Objective: We conducted indirect comparisons of the relative efficacies of clobazam, felbamate, lamotrigine, topiramate, and rufinamide as adjunctive treatments for patients with Lennox-Gastaut syndrome (LGS). Background It is not feasible to make direct comparisons of treatments for LGS without head-to-head studies. Design/Methods: We compared Phase III clobazam results in LGS 1 with RCT results of approved adjunctive LGS therapies from a 2009 Cochrane Review. 2 One of two lamotrigine studies in the Cochrane Review was not included, since randomization methodology for the published study was unclear. Since all 5 studies in our analysis, including the clobazam trial, employed these drugs with adjunctive therapy vs. placebo plus adjunctive therapy, we used traditional, pair-wise indirect comparisons to evaluate clobazam vs. the other drugs. As trial outcomes were not identical, we transformed primary endpoints into effect sizes (using Cohen9s d ). Typical interpretations of Cohen9s d results are: d d d d , large change. Results: High-dosage clobazam (1.0 mg/kg/day) had the greatest effect size, followed by medium-dosage clobazam (0.5 mg/kg/day), and rufinamide. According to Cohen9s d interpretation, effect size (0.80) for high-dosage clobazam was important. Medium-dosage clobazam and rufinamide had d -values >0.50, indicating a moderate clinical effect vs. placebo. Comparisons of numbers of total and drop or tonic-clonic seizures also supported the greater effect of high-dosage clobazam. Because of the few studies in the analysis, however, no results achieved statistical significance. Conclusions: High- and medium-dosage clobazam was estimated to be more efficacious than other LGS treatments. Our analysis relied on published data and could not draw on direct head-to-head data of clobazam with alternatives. Further comparative research is ongoing to assess the usefulness of clobazam for LGS. 1 Ng YT, et al. Neurology . 2011;77:1473–81. 2 Hancock EC, et al. Cochrane Database Syst Rev . 2009;8:CD003277. Supported by: Lundbeck SAS. Disclosure: Dr. Cramer has received personal compensation for activities with Bial, Eisai Inc., Sepracor, and UCB Pharma. Dr. Sabin has received personal compensation for activities with Lundbeck SAS as an employee. Dr. Gani has received personal compensation for activities with Lundbeck Research USA, Inc. an employee. Dr. Francois has received personal compensation for activities with Lundbeck Research USA, Inc.