Abstracts

Little is known to guide the post-surgical pharmacologic management of patients who become seizure-free. In a multicenter study of resective surgery patients who attained a [ge]1 year remission, we quantified the relapse risk after tapering AEDs and studied potential predictors of post-tapering relapse. Tapering was at the discretion of the physician or patient. Survival methods were used for analysis. Tapering was treated as a time dependent covariate. Change in relapse rates after reduction of AEDs was estimated. Of 396 surgical patients, 299 (75.5%) had [ge]1 year remission of whom 171 (57.2%) tapered AEDs. Of those who tapered, 49 (28.7%) were taking one, 112 (65.5%) two, and 10 (5.9%) three different AEDs. Relapses occurred in 46 patients, 32 were still tapering at the time of relapse. The relapse risk was 0.06 (95%CI 0.02, 0.10), 0.13 (0.07, 0.18), and 0.24 (0.17, 0.31) at 6m, 1y and 2y after the first reduction. On bivariate analysis, this was lower than the risk in seizure-free patients who never tapered AEDs: 0.13 (0.07, 0.19), 0.27 (0.18, 0.35), 0.34 (0.25, 0.43) at 6m, 1y, and 2y after remission (p=0.002). Those who tapered, however, were more likely to have remitted immediately after surgery (no seizures since hospital discharge) than those who did not taper (78% vs 52%, p[lt]0.0001). This factor was also an important correlate of relapse. After adjustment for immediate remission, tapering AEDs (as a time-dependent covariate) was associated with a small nonsignificant increase in relapse rate (Rate Ratio=1.28, p=0.25). Of many factors examined, only timing of remission was associated with relapse. The risk two years after first tapering was 0.42 for delayed and 0.20 for immediate remission (p=0.01). Thirty (17%) of individuals who tapered the first AED did so on their own without consulting their physician. This did not influence the risk of relapse. Currently 53 individuals are completely AED- and seizure-free. They represent 13% of the entire cohort, 18% of those seizure-free, and 33% of those who tapered AEDs. Relapses occur in about a quarter of seizure-free surgical patients who taper drugs. Tapering is associated with a small nonsignificant increased risk of relapse; however those who do and do not taper vary on prognostic factors such as timing of remission and other factors yet to be identified. Further investigation into specific clinical factors such as post-operative EEG, underlying pathology, and extent of resection is needed to inform a rational approach to post-surgical drug management of seizure-free patients. (Supported by NIH-NINDS R01-NS32375)