Comparison of the retention rates between carbamazepine and valproate as an initial monotherapy in Chinese patients with partial seizures: A ten-year follow-up, observational study

Purpose: To compare the long-term retention rates of the two most commonly prescribed antiepileptic drugs (AEDs), carbamazepine (CBZ) and valproate (VPA) as an initial monotherapy in Chinese patients with partial seizures. Methods: This is a retrospective, observational study in a tertiary epilepsy centre. Overall, 584 patients were followed during a ten-year period. Kaplan-Meier survival analysis was used to estimate the cumulative probability of retention. Cox proportional hazard model was used to analyze the risk factors for retention rate. Results: The calculated retention rates estimated by Kaplan-Meier survival analysis showed no difference between CBZ and VPA (p = 0.074). During the time period from the first six months to two years, the lack of efficacy (LE) that led to drug discontinuation was 10.7% for CBZ compared to 4.5% for VPA (p = 0.004). The adverse effects (AEs) that led to discontinuation was 2.4% for CBZ compared to 6.3% for VPA (p = 0.025). Clinical control that led to discontinuation was 15.9% for CBZ compared to 7.5% for VPA (p = 0.001). The five-year remission rate was higher in the CBZ group (33.3%) than in the VPA group (23.2%, p = 0.006). Yet in the complex partial seizure subgroup, there was no significant difference between the two drugs (p = 0.61). Conclusion: Compared with VPA, patients treated with CBZ were more likely to discontinue treatment for LE, and were less likely to discontinue for AEs; however, the two differences above only occurred in the time period between the first six months to two years of treatment. Long-term treatment with CBZ appeared to be more effective in terms of five-year remission and clinical control than VPA. (C) 2010 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.