Headache
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Cluster analysis was used to validate headache diagnostic criteria of the International Headache Society (IHS). Structured diagnostic interviews were conducted on 443 headache sufferers from a community sample, which was randomly split to allow replication. Hierarchical cluster analysis of symptoms in both subsamples revealed two distinct (P<.001) clusters: (1) unilateral pulsating pain, pain aggravated by activity, and photophobia and phonophobia, and (2) bilateral pressing/tightening pain, mild to moderate intensity, and absence of nausea/vomiting. ⋯ These results indicate that headache symptoms cluster empirically in a manner consistent with IHS criteria for migraine and tension-type headaches. Criterion overlap problems regarding pain intensity and duration were identified. Overall, these data support migraine and tension-type headache as distinct entities, and provide support for the IHS diagnostic criteria with minor modifications.