Sample size estimation and re-estimation of cluster randomized controlled trials for real-time feedback debriefing and retraining system of cardiopulmonary resuscitation for out-of-hospital cardiac arrests

摘要

BackgroundIn cluster randomized controlled trials (RCTs) for emergency medical services (EMS) system, we encounter the situation that the actual cluster size and ratio of allocated patients between two groups eventually differ from those used for sample size estimation because of the nature of patient enrollment. In such trials, estimations of effect size of test intervention and intra-cluster correlation coefficient (ICC) used for sample size estimation are also difficult. To improve efficient management on clinical cluster RCTs, we need to understand the effect of such inconsistencies of the design parameters on the type I error rate and statistical power of testing.