Supplementary Material for: Variation in ischemic stroke payments in the USA: a Medicare beneficiary study

Introduction: The growing cost of stroke care has created the need for outcome-oriented and cost-saving payment models. Identifying imbalances in the current reimbursement model is an essential step towards designing impactful value-based reimbursement strategies. This study describes the variation in reimbursement fees for ischemic stroke management across the United States. Methods: This Medicare Fee-For-Service claims study examines USA beneficiaries who suffered an ischemic stroke from 2021Q1 to 2022Q2 identified using the Medicare Severity Diagnosis-Related Groups (MS-DRGs). Demographic national and regional US data were extracted from the Census Bureau. The MS-DRG codes were grouped into four categories according to treatment modality and clinical complexity. Our primary outcome of interest was payments made across individual US states and US geographic regions, assessed by computing the mean incremental payment in cases of comparable complexity. Differences between states for each MS-DRG were statistically evaluated using a linear regression model of the logarithmic transformed payments. Results: 227,273 ischemic stroke cases were included in our analysis. Significant variations were observed among all DRG-groups defined by medical complexity, treatment modality, and states (p<0.001). Differences in mean payment per case with the same MS-DRG vary by as high as 500% among individual states. Although higher payment rates were observed in MS-DRG codes with Major Comorbidities or Complexity, the variation was more expressive for codes without MCC. It was not possible to identify a standard mean incremental fee at a state level. At a regional level, the Northeast registered the highest fees, followed by the West, Midwest, and South, which correlates with poverty rates and median household income in the regions. Discussion/Conclusions: The payment variability observed across USA states suggests that the current reimbursement system needs to be aligned with stroke treatment costs. Future studies may go one step further to evaluate accurate stroke management costs to guide policymakers in introducing health policies that promote better care for stroke patients