The psychometric properties of an e-headache diary in migraine

Objective To evaluate the psychometric characteristics of a previously validated electronic headache diary with automated algorithm for the purpose of identifying migraine days. Methods The psychometric properties of 13 variables in this e-diary were analyzed using item response theory (IRT) in migraine patients from the Leiden Headache Center. The included items were headache presence, duration, unilaterality, severity, pulsating, aggravation by physical activity, visual aura, aura duration, nausea, vomiting, photophobia or phonophobia and triptan usage. The added value to the end-diagnosis of an already validated migraine day of the individual items was assessed. A generalized partial credit model was used to evaluate the items. A discriminative value α ≥ 1.70 indicated an excellent discrimination. Results In total 1418 migraine patients were analyzed with a mean age of 43 years, 89% were women and 38% reported aura symptomatology. All items demonstrated excellent discriminative value [α: 1.82–54.1], except for aura duration [α:0.86], which was moderate. Cronbach's alpha was 0.91. The answers options of headache duration, photophobia, phonophobia, nausea and vomiting did not reach the probability threshold of 0.5. Conclusions The items in this e-headache diary demonstrated good overall psychometric performance, although certain items, particularly aura-related and multi-categorical items, may benefit from category merging or further refinement.