Abstracts

Rationale: About 35% of epilepsy patients are pharmacoresistant. Since 1993 12 new AEDs have been introduced. The most recent studies of AED response occurred before widespread use of the second wave of the new AEDs (levetiracetam, oxcarbazepine, zonisamide, pregabalin, lacosamide) (1,2). They suggested that seizure freedom occurs in ?3% of patients who fail to respond to 3 AEDs or are treated with polytherapy. In the present study, we evaluated the response to AEDs during years 2003-09 in a tertiary epilepsy center. Methods: The charts of all patients evaluated and treated consecutively between 2003-09 at one tertiary epilepsy center were reviewed for response to AED therapy. Epilepsy was classified using ILAE criteria. AED choice was based on estimate of best fit of AED(s) for each patient, using epilepsy type, AE potential, comorbidity, pharmacokinetics, drug-drug interaction and ease of use as choice determinants. Response was defined as seizure freedom for 12 months. Results: 583 patients (367 [63%] F, 216 [37%]M) were evaluated. Mean age was 42 years (range 11-89), mean epilepsy duration 17.5 years (range 1-76). 510 (87.48%) patients had localization related epilepsy (LRE), 73 (12.52%) primary generalized epilepsy (PGE). 237/583 (40.7%) became seizure free, including 195/510 (38.2%) LRE patients and 42/73 (57.5%) PGE patients. 62/510 (12.2%) LRE patients responded to the first AED, 48/510 (9.4%) to the second AED, including both mono- and polytherapy, and 30/510 (5.9%) to the third. 10.9% became seizure free with the use of ?4th AED: 27/510 (5.3%) with the fourth, 9 (1.8%) with the fifth, 7 (1.4%) with the sixth, 8 (1.6%) with the seventh, 3 (0.6%) with the eighth, and 1 (0.2%) with the ninth. 9/73 (12.3%) PGE patients responded to the first AED, 10 (13.7%) to the second, and 13 (17.8%) to the third. 15.1% became seizure free with the use of ?4th AED: 4/73 (5.5%) with the fourth, 3 (4.1%) with the fifth, and 0-2 (0-2.7%) with the sixth-eleventh AEDs. 116/510 (22.8%) of LRE patients responded to monotherapy, 79/510 (15.5%) to polytherapy. 31/73 (42.5%) of PGE patients responded to monotherapy, 11/73 (15.1%) to polytherapy. LRE monotherapy: 38/510 (7.5%) patients responded to LEV, 21 (4.1%) to CBZ, 15 (2.9%) to PHT, 14 (2.8%) to LMT, 12 (2.4%) to VPA, 8 (1.6%) to PB, 3 (0.6%) to GBP and 2 (0.4%) to TPM. LRE polytherapy: 5/510 (1%) each of LRE patients responded to combinations of LEV LMT and LEV TPM, 4/510(0.8%) to VPA LEV, and 3 (0.6%) each to CBZ LMT and to TPM LEV LMT. Response to other combinations was limited to 1-2 patients. PGE monotherapy: 15/73 (20.6%) of PGE patients responded to VPA, 8 (11%) to LEV, and 3 (4.1%) to LMT. Response to other AEDs was limited to 1-2 patients. PGE polytherapy: 11/73 (15.1%) of PGE patients became seizure free on polytherapy, but ?2 patients responded to any one combination. Conclusions: 10.9% of LRE patients and 15.1 % of PGE patients became seizure free after failing 3 AEDs. 15.5% of LRE and 15.1% of PGE patients achieved seizure freedom on polytherapy. AED response may be greater than previously thought with the use of new AEDs.