The Cost Effectiveness of Mobile Stroke Unit in the United States

Abstract

Research Objective: Ischemic stroke accounts for 87% of all strokes and is a leading cause of morbidity and mortality in the United States. Timely administration of thrombolysis (rtPA) and proper supportive care are essential to recovery of IS patients. Recent data show that compared to standard ambulances, use of Mobile Stroke Units (MSUs)-ambulances equipped with telemedicine, a stroke care team, and radiologic assistance-significantly shorten the time to rtPA administration, potentially increasing likelihood of recovery. However, it is unknown whether these health benefits are substantial to offset the high incremental costs of operating and deploying MSUs. This study assessed the cost-effectiveness care of ischemic stroke patients via MSUs compared to care via standard ambulances, using the U.S. health care sector's perspective. Study Design: We developed a Markov-based decision-tree model to track the annual transitions of individuals in a representative cohort of 1000 U.S. ischemic stroke patients across four health states (no disability, minor disability, major disability, and death), over a lifetime horizon and under two treatment scenarios: treatment via MSU vs treatment via standard ambulance. The model was parameterized using probabilities of stroke severity, likelihood of rtPA administration, and health state transition probabilities, as well as the total annual costs and disability-adjusted life years (DALYs) associated with each health state. All parameter values were derived from the published literature. All costs were converted to year 2018 U.S. dollars. Total discounted costs, DALYs, incremental costs, DALYs averted, and incremental cost-effectiveness ratio (ICER) of care via MSU, relative to care standard ambulance, were calculated. A probabilistic sensitivity analysis with 1000 iterations of the model was conducted to account for uncertainty in the model's parameter values. Population Studied: Population consisted of a representative cohort of 1000 ischemic stroke patients 18 years and older, living in the United States. Principal Findings: Preliminary base case results show that relative to care via standard ambulances, care via MSUs averted 651 discounted DALYs (87 406 vs 88 057 DALYs, respectively) at an additional discounted cost of 11 million (195 million vs 184 million, respectively). Assuming an average U.S. willingness-to- pay threshold of 150 000 per DALY averted, our results demonstrate that treatment of ischemic stroke via MSU is highly cost-effective compared to care via standard ambulance, resulting in 17 498 per DALY averted. The probability sensitivity analysis showed that the ICER was robust to uncertainty in parameter values, with 85% of simulated values being cost-effective at the willingness-to- pay threshold of 150 000/DALY averted. Conclusions: Results suggest that from a U.S. health care sector's perspective, care via MSU is a highly cost-effective approach for improving health outcomes after ischemic stroke compared to care via standard ambulance. Implications for Policy or Practice: Mobile Stroke Units can significantly reduce time from alarm to thrombolysis administration in ischemic stroke patients. Our preliminary findings support the adoption of care via MSU as a cost-effective approach for improving health outcomes in ischemic stroke patients.