The classification of chronic daily headache in adolescents--a comparison between the second edition of the international classification of headache disorders and alternative diagnostic criteria.

OBJECTIVES: To compare the second edition of the International Classification of Headache Disorders (ICHD-2) and the Silberstein-Lipton (S-L) criteria in the classification of adolescents with chronic daily headache (CDH).

METHODS: We reviewed the clinical records and the headache diaries of 170 adolescents (13 to 17 years) seen between 1998 and 2003 at a headache center. Relevant information was transferred to a standardized form that included operational criteria for the ICHD-2. CDH subtypes were classified according the criteria proposed by S-L into transformed migraine (TM) with (TM+) and without medication overuse (TM-), chronic tension-type headache (CTTH), new daily persistent headache (NDPH), and hemicrania continua (HC).

RESULTS: From the 69 patients with TM- according the S-L criteria, most (71%) could be classified as chronic migraine (CM), while a minority of patients required a combination of diagnosis, mainly migraine and CTTH (14.4%). Of the patients with TM+, just 39.6% met the criteria for probable CM (PCM) with probable medication overuse (PMO). If instead of 15 migraine days per month, we considered 15 or more days of migraine or probable migraine, 84% of the subjects with TM- and 68.7% of those with TM+ could be classified. Of the 27 subjects classified as NDPH without medication overuse according to the S-L system, the majority (51.2%) were also classified as NDPH according the ICHD-2. Interestingly, three (11.1% of the subjects with NDPH without medication overuse) were classified as CM in the ICHD-2 because these patients had an abrupt onset of 15 or more days of migraine per month. All patients with NDPH with medication overuse according to the S-L criteria required a combination of diagnoses in the ICHD-2. All subjects with CTTH received a single diagnosis in both classification systems.

CONCLUSIONS: (i) Among adolescents with TM, the majority (58.1%) could be classified as CM, according to the ICHD-2. These results were driven by TM without medication overuse. (ii) If the ICHD-2 criteria for CM are revised to require 15 days of migraine or probable migraine, the proportion of patients with TM- who meet the criteria for CM increases from 71% to 84%; for TM+, the proportion with probable chronic migraine and PMO increases from 30% to 68%. (iii) About half of the patients with NDPH according to the S-L criteria have too many migraine features to meet ICHD-2 criteria for NDPH.