Predicting the Duration of Sequential Survival Studies

Interim analyses are a common feature of clinical trial design, especially for large trials in high mortality conditions such as cancer or cardiovascular disease in which the primary endpoint is often the survival time from randomization to death. A plan for a series of interim analyses in which the criteria for stopping are specified in advance is known as a sequential design, and can be constructed to prevent patients from being randomized to an evidently inferior treatment and avoid continuation of a trial that is obviously futile.