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

PurposeTo 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.MethodsThis 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.ResultsThe 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).ConclusionCompared 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.