Interobserver reliability of diagnostic criteria for cervicogenic headache.

To assess the interobserver reliability in distinguishing cervicogenic headache (CEH) from migraine without aura and tension-type headache we conducted a study keeping as closely as possible to daily clinical practice. In contrast to other reliability studies, which use data from clinical patient records or semi-structured interviews recorded on videotape ('in vitro' design), we examined 'live' patients ('in vivo' design). Twenty-four headache patients participated in our 'in vivo' design experiment. During a session, each physician performed a physical examination and queried six patients in succession using a semi-structured interview. Diagnosis was carried out in accordance with the International Headache Society (IHS) criteria and the criteria from Sjaastad and co-workers. Kappa statistics were used: 0.83 between the expert headache neurologists; 0.74/0.73 between the expert anesthesiologist in (head) pain treatment and both expert neurologists respectively; kappa ranged from 0.43 to 0.62 between the other physicians. The results of our 'in vivo' design study show that the reliability in diagnosing CEH, when strictly applying the criteria from Sjaastad and co-workers, is similar to the reliability in diagnosing migraine and tension-type headache according the IHS criteria.