Estimating the incidence of first unprovoked seizure and newly diagnosed epilepsy in the low-income urban community of Northern Manhattan, New York City

Purpose : To estimate the incidence and mortality associated with first unprovoked seizure or newly diagnosed epilepsy in a low-income, predominantly Hispanic community in Northern Manhattan, New York City.
Methods : We performed a population-based study to determine the incidence of first unprovoked seizure or newly diagnosed epilepsy. Participants were Northern Manhattan residents seen at area hospitals and nursing homes between 2003 and 2005. Cumulative probability of mortality and standardized mortality ratios (SMRs) were also calculated.
Results : Among 209 incident cases identified, 123 (58.9%) presented with an incident single unprovoked seizure. A total of 138 (66.0%) participants were Hispanic and 94 (45.0%) had a median household income under $15,000/year. The overall age and sex-adjusted incidence of all unprovoked seizures was 41.1 (95%CI = 35.4–46.8) per 100,000 person-years. Higher incidence was observed in low-income groups. Incidence among Hispanics was similar to that of non-Hispanic whites and non-Hispanic blacks. The cumulative probability of mortality was 17% (95%CI = 12–24%) by 3 years after diagnosis and was significantly greater in females and in those with an identified etiology. SMRs were significantly increased for all groups with respect to age, Hispanic ethnicity, middle and high income, partial seizure type, and remote symptomatic etiology. Idiopathic/cryptogenic and progressive symptomatic etiologies, low income, gender, and non-Hispanic ethnicity were not associated with a significantly increased SMR.
Conclusion : Incidence of first unprovoked seizure or newly diagnosed epilepsy did not differ by race-ethnicity. Although lower income was associated with higher incidence, higher income was associated with an increased SMR. Future research should examine reasons for differential incidence by income.