Change in intraindividual ICHD-II headache diagnosis over time: a follow-up of the DMKG headache study.

BACKGROUND Change in headache diagnoses over time within the same individual is not well studied in the adult population. In this study, we prospectively examined the individual variation of migraine and tension-type headache (TTH) diagnoses over time. METHODS As part of the epidemiological Deutsche Migräne und Kopfschmerzgesellschaft (DMKG) headache study, 1312 participants were personally interviewed and 1122 responded to a second mailed questionnaire 2.2 years later. Headaches were assigned to migraine or TTH at two different points in time using the International Headache Classification, ICHD-II. We used broad (definite and probable subtypes) and strict (only definite type) definitions of migraine and TTH. RESULTS Using the broad definition increased the reproducibility of migraine diagnosis from 48.0% to 62.0% and of TTH from 59.0% to 65.0%. A constant TTH diagnosis was related to a higher social status (OR 2.81; 95% CI 1.43-5.53) a higher level of education (OR 1.96; 95% CI 1.00-3.85) and physical inactivity (OR 2.28; 95% CI 1.16-4.49). A constant diagnosis of definite migraine was associated with severe headache (OR 2.64; 95% CI 0.97-7.21) and frequent use of headache medication (OR 4.73; 95% CI 0.95-23.60). The result that coexisting TTH decreased the likelihood of a constant migraine (OR 0.29; 95% CI 0.10-0.85) is assumed to indicate response variability. CONCLUSIONS In epidemiological studies, definite and probable subtypes should be included in the diagnosis to increase the diagnostic accuracy.