Individual patient data meta-analysis of randomized anti-epilepatic drug monotherapy trials

Meta-analysis may be based on either aggregate data or individual patient d ata (IPD). Three reasons why IPD are desirable for the meta-anlysis of anti -epileptic drug (AED) monotherapy trials are: (1) to undertake a more compl ete analysis of time-to-event outcomes; (2) to investigate the interaction between AED and type of epilepsy; and (3) to undertake re-analysis of the t rial to obtain results for all relevant outcomes. We demonstrate that IPD m eta-analysis is possible in AED research. Problems arose from missing data at four levels: (1) unknown trials; (2) known trials but no IPD supplied; ( 3) known trials but missing outcome data for some individuals within trials ; and (4) known trials but missing covariate data for some-individuals with in trials. Empirical evidence of the reliability of meta-analyses based on aggregate rather than individual patient data is still lacking. Examples of other benefits such projects may bring include: improvements to the design of a new trial in the area,in terms of the sample size considerations, the definition of outcomes and data collection.