The incidence of epilepsy and unprovoked seizures in multiethnic, urban health maintenance organizations

Purpose: Studies of the incidence of epilepsy are limited to a few populati ons in which new cases can be ascertained. Health maintenance organization (HmO) populations were studied to determine the incidence in a multiethnic, urban United States population. Method's: Cases of initial unprovoked seizure disorder or epilepsy while en rolled in an HMO between 1988 and 1994 were ascertained. Ethnicity was obta ined from the medical records and was part of a nested case-control study. Results: There were 197 incidence cases of epilepsy and 275 of initial unpr ovoked seizure diagnosis. The incidence rate in the age range 0-64 years wa s 35.5 per 100,000 for epilepsy and 50.9 for initial unprovoked seizure. Wh en compared with population-based studies, rates were slightly higher in ch ildren younger than 15, similar for the 15- to 24-year age group, but lower for ages 25-64 years. The ethnicity-specific odds ratios for initial unpro voked seizure, by using non-Hispanic white as the referent,were 1.04 (0.73- 1.39) for African-American, 0.97 (0.64-1.48) for Hispanic, and 0.25 (0.08-0 .84) for Asian-American. Conclusions: The lower rate in the HMO population is presumably due to a he althy-worker effect. The ethnicity-specific incidence rates do not differ i n this population.