New use of anticonvulsant medications among children enrolled in the Tennessee Medicaid program

Objective: To describe the new use of anticonvulsant medications among children enrolled in the Tennessee Medicaid program. Design: A retrospective cohort study. Patients: New users of anticonvulsant medications in 1992 were identified from the 206098 children (aged 0-18 years) enrolled continuously for 12 months in the Aid to Families With Dependent Children program or foster care program of Tennessee Medicaid. Main Outcome Measures: New users were categorized according to the diagnosis codes of health care encounters occurring 90 days before to 90 days after the first anticonvulsant prescription was filled as having diagnoses consistent with (1) epilepsy or convulsions, (2) neonatal seizures, (3) central nervous system disease, (4) no epilepsy diagnoses but diagnoses for which anticonvulsants might appropriately be used (jaundice, headaches, or psychiatric disorders), or (5) no diagnoses for which an anticonvulsant might appropriately be used. The children in each group were described according to sociodemographic variables, with logistic regression used to analyze variations in the subsequent filling of anticonvulsant prescriptions. Results: Of 647 children continuously enrolled in the Tennessee Medicaid program who were new anticonvulsant users in 1992, 58% had at least 1 health care encounter coded as epilepsy or convulsions, 2% had a diagnosis of neonatal seizures, 8% had central nervous system diagnoses, 16% had specific nonepilepsy diagnoses (jaundice,headache,or psychiatric diagnosis), and 16% had no diagnoses for which anticonvulsants might appropriately be prescribed. For children with epilepsy diagnoses, white race (P=.002) and undergoing tests (P<.001) were independent predictors of a child filling 6 or more prescriptions in the year following the first prescription. Conclusions: A large proportion of new users of anticonvulsants among children enrolled in the Tennessee Medicaid program received these medications for indications other than epilepsy. For children with epilepsy diagnoses, there was considerable variation in the subsequent filling of prescriptions. Further analysis of these variations in practice will allow for the development of policies that will maximize benefit for children who need anticonvulsant therapy, while diminishing unnecessary exposure to potentially toxic drugs for children who do not.