TY - JOUR T1 - Bayesian Structural Time Series on State-Level EHR Aggregates: The Optimal Method for Estimating Telemedicine's Causal Impact on Diabetes Control AU - Thabo Nkosi AU - Lerato Molefe AU - Sipho Dlamini AU - Ayanda Mokoena AU - Kabelo Ndlovu JF - Journal of Artificial Intelligence for Healthcare Systems JO - J. Artif. Intell. Healthc. Syst. SN - 3149-8981 Y1 - 2024 VL - 3 IS - 2 SP - 93 N2 - Telemedicine expanded rapidly during COVID-19 as Medicare and states relaxed long-standing restrictions. Diabetes outcomes (HbA1c, blood pressure, LDL cholesterol) are routinely tracked in EHRs, yet causal evidence that telemedicine improves these outcomes remains limited. Pre-post analyses cannot separate telemedicine effects from confounding time trends such as seasonality and pandemic-related changes, while randomized state-level policy trials are infeasible. This leaves a key evidence gap for policy decisions. Bayesian structural time series (BSTS) using state-level EHR aggregates is the most suitable approach for causal inference, constructing counterfactual outcomes from similar donor states. BSTS accounts for trends, seasonality, and autocorrelation, and uses synthetic control principles to reduce confounding. It also provides uncertainty estimates and works with routinely collected aggregate data. Policymakers should require BSTS-based evidence before making telemedicine coverage permanent. Researchers should apply these methods to existing policy variation and share data and code. States should build routine EHR-based monitoring systems for diabetes outcomes. Causal evaluation of telemedicine is feasible now using existing data and methods. Relying on pre-post studies or waiting for randomized trials delays actionable evidence needed for policy decisions. UR - https://cirpublications.com/t925263662 ER -