treatment failures
was significant and whether the coefficient estimate was similar between
two types of migraine across several SC trials. A similar assessment was
not feasible for IV trials, as there was only one trial for episodic
migraine and one trial for chronic migraine. Consequently, we conducted
a meta-regression including placebo data from all the anti-CGRP (SC and
IV) clinical trials identified in the systematic literature review to
understand the impact on placebo MMD response of the following
variables: type of migraine (episodic or chronic), percentage of
patients with ≥2 prior treatment failures in each trial, and the route
of administration for treatment (i.e., SC or IV). To assess whether the
route of administration impacted MMD reduction in the placebo arms
differently in episodic or chronic migraine, an interaction term between
the route of administration and type of migraine was introduced into the
meta-regression. Finally, we assessed whether the IV effect differed
between episodic and chronic migraine.