Improving Probabilities of Correct Interim Decision in Population Enrichment Designs.

Choice of target population is an essential part at the design stage of clinical trials. Data from earlier clinical development might suggest that the treatment is more effective in a subpopulation, but there might not be enough evidence to restrict the target population upfront. Adaptive designs allow modification of the target population based on interim data. Decision for modification should be based on objective decision rules. The presented decision rules maximize the weighted probability of correct interim decisions based on prior assumptions. Evaluation of decision rules in the planning phase can improve probabilities of correct interim decision and power.