“…A summary of recent studies of children and adolescents that employed ICHD‐II criteria for headache is shown in Table . A total of 93,172 children were included in 21 studies in 13 countries (Brazil, China, Finland, Germany, India, Japan, Korea, Nigeria, Singapore, Sweden, Thailand, Turkey, US). Most of the studies administered questionnaires regarding ICHD‐II headache criteria to samples identified in schools.…”