PHILADELPHIA—Patients with chronic migraine consult physicians for headache and receive headache subtype diagnoses at low rates, researchers reported at the 66th Annual Meeting of the American Academy of Neurology. Approximately 36% of patients who meet criteria for chronic migraine and consult a headache specialist receive a diagnosis of chronic migraine. Of patients with the disease who consult a nonheadache specialist, about 16% receive a diagnosis of chronic migraine.

These low rates of appropriate diagnosis are “a barrier to optimal care, as diagnosis is necessary for designing an optimal treatment plan, which may include diagnosis-specific treatments,” said Dawn C. Buse, PhD, Associate Professor of Neurology at Albert Einstein College of Medicine in the Bronx, New York.

Patients’ Awareness of Certain Preventive Treatments Was Low
Dr. Buse’s findings come from the Chronic Migraine Epidemiology and Outcomes (CaMEO) study, a prospective, web-based cohort study based on the collection of longitudinal and cross-sectional data. A total of 16,789 individuals who met modified International Classification of Headache Disorders-3b (ICHD-3b) criteria for migraine enrolled in the study. Beginning in September 2012, Dr. Buse and colleagues e-mailed respondents and invited them to participate in multicomponent web-based survey modules. A total of 1,476 respondents screened positive for chronic migraine. Respondents answered questions about health care visits; diagnoses; treatments; and knowledge, attitudes, and behaviors that might be barriers to optimal care.

Diagnoses of migraine and chronic migraine were made more frequently by headache specialists than by other health care practitioners. But most respondents with chronic migraine did not receive a diagnosis of chronic migraine, even among those who consulted headache specialists. Patients who see only a nonprescribing health care practitioner are the least likely to have ever received a diagnosis of migraine; chronic migraine; or chronic migraine, transformed migraine, or chronic daily headache. More respondents with chronic migraine were currently consulting a nonprescribing health care practitioner than a headache specialist.

Approximately 34% of respondents diagnosed with chronic migraine reported using a preventive pharmacologic treatment for migraine. Respondents with chronic migraine who consulted a headache specialist were highly likely (82%) to receive a preventive treatment. About 80% of respondents with chronic migraine were aware of some form of preventive therapy, but awareness varied by type of treatment. Nearly 63% of respondents with chronic migraine had heard of the technique of avoiding triggers, but 17.4% were aware of the possibility of receiving periodic injections.

Knowledge and use of empirically supported nonpharmacologic methods of migraine prevention were low among patients who consulted a headache specialist and very low among patients not under the care of a headache specialist. “These data demonstrate gaps in the diagnosis, treatment, and knowledge of individuals with chronic migraine in the United States and offer opportunities for improvement in care,” said Dr. Buse.

New Chronic Migraine Screening Tool Has High Accuracy
To improve the diagnosis of chronic migraine, Dr. Buse and colleagues developed the Identify Chronic Migraine screening tool. She and her colleagues drafted a list of 19 candidate test items, based on a review of existing screening instruments and suggestions from a panel of eight international headache experts. The panel then helped the researchers create a 16-item draft questionnaire from the 19-item list.

The researchers subsequently conducted cognitive debriefing interviews with 10 patients with chronic migraine. The investigators also administered the draft screening tool to an online research panel of self-identified individuals with severe headache to determine the composition of the final group of screeners. In addition, Dr. Buse and colleagues used a two-stage screening method to identify migraine among people with severe headache and to screen for chronic migraine among individuals with migraine.

The panel of headache experts selected a final set of 16 items for testing in the cognitive debriefing interviews, which confirmed that the items were well understood and judged to be relevant. Item response theory modeling resulted in a 12-item screening tool. The first-stage migraine screening factor had 98% classification accuracy, compared with ICHD-3b migraine classifications. The second-stage chronic migraine screening factor had 96% classification accuracy, compared with ICHD-3b chronic migraine classifications.

The final screening tool included questions about the disruptiveness of headaches such as “How often did you feel fed up or irritated because of your headaches?” Other items asked about disability related to headaches (eg, “On how many days did you miss work or school because of your headaches?”). Six questions elicited information about headache symptoms, including “How often was the pain worse on just one side?”

The researchers plan to develop item-scoring criteria for the screening tool, said Dr. Buse. They also plan to compare screening diagnoses with “gold-standard” clinical diagnoses using structured interviews conducted by headache experts.

—Erik Greb

Chronic Migraine May Be Underdiagnosed and Undertreated