Tracking Migraine Symptoms: A Longitudinal Comparison of Smartphone-Based Headache Diaries and Clinical Interviews

Background/Objectives: By leveraging the capabilities of a smartphone-based headache diary, the objective of this study was to determine the amount of agreement between migraine-associated symptomatology during headache events and the symptoms documented during clinician-led intake interviews. Methods: This was a 90-day longitudinal, smartphone-based headache calendar study for participants diagnosed with migraine. Registered headache events were labeled as "definite migraine", "probable migraine", and "not migraine" in accordance with the International Classification of Headache Disorders, Third Edition (ICHD-3) criteria. Symptoms' agreement with clinician-led intake interviews (agreement percentages and kappa coefficients), symptoms' similarity between headache events within users (percentage), and amount of newly registered ICHD-3 symptoms per participant were calculated. Results: Twenty-seven participants provided 505 headache events eligible for analysis. The median agreement between recorded headache event symptomatology and clinician-led intake interview phenotyping ranged between 40% (for events fulfilling "not migraine" criteria) and 55.5% ("definite migraine") (p < 0.001). Higher intraparticipant headache event pair similarity was observed for "definite migraine" pairs (p < 0.01), along with a decreasing trend in similarity as the attack-pair headache distance increases. Over half of the participants registered at least one new ICHD-3 symptom during the study. Conclusions: Electronic diary registrations show substantial longitudinal variability in intrapersonal headache symptomatology, with the similarity of headache events declining over time. The registration of a new ICHD-3 symptom was the rule rather than the exception.