A "dynamic treatment regime," also referred to as an "adaptive treatment strategy," is a set of formal "rules" that dictate how to make decisions on treatment of a patient over time. Each rule corresponds to a decision point at which a decision is to be made on changing, modifying, augmenting, stopping, or starting treatment, and takes as input information on the patient up to that point. Based on this information, the rule outputs the next treatment action. Thus, dynamic treatment regimes are algorithms that allow sequential treatment decisions to be "individualized" through a principled, evidenced-based set of rules that attempt to operationalize and systematize the way clinicians manage patients in practice.
We first introduce the notion of a dynamic treatment regime. We then describe a formal framework for developing and studying dynamic treatment regimes.