Prevalence and Incidence of Epilepsy in an Elderly and Low-Income Population in the United States

BACKGROUND AND PURPOSE: The purpose of this study was to estimate the incidence and prevalence of epilepsy among an elderly and poor population in the United States. METHODS: Arizona Medicaid claims data from January 1, 2008 to December 31, 2010 were used for this analysis. Subjects who were aged ≥65 years and were continuously enrolled in any Arizona Medicaid health plans (eligible to patients with low income) for ≥12 months between January 1, 2008 and December 31, 2009 were considered eligible for inclusion in the study cohort. In addition to meeting the aforementioned criteria, incident and prevalent cases must have had epilepsy-related healthcare claims. Furthermore, incident cases were required to have a 1-year "clean" period immediately preceding the index date. Negative binomial and logistic regression models were used to assess the factors associated with epilepsy incidence and prevalence. RESULTS: The estimated epilepsy incidence and prevalence for this population in 2009 were 7.9 and 19.3 per 1,000 person-years, respectively. The incidence and prevalence rates were significantly higher for patients with comorbid conditions that were potential risk factors for epilepsy and were of younger age than for their non-comorbid and older counterparts (p<0.05). The prevalence rates were significantly higher for non-Hispanic Blacks and male beneficiaries than for non-Hispanic Whites and female beneficiaries, respectively (p<0.05). CONCLUSIONS: This patient population had higher epilepsy incidence and prevalence compared with the general US population. These differences may be at least in part attributable to their low socioeconomic status.