A post hoc evaluation of a sample size re-estimation in the Secondary Prevention of Small Subcortical Strokes study.

Background/aims:The use of adaptive designs has been increasing in randomized clinical trials. Sample size re-estimation is a type of adaptation in which nuisance parameters are estimated at an interim point in the trial and the sample size re-computed based on these estimates. The Secondary Prevention of Small Subcortical Strokes study was a randomized clinical trial assessing the impact of single- versus dual-antiplatelet therapy and control of systolic blood pressure to a higher (130–149 mmHg) versus lower (<130 mmHg) target on recurrent stroke risk in a two-by-two factorial design. A sample size re-estimation was performed during the Secondary Prevention of Small Subcortical Strokes study resulting in an increase from the planned sample size of 2500–3020, and we sought to determine the impact of the sample size re-estimation on the study results.Methods:We assessed the results of the primary efficacy and safety analyses with the full 3020 patients and compared them to the results that would have been ...