CHICAGO – A proposed definition and diagnostic criteria aim to help physicians deal with the growing number of patients presenting with refractory migraine, Dr. Elliott A. Schulman said at the annual meeting of the American Headache Society.
“[Refractory migraine] is out there, we just haven't defined it,” said Dr. Schulman, noting that the incidence is probably 10%–50% of cases seen in practice. By setting a definition, he said, patients who need greater care can be identified early, a standard of care can be established, the epidemiology can be further studied and clarified, and candidates for novel treatment approaches can be identified for clinical trials.
To address the problem, the society's Refractory Headache Special Interest Section was formed in 2000. In April 2006, the section surveyed all AHS members on a proposed definition of refractory migraine, whether it should be added to the International Classification of Headache Disorders, and for information on some of the best practices used.
Two hundred-twenty members responded, for a response rate of 18%, said Dr. Schulman, a neurologist at Lankenau Hospital, Wynnewood, Pa. More than half the respondents believed that refractory migraine should be defined as occurring more than 15 days a month, that it should be associated with disability, and that a definition should include inadequate response to multiple abortive and preventive medications. Almost 60% said a refractory migraine definition should be added to the ICHD.
The criteria proposed for refractory migraine and refractory chronic migraine, which were unveiled at the AHS meeting, were based on the survey results, a literature review, and collaborative discussions, Dr. Schulman said.
The section proposed the following criteria:
▸ The primary diagnosis is ICHD-II migraine or chronic migraine.
▸ The headaches cause significant interference with function of quality of life despite modification of triggers, lifestyle factors, and adequate trials of acute and preventive medicines with established efficacy. This would include failed adequate trials of preventive medicines, alone or in combination, from two of four drug classes: β-blockers, anticonvulsants, tricyclic antidepressants, and calcium channel blockers, as well as failed adequate trials of abortive medicines, including both a triptan and an intranasal or injectable dihydroergotamine (DHE); and either nonsteroidal anti-inflammatory drugs or combination analgesics.
▸ An adequate trial is defined as an appropriate dose administered typically for at least 2 months or the maximum-tolerated dose.
▸ The following modifiers would be included: with or without medication overuse, as defined by ICHD-II; with significant disability, as defined by a Migraine Disability Assessment Questionnaire score of 11 or higher.
The criteria “are intended to stimulate discussion leading to a consensus on the definition of refractory migraine and refractory chronic migraine for research and clinical purposes,” said Dr. Schulman.
Dr. Morris Levin of Dartmouth University, Hanover, N.H., discussed at least four different options for how refractory migraine could be added to the ICHD classification system: as a new diagnostic chapter; as a subdivision to each current headache chapter; as a modifier to the primary diagnosis, as is done with the DSM-IV used for psychiatric disorders; or as an “axis II” diagnosis, again, as is used in the DSM-IV.
In weighing the pros and cons, Dr. Levin noted that the first option would make for a huge new chapter, which might be impractical. Adding subsections to the primary headache diagnosis is logical but would create new language and many new diagnoses, he said.
The addition of a modifier would least affect the rest of the ICHD, but would add another layer to each patient's diagnosis, said Dr. Levin.
Finally, adding another axis would change the overall ICHD format.
Even so, he said, it is worth trying at least one approach and then field testing it, as that would help provide data and validity to the ICHD classification committee.
Dr. Schulman disclosed that he has received grants, honoraria, advisory board and consultation fees from Merck & Co. and Pfizer Inc., and his institution receives direct pharmaceutical industry support. Dr. Levin has received grants, honoraria, and other fees for consultation and advisory board participation from Elan Pharmaceuticals Inc., Allergan Inc., AstraZeneca, Merck, Pfizer, and Ortho-McNeil Inc. His institution also receives direct pharmaceutical industry support.