Summary of statistics of baseline seizure rates for treatment and control group subjects included in final analysis.

Baseline rates were estimated using Poisson regression on the observed monthly seizure counts during the baseline year. While attempts were made to minimize differences, the treatment and control group subjects completing the study and included in final analysis differed in baseline seizure rates (rate ratio of 0.84, p = 0.04). This difference in baseline rate was accounted for in the statistical analysis in determining the presence of a treatment effect. Specifically, changes in seizures were determined relative to each group's respective baseline seizure rates, and thus no systematic error was introduced into determining treatment effects. Note that while significant differences in baseline seizures were present as a function of gender and seizure classification, no significant differences in treatment effect was present for these covariates.