Abstracts

To investigate the difference in outcomes and compare the incidence of adverse events (AEs) in a commercially-insured epileptic patient population initiating levetiracetam (LEV) or topiramate (TPM). A retrospective cohort analysis of patients diagnosed with epilepsy was conducted using a large US medical and pharmaceutical claims database. Patients without any LEV or TPM prescription during a 6-month baseline period were classified into mutually exclusive treatment groups based on their first LEV or TPM medication prescription. A minimum 3-month duration of follow-up was required. All relevant claims between July 2001 and September 2003 were considered. Patients were matched on a 1:1 basis by seizure type, mono versus adjunctive therapy and propensity score adjusted for clinical and demographic characteristics. Differences in outcomes (medications, outpatient and inpatient care) were tested by univariate techniques. The risk of adverse events at one year of follow-up was compared across treatment groups using Cox proportional hazards models controlling for confounding covariates. A total of 1454 and 1297 patients receiving LEV and TPM respectively met the study inclusion criteria. Matching resulted in the selection of 822 patients in each LEV and TPM group. Both groups were comparable with respect to clinical and demographic characteristics: mean age [sim]31 years, [sim]64% female, 70% generalized seizures, 66% adjunctive therapy, mean propensity score = 0.53. During follow-up period, LEV was prescribed more often than TPM (mean/patient/year: 12.1 vs 8.5). Furthermore, the annualized mean number of physician office visits was significantly lower in LEV than in TPM (15.3 vs 18.6, p=0.004) as well as the mean number of medications (excluding anti-epileptic drugs) per patient per year (19.5 vs 25.9, p[lt]0.001). LEV also showed lower use of other outpatient visits, while use of diagnostic tests and inpatient services was lower in TPM. The rate of patients who did not experience any AE during the follow-up period was 52.6% for LEV versus 47.3% for TPM. Time to first AE was significantly longer for LEV than for TPM (Hazard Ratio: 0.83, p=0.006). Mean duration to first AE was 85 days for LEV versus 73 days for TPM. In a commercially-insured setting, treatment with LEV was associated with a significantly lower use of common health care services compared to TPM. Data suggest better adherence to treatment with LEV. In addition, LEV patients were significantly less likely to experience AEs than TPM patients. (Supported by UCB Pharma S.A.)