RESULTS: For the primary outcome measure of retention at 12 months, there was a statistically significant (p=0.0002) overall difference between the treatment groups (lamotrigine=55.8%, gabapentin=49.0%, and carbamazepine=35.5%). The paired comparisons indicated significant differences between lamotrigine and carbamazepine (p<0.0001) and gabapentin and carbamazepine (p=0.008). Consideration of reasons for early terminations indicates significant overall differences (p=0.001) between treatment groups for early terminations due to adverse events (lamotrigine=12.1%, gabapentin=21.6%, and carbamazepine=31.0%. There were significant paired comparisons for lamotrigine vs carbamazepine (p<0.0001) and lamotrigine vs gabapentin (p=0.015). There were no differences between the treatment groups for percent of patients seizure free at 3, 6, and 12 months or for the time to first, second, fifth, or tenth seizure (all p>0.05). When individual adverse events during the first 12 months on study drug were considered, it was seen that more gabapentin patients had significantly more weight gain, severe weight gain (>18 pounds), and water retention than patients on either lamotrigine or carbamazepine. Hypersensitivity (rash of any degree) occurred more frequently with carbamazpine than with lamotrigine (p=0.007). The overall conclusion is that lamotrigine and gabapentin should be considered as initial therapy for older patients with newly diagnosed seizures.