PREDICTORS OF OUTCOME OF EPILEPSY SURGERY - MULTIVARIATE-ANALYSIS WITH VALIDATION

Purpose: To identify predictors of outcome of epilepsy surgery, using the Duke experience, applying multivariate analysis and validation tec hniques. To compare the results of different modeling algorithms. Few previous studies have reported multivariate analysis, or validated the ir results. Methods: Records of 116 patients with focal resections for intractable epilepsy from January 1, 1980 through June 30, 1989 were analyzed. Primary outcome variable was patient's condition in second p ostoperative year: seizure free (except auras), or not. Three predicto rs of biologic interest were specified a priori for confirmatory analy sis. Additional predictors were considered within exploratory analysis . Logistic regression techniques were applied to assess relations with pre- and postoperative predictors, Internal validity was assessed by repeated random selection of training and validation samples, used in conjunction with bootstrap techniques. Results: By using multivariate analysis, percentage of epileptic EEG activity arising from the site o f resection and either imaging localization or lack of use of invasive monitoring were the only statistically significant preoperative predi ctors for good outcome at 2 years. Presence of seizures within 2 month s of surgery was a significant postoperative predictor for a pour outc ome, Adding more variables did not result in significantly improved mo dels, Use of validation techniques reduced the degree of optimism in t he predictive value of the models. Conclusions: Pooling of data from m ultiple institutions is needed to attain the large sample sizes needed for multivariate analysis with validation.