The structure of optimal statin initiation policies for patients with Type 2 diabetes

Lipid abnormalities increase the risk of coronary heart disease (CHD) and stroke in patients with Type 2 diabetes. Statins can be used to treat these abnormalities, but may have adverse side effects. In this article, we consider the optimal timing of statin initiation for patients with Type 2 diabetes. We formulate an infinite-horizon Markov decision process to maximize the patient's quality-adjusted life years (QALYs) prior to the occurrence of the first CHD or stroke event. We describe the state of the process by the patient's lipid ratio levels, and derive structural properties of the resulting optimal stopping time model, including sufficient conditions for the optimality of control-limit policies with respect to patient's lipid ratio levels and age. We use a large clinical data set to parameterize our model and compute optimal treatment policies to demonstrate the clinical implications of our results. We illustrate the importance of individualized treatment factors by estimating the patients' QALY gains using our customized policies rather than current U.S. guidelines.