Kaplan-Meier analysis on seizure outcome after epilepsy surgery: do gender and race influence it?

ABSTRACT

OBJECTIVE: To evaluate seizure outcome following epilepsy surgery for patients with temporal lobe epilepsy and evaluate is gender and race/ethnicity influence it. METHODS: Data were obtained from the discharge database of the University of Alabama at Birmingham, Epilepsy Center, between 1985 and 2001. The sample consisted of all patients with a primary diagnosis of medically intractable temporal lobe epilepsy (TLE) who underwent anterior temporal lobectomy. Seizure recurrence was tabulated at 7 days, 2 months, 6 months, 1, 2, 3, 4, 5, and 6 years following surgery. Logistic regression analysis was used to model the presence of seizure recurrence after anterior temporal lobectomy for all patients. Kaplan-Meier analysis was done to obtain estimates and 95% CIs of seizure freedom from baseline. Baseline variables--age at surgery, age at seizure onset, sex, side of resection, immediate postoperative seizures, and pathology results--were assessed as potential predictors of each outcome by comparing the survival curves within each variable with a log rank test. RESULTS: Three hundred sixty-eight patients underwent surgical treatment for TLE, mean age of 30.2 years. Thirty-five patients were African American, 43% were men. Immediate postoperative seizures were seen in 23 patients, while seizure recurrence occurred in 27.3% patients within a year after surgery, and in 33.6% within 6 years. Logistic regression results showed no differences between African Americans and whites, between males and females. The occurrence of immediate postoperative seizures was a strong predictor of late seizure recurrence only at 1 year after surgery. CONCLUSIONS: The occurrence of seizures in the immediate postoperative period is a strong predictor of later seizure recurrence. Sex and race/ethnicity do not appear to be predictors of long-term outcome following surgery for temporal lobe epilepsy.