Impact of preventive pill-based treatment on migraine days: A secondary outcome study of the Childhood and Adolescent Migraine Prevention (CHAMP) trial and a comparison of self-report to nosology-derived assessments.

Regardless of treatment, CHAMP trial completers showed clinically important reductions in self-reported migraine days over the course of the trial (about 3.8 days less). The strong association between self-reported and "nosology-derived" migraine days suggests youth with migraine can recognize a day with migraine and reliably report their headache features and symptoms. Greater rigor and transparency in the calculation and reporting of migraine days in trials is needed.