Sample size
RECRUITMENT
We used a Bayesian sequential design to monitor recruitment [Effect: Harm: Futility: For the effect and harm criteria, we used a standard normal prior for covariates (mean = 0, SD = 1) and a slightly wider prior was used for the futility criterion (mean = 0, SD = 2). The criteria are targets; thus, at each interim analysis, we evaluated each target for each covariate and decided to continue or stop recruitment. Note that this Bayesian approach allows us to look at the data an unlimited number of times without worrying about multiplicities and error rates, as would be necessary using a frequentist approach. Also, since no fixed sample size is prespecified, we reduced the risk of stopping both too early and too late [