A SIMPLE MEASURE IN DEFINING OPTIMAL STRATA IN CLINICAL-TRIALS

This paper deals with balancing groups with respect to prognostic fact ors in clinical trials, as a means of increasing the power of a study. We use the Mantel-Haenszel statistic to obtain a simple measure for a ssessing the relative efficiency of different factors for stratificati on and to find optimal cutpoints for the given factors. For any availa ble database, the measure can be used to construct optimal strata for a clinical trial. The paper also presents a practical approach for red ucing the number of strata using discriminant regions with a method of assessing the effectiveness of this approach. An example from a large database of severe head trauma patients illustrates the utility of th e measure.