Abstracts

Rationale: Selection of antiepileptic drugs (AEDs) for individual with HIV/AIDS who receives antiretroviral therapy (ART) is extremely challenging. Previous studies suggest that interaction of ART and AEDs, especially enzyme inducing AEDs (EI-AEDs), can lead to an increment of viral replication and the emergence of resistance. It, however, remains unknown whether patients with epilepsy and HIV/AIDS receive appropriate AEDs. We examined the pattern of concurrent use of ART and AEDs in a cohort of epilepsy patients with HIV/AIDS to assess whether optimal choice of AEDs are prescribed.Methods: We analyzed claims data from the Ohio Medicaid Database between 1992 and 2008. Our epilepsy cohort consisted of patients who were (1) at least 18-year-old; (2) at least one visit of epilepsy diagnosis (ICD-9-CM: 345.xx) or at least two visits of non-febrile convulsions (ICD-9-CM: 780.3 or 780.39); (3) at least one AED dispensing claim; (4) at least two years of Medicaid enrollment prior to epilepsy diagnosis. We excluded individuals who had gaps in enrolled months of 20% or more, who enrolled in managed care, the Medicare program, or the spend-down program. The incident cases of epilepsy were identified between 1994 and 2006. We documented whether the patients had diagnosis of HIV/AIDS (ICD-9-CM: 042) at the time of epilepsy diagnosis or subsequently. Pharmacy dispensing claims during the first 12 months after the diagnosis of epilepsy or HIV/AIDS were analyzed. In addition, we assessed whether the patients received combinations of AED and ART with known pharmacokinetic drug-drug interactions that resulted in reduction of AED level.Results: There were 5,430 patients in our epilepsy cohort and 60 patients had both epilepsy and HIV/AIDS. Of 60 patients, 47 patients had HIV/AIDS prior to epilepsy diagnosis and 36 patients were taking ART. Among 47 patients, 28 (59%) patients were prescribed EI-AEDs, 8 (17%) patients were on valproate, and 14 (30%) patients were on AEDs that did not affect CYP-450. Between 1994 and 2006, there were 13 newly diagnosed HIV/AIDS. At the time of HIV/AIDS diagnosis, close to 70% of the patients were on EI-AEDs and approximately 30% were on AEDs that did not affect CYP-450. Multivariate analysis showed no association between age, race, or gender and the receipt of appropriate AEDs. The minority of patients (15%) were prescribed combinations of AED and ART with known drug-drug interactions that decreased AED level and about two third of these patients had epilepsy-related ER visits and/or inpatient hospitalizations.Conclusions: Despite evidences that EI-AEDs are associated with high rate of virologic failure, the majority of patients with epilepsy and HIV/AIDS are prescribed EI-AEDs and ART. Interestingly, only small number of patients receive combinations of AED and ART with known drug-drug interactions that reduce AED level. Whether appropriate dose adjustment and monitoring of AED and ART levels are performed in patients who receive EI-AEDs and ART remain to be determined.