A confirmatory trial is an adequately controlled trial where hypotheses are stated in advance and evaluated according to a protocol.
This type of trial may be implemented when it is necessary to provide additional or firm evidence of efficacy or safety.
Of importance in a confirmatory trial is the process of estimating with due precision potential effects attributable to the treatment, the quantity of effects and relating these effects to their clinical significance.
According to the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use: "Confirmatory Trials are intended to provide firm evidence in support of claims and hence adherence to protocols and standard operating procedures is particularly important; unavoidable changes should be explained and documented, and their effect examined.
"[1] Basic outline of the process of a confirmatory trial