Increasing incidence of medically recognized migraine headache in a United States population

Objective: To investigate trends in the incidence of medically recognized migraine in Olmsted County, Minnesota over approximately a decade. Methods: The authors used the records-linkage system of the Rochester Epidemiology Project to identify individuals whose records included any diagnostic rubric related to headache for the 3-year period 1979 through 1981 and the 2-year period 1989 through 1990. A nurse abstracter and a neurologist (J.W.S.) reviewed the complete history of each potential case and assigned a diagnosis using the International Headache Society classification (IHS, modified). Only patients who consulted a doctor for their headache and had their initial visit for migraine within the study years were considered as incident cases. Results: The incidence of medically recognized migraine increased in female subjects between the 1979-through-1981 period and the 1989-through-1990 period for all ages, but particularly among those who were aged 10 to 49 years. The peak incidence rate at age 20 to 29 years increased from 634.5 new cases per 100,000 person-years in 1979 through 1981 to 986.4 in the 1989-through-1990 period (absolute increase 351.9; relative increase 56%). The rise in incidence in female subjects was most sizable for migrainous disorder (IHS code 1.7); smaller increases were noted for migraine without aura and with typical aura. Only a slight absolute increase in migraine incidence rates was observed in male subjects, restricted to those 10 to 19 years of age (absolute increase 174.7; relative increase 89%). Conclusions: Although the incidence rates reported here are restricted to patients who consulted a doctor for their headache, the authors suggest that the incidence of migraine has increased over time in female subjects, especially those of reproductive age. The increase was most pronounced for migrainous disorder. Incidence rates were more stable in male subjects over time.