Use of Cluster Analysis to Validate IHS Diagnostic Criteria for Migraine and Tension-Type Headache


Address all correspondence to Dr. Stephen Bruehl, Room 904, Center for Pain Studies, Rehabilitation Institute of Chicago, 345 East Superior Street, Chicago, IL 60611.


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 clusters were consistent with IHS migraine and tension-type classifications, respectively. Replication using a non-hierarchical clustering technique, k-means cluster analysis, revealed a migrainelike patient cluster, reflecting more frequent pulsating, unilateral pain; more severe pain; and pain aggravated by activity; nausea, vomiting, photophobia, and phonophobia. A tensionlike patient cluster was also identified, reflecting more frequent pressing/tightening pain, mild to moderate pain, bilateral location, and absence of nausea/vomiting. These patient clusters were consistent across subsamples. International Headache Society diagnoses corresponded with classification based upon statistically derived clusters (P<.001). 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.