Sample size determination in clinical trials with time-dependent rates of losses and noncompliance

Sample size determination is an important part of planning for clinical trials. During the course of a typical clinical trial, people are lost because of competing risks, noncompliance, and the like. Event rates available to the trial designers usually do not take these losses into consideration so that adjustment of these rates is necessary for sample size calculation. This article presents a method of adjusting such rates in the presence of time-dependent rates of losses, noncompliance, and the like. Lag in the effectiveness of medication is also considered.