Prevalence and Burden of Illness of Migraine in Managed Care Patients

OBJECTIVES: To determine the 3-month prevalence rate of migraine in a health maintenance organization (HMO) population, using a 2-stage screening process and neurologist exam, and to examine the burden of illness associated with both previously diagnosed and previously undiagnosed migraine in this population. METHODS: A migraine assessment was sent to a random sample of 1,000 HMO patients between April 1999 and January 2000. Those screening positive and a random sample of those screening negative for migraine were evaluated by neurologists using a structured diagnostic assessment. Then, those diagnosed to have migraines by the study's neurologists completed a battery of 3 questionnaires, evaluating severity, distress, and impairment. RESULTS: Of 1,000 questionnaires sent, 753 (75.3%) were returned. The estimate of prevalence of migraine in this population ranged from 21.4% (adjusted for response bias) to 27.8% (unadjusted for selection bias). Only 48% of respondents had been previously diagnosed with migraine. The typical migraine caused moderate-to-severe distress in 69%, and 66% had definite or extreme interference in their social or occupational functioning. The average migraineur missed 7.6 hours of work due to migraine in the past 3 months. Previously undiagnosed migraine was associated with substantial impairment, with 58% of responders reporting interference with daily activities and 54% reporting moderate or greater distress. There was no significant difference between previously diagnosed and undiagnosed migraineurs on 3 outcome measures: pain, interference, or days of missed work. A higher proportion of previously diagnosed migraineurs (84%) reported moderate or greater distress compared with undiagnosed migraineurs (54%, P=0.002). CONCLUSIONS: Using a neurologist exam, the researchers found that the prevalence of migraine headaches was higher than previously reported. About one half of migraineurs had been previously undiagnosed. Undiagnosed migraine is associated with significant pain, distress, and dysfunction and is similar in these respects to diagnosed migraine. Increased public education and physician education on migraine are warranted.