Selecting participants that raise a clinical trial’s population attributable fraction can increase the treatment effect within the trial and reduce the required sample size

BACKGROUND: Detection of modest but worthwhile treatment effects in randomized controlled trials (RCTs) demands trials of large sample size. Approaches to decreasing required size of RCTs while maintaining power are needed. OBJECTIVE: The epidemiological concept of population attributable fraction (AF(p)) was applied to the population selected for an RCT to assess its role in determining the size of treatment effect and the required sample …