Central adjudication in randomised trials refers to the evaluation of outcome data by independent experts, often as part of an outcome adjudication committee. Central adjudication is thought to improve the precision of treatment effect estimates by reducing random error (non-differential misclassification), and in open-label studies adjudication has the potential to limit systematic error (differential misclassification) as adjudicators can always be blinded to treatment allocation.

Central adjudication is common in stroke trials. This aim of this project was to investigate the benefits and costs associated with outcome adjudication in stroke trials. The work included a systematic review, a nested randomised trial of methods for contacting authors when requesting data, a simulation study, a cost analysis, and a re-analysis of a completed stroke trial.

These studies demonstrated that central adjudication of the primary outcome in stroke trials does not alter treatment effect estimates. However, for studies without adequate blinding, a small amount of systematic error has the potential to alter the primary analysis and, in this circumstance, adjudication is important. Given that the cost of central adjudication is not trivial, the potential advantages of adjudication may not outweigh cost and time disadvantages in stroke trials with blinded outcome assessment.