Background: Migraine trial guidelines recommend prospective collection of headache features but there is no strong consensus on the definition of “migraine-day”. Such variations impact interpretation of one of the most common primary endpoints within migraine trials. In this study, we determined agreement between self-reported migraine and migraine according to diagnostic guidelines for children and adolescents who completed a headache diary.

Methods: This is a secondary analysis of text message-based headache diary data collected from participants in 2 larger projects for 4 or 12 weeks (depending on treatment). Participants completed a detailed headache assessment on 20% of self-reported headache-days from which we determined whether a headache-day met criteria for migraine or probable migraine, based on International Classification of Headache Disorders (ICHD). We calculated positive and negative predictive values (PPV; NPV) and Cohen’s Kappa (Kappa), comparing self-reported and ICHD-defined migraine.

Results: Of the 116 children and adolescents enrolled, 100 completed ≥1 detailed assessments during follow-up (419 entries). We found poor agreement between self-reported and ICHD-defined migraine, with a Kappa of 0.39 and PPV of 0.51, and NPV of 0.88. Allowing for ICHD-defined probable migraine increased PPV (0.51 [95% CI: 0.40-0.61] vs. 0.88 [0.81-0.94]) but Kappa did not change significantly (0.39 [0.28-0.50] vs. 0.32 [0.19-0.45]).

Conclusion: We found low agreement between self-reported and ICHD-defined migraine, even after including ICHD-defined probable migraine. This suggests that both measures are qualitatively different and may represent different aspects of migraine as a disease. Future studies would benefit from greater methodological transparency to avoid readers conflating both measures.