Estimands - Recent discussions and advances
Estimands have recently become an increasingly important issue when designing Clinical Trials submitted to Regulatory Authorities. In October 2014, the Steering Committee of the International Conference on Harmonization endorsed the formation of an expert working group to develop an addendum to the International Conference on Harmonization E9 guideline ("Statistical Principles for Clinical Trials"). The addendum will focus on two topics involving randomized confirmatory clinical trials: estimands and sensitivity analyses. Both topics are motivated, in part, by the need to improve the precision with which scientific questions of interest are formulated and addressed by clinical trialists and regulators, specifically in the context of post-randomisation events such as use of rescue medication or missing data resulting from dropouts. In this talk I will introduce a brief history of the discussions around estimands, highlight the key concepts and ideas and how they have evolved over time. I will also reflect on how such ideas may be useful in other areas such as epidemiology, and also what lessons already learnt in these areas might inform the discussions moving forward.