Thorpe JM, et al. - Researchers linked national Veterans Affairs (VA) and Part D records regarding the use of healthcare services and prescriptions in a cohort of nearly 280,000 veterans who were continuously recruited in VA and Part D and had received ≥ 1 medication through the VA in 2015, in order to assess the correlation of dual prescription use with the prevalence of potentially unsafe medication (PUM) exposure. Among Medicare-eligible older veterans who received a prescription from the VA, 18.9% were dual users and 44.3% were exposed to ≥ 1 PUM. Nearly 50.0% were exposed to any PUM type, including 38.6% to PUM-anticholinergic cognitive burden (ACB), 19.3% to PUM- high-risk medication in the elderly (HEDIS), and 4.4% to PUM- drug combinations with high risk for severe interactions (DDI) in dual users. Dual-use was correlated with increased odds of any PUM exposure and an additional 19.4 days of exposure, according to adjusted results. Dual-use was also correlated with increased odds of PUM-HEDIS, PUM-ACB, and PUM-DDI. PUM exposure was least among VA-only users, and PUM exposure plateaued in veterans who received prescriptions in near-equal proportions from the VA and Part D. Hence, in near-equal proportions from the VA and Part D, PUM exposure was least among VA-only users, and PUM exposure plateaued in veterans receiving prescriptions. Moreover, it was feasible that the safety risks observed in this study of veterans may extend to all subjects who receive prescriptions across disconnected health care providers or systems. To mitigate these possible risks, for all subjects seeking care across multiple healthcare systems, policies intended to extend access to non-VA providers must make sure that patient information is shared and integrated into routine practice.