The use of migraine preventive medications among patients with and without migraine headaches.

The aim was to describe the use of and adherence to migraine preventives among insured patients meeting the International Classification of Headache Disorders, 2nd edn (ICHD-II) criteria for migraine headaches. A retrospective, case-control study was conducted using data from a telephone interview linked with health insurance claims data. Subjects were health plan enrollees aged 18-55 years who had incurred at least one encounter between June 2000 and November 2001. Interview responses were used to identify cases meeting the ICHD-II criteria for strict and probable migraine and a random sample of controls. Pharmacy claims data were used to construct measures of use and adherence. Differences in outcomes by adherence status were evaluated using generalized linear models. We identified 2517 cases and 941 controls. Among cases, the prevalence of antidepressant use was 4%, anticonvulsant use was 1.9%, antihypertensive use was 8.9%. Combined use was 13.4% among cases and did not differ significantly from that observed among controls (12.4%). Mean adherence rate between the first and last dispensing during the year was high (88%) and did not differ by migraine status. When the entire 12-month period is considered, adherence was substantially lower (56%). Patients who were adherent between dispensings reported significantly less migraine-related disability and incurred higher prescription drug costs, but did not differ in their total medical care costs. Patients with migraine are unlikely to be users of preventive medications. Among users, few are taking preventive medications continuously. Patients with migraine-especially those without a medical diagnosis for migraine or headaches-are not receiving the benefits available from existing pharmacotherapy options.