ABSTRACT
The Lan-deMets procedure arises when considering stopping rules for clinical trials. An ongoing trial can be stopped for many reasons, two of which are statistical. The first is that the evidence accumulated so far confirms that the regimen has adequate efficacy. The other reason is that the efficacy is found to be too low to go any further. The latter is said to be stopping for futility. Such appraisal has special appeal for phase II trials where the primary aim is to provide proof of concept in the sense that the regimen has minimum efficacy. Stopping for futility will save the researchers from going through the expensive phase III trial. On the other hand, stopping for efficacy can be applied to both phase II and phase III trials but has special appeal to phase III as it can save substantial time and resources.
