Comparative effectiveness of 10 antiepileptic drugs in older adults with epilepsy

Abstract

Objective: To compare the effectiveness of antiepileptic drugs (AEDs) for use in older adults with epilepsy.

Design: Retrospective review.

Setting: Columbia Comprehensive Epilepsy Center, New York, New York.

Patients: Four hundred seventeen outpatients 55 years and older newly taking any of the 10 most commonly prescribed AEDs between 2000 and 2005.

Main outcome measure: The percentage of patients who remained taking the AED for 12 or more months (12-month "retention"). We also measured efficacy (12-month seizure freedom) and adverse effects leading to dose change. Retention and seizure-freedom rates were analyzed by pairwise comparisons using chi(2) for the overall group and patients with refractory and nonrefractory disease as well as patients newly taking their first AED.

Results: The 10 AEDs newly taken by 10 or more patients were analyzed. There were no significant non-AED predictors of retention. Without controlling for severity, lamotrigine had the highest 12-month retention rate (79%), significantly higher than carbamazepine (48%), gabapentin (59%), oxcarbazepine (24%), phenytoin (59%), and topiramate (56%). The retention rate for levetiracetam (73%) was second highest and significantly higher than carbamazepine and oxcarbazepine. Oxcarbazepine had the lowest retention rate, significantly lower than all other AEDs. Lamotrigine had the highest 12-month seizure-freedom rate (54%), followed by levetiracetam (43%). When stratified into patients with nonrefractory and refractory disease, relative rates of seizure freedom and retention remained comparable with the overall group. Imbalance, drowsiness, and gastrointestinal symptoms were the most common intolerable adverse effects.

Conclusion: In this study of older adults with epilepsy, lamotrigine was the most effective AED as measured by 12-month retention and seizure freedom, with levetiracetam a close second. Oxcarbazepine was consistently less effective than most other AEDs.