Abstract
Dear Sir We thank Professor Jes Olesen for his interest in our study. Indeed, like previous questionnaire studies performed in France (1) and recently in the USA (2), we found an important group of subjects with probable migraine according to the 2nd Edition of the International Headache Classification (3).
First, our study was cross-sectional and its design did not allow obtaining data by the prospective use of a diary. The diagnosis of probable migraine was made in the same way as that of strict migraine, using a mailed diagnostic questionnaire. It is clear that the gold standard of headache diagnosis is the direct physician-conducted interview, but our diagnostic questionnaire has been previously validated (4) and used in several previous French surveys to identify migraine and migrainous disorders according to the diagnostic criteria of the 1st Edition of the International Headache Classification (1, 5). We used this questionnaire because the operational diagnostic criteria for probable migraine in the 2nd Edition of the International Headache Classification (3) are identical to those for migrainous disorders in the first one (6). Even if exclusion of tension-type headache is not an operational diagnostic criterion for probable migraine (by contrast to the infrequent and frequent tension-type headache diagnosis that requires the exclusion of episodes fulfilling criteria for migraine without aura), it is right that this methodology made it impossible to exclude formally some patients with probable episodic tension-type headache and it would have been preferable to regard these subjects as having probable migraine and/or probable episodic tension-type headache. Therefore, the aim of our study was not to assess the possible overlap between probable migraine and infrequent and frequent tension-type headache that has been suggested by others (7, 8). In addition, it is unlikely that effective early treatment explains the fact that a short duration was the most frequent cause of a probable migraine diagnosis. Indeed, most (59.6%) of subjects with probable migraine included in our study had waited more than 1 h to treat the last attack and the treatments used were mainly non-recommended treatment of slight effectiveness (64.2% of subjects with probable migraine).