Sample size
This feasibility study was created to pilot our adaptive trial methods and our study protocol; a sample size was determined based on feasibility of these methods not as a power analysis for effectiveness testing. Sample size for our feasibility enrollment was to mimic our trial allocation on a smaller scale, and pilot the adaptation process between stages. We included at least 10 participants in each arm to test intervention/allocation protocols. Since this trial was aimed at assessing feasibility and was not powered to detect statistical differences in performance of each arm, we continued the PPKAY with the Standard Booster arm in Stage 3 according to hypothesized superiority.