SAN DIEGO – People on Medicaid have a high incidence and prevalence of epilepsy, in an order of magnitude greater than that reported in the U.S. general population, results from a large analysis demonstrated.
This indigent population "carries a disproportionate amount of the epilepsy burden and therefore deserves more attention for their health care needs and support services," Dr. Kitti Kaiboriboon said in an interview at the annual meeting of the American Epilepsy Society, where the work was presented.
Dr. Kitti Kaiboriboon
Few studies have shown that people with low socioeconomic status have a higher incidence and prevalence of epilepsy than their counterparts with high socioeconomic status, said Dr. Kaiboriboon, a neurologist in the epilepsy center at University Hospitals Case Medical Center, Cleveland.
"However, no study, to our knowledge, has specifically examined the incidence and/or prevalence of epilepsy in the Medicaid population, which are among the sickest and the poorest group of people in the United States," he said. "They have [a] high incidence and prevalence of chronic medical conditions, some of which are risk factors for epilepsy. The incidence and prevalence of epilepsy in this population are very important for public health planning."
The incidence and prevalence of epilepsy in the general population vary from study to study, he said, but the incidence of epilepsy in the United States usually ranges between 15 and 71/100,000 person-years, while the prevalence usually ranges between 5 and 9/1,000 persons.
Dr. Kaiboriboon and his associates obtained Ohio Medicaid claims data for adults between 1992 and 2006 to identify prevalent and incident cases of epilepsy. Prevalent cases of epilepsy were defined as those that had two or more claims of epilepsy or three or more claims of convulsion and two or more claims of antiepileptic drugs. Each of the diagnosis or pharmacy claims had to be more than 30 days apart. Incident cases of epilepsy were required to have no epilepsy or convulsion claims for at least 5 years before epilepsy was diagnosed. The researchers also determined which subjects had a preexisting disability and/or comorbid conditions including brain tumor, depression, developmental disorders, migraine, schizophrenia, stroke, and traumatic brain injury when at least one of these conditions occurred prior to the onset of epilepsy.
Dr. Kaiboriboon presented findings from 9,056 prevalent cases and 1,608 incident cases of epilepsy. The incidence of epilepsy in the Medicaid population was 360/ 100,000 person-years. "There are about 60 million people in the Medicaid population; you would expect to have 216,000 new cases of epilepsy each year," he said. "We found that the prevalence of epilepsy was 13.2/1,000 persons, which means that there are 792,000 Medicaid beneficiaries with epilepsy," he said. "This is huge."
The researchers found that the majority of Medicaid beneficiaries with epilepsy have preexisting medical and/or psychological conditions, with the most common being depression (773 cases), developmental disorders (436 cases), and stroke (422 cases). They also found that among people with preexisting conditions, people with brain tumor, traumatic brain injury, and stroke have the highest risk of developing epilepsy (risks of 78%, 76%, and 70%, respectively).
Dr. Kaiboriboon acknowledged certain limitations of the study, including the fact that it relied on Medicaid claims data to obtain the incidence and prevalence of epilepsy. "The case ascertainment, therefore, was mainly based on diagnosis codes," he said. "We, however, used very stringent criteria to identify subjects with epilepsy. Also, subjects who in fact had epilepsy but were not actively taking AEDs [antiepileptic drugs] would not be included in the analysis. Because of this, our incidence and prevalence are the estimates for ‘treated’ epilepsy."
The study was funded by the Epilepsy Foundation and by a grant from the National Center for Research Resources. Dr. Kaiboriboon said he had no relevant financial conflicts to disclose.