Policy Optimization for Personalized Interventions in Behavioral Health

Problem definition: Behavioral health interventions, delivered through digital platforms, have the potential to significantly improve health outcomes through education, motivation, reminders, and outreach. We study the problem of optimizing personalized interventions for patients to maximize a long-term outcome, in which interventions are costly and capacity constrained. We assume we have access to a historical data set collected from an initial pilot study. Methodology/results: We present a new approach for this problem that we dub [Formula: see text], which decomposes the state space for a system of patients to the individual level and then approximates one step of policy iteration. Implementing [Formula: see text] simply consists of a prediction task using the data set, alleviating the need for online experimentation. [Formula: see text] is a generic, model-free algorithm that can be used irrespective of the underlying patient behavior model. We derive theoretical guarantees on a simple, special case of the model that is representative of our problem setting. When the initial policy used to collect the data is randomized, we establish an approximation guarantee for [Formula: see text] with respect to the improvement beyond a null policy that does not allocate interventions. We show that this guarantee is robust to estimation errors. We then conduct a rigorous empirical case study using real-world data from a mobile health platform for improving treatment adherence for tuberculosis. Using a validated simulation model, we demonstrate that [Formula: see text] can provide the same efficacy as the status quo approach with approximately half the capacity of interventions. Managerial implications: [Formula: see text] is simple and easy to implement for an organization aiming to improve long-term behavior through targeted interventions, and this paper demonstrates its strong performance both theoretically and empirically, particularly in resource-limited settings. Funding: The authors are grateful for financial research support from the MIT Sloan Health Systems Initiative. Supplemental Material: The online appendix is available at https://doi.org/10.1287/msom.2023.0548 .