Social Vulnerability Index and All-Cause Mortality After Acute Ischemic Stroke, Medicare Cohort 2020-2023.

Background: Inequities in stroke outcomes have existed for decades, and the COVID-19 pandemic amplified these inequities. Objectives: This study examined the association between social vulnerability and all-cause mortality among Medicare beneficiaries hospitalized with acute ischemic stroke (AIS) during COVID-19 pandemic periods. Methods: We analyzed data on Medicare fee-for-service beneficiaries aged ≥65 years hospitalized with AIS between April 1, 2020, and December 31, 2021 (followed until December 31, 2023) merged with county-level data from the 2020 Centers for Disease Control and Prevention/Agency for Toxic Substances and Disease Registry's Social Vulnerability Index (SVI). We used a Cox proportional hazard model to examine the association between SVI quartile and all-cause mortality. Results: Among 176,123 Medicare fee-for-service beneficiaries with AIS, 29.9% resided in the most vulnerable counties (SVI quartile 4), while 14.9% resided in counties with least social vulnerability (SVI quartile 1). AIS Medicare beneficiaries living in the most vulnerable counties had the highest proportions of adults aged 65 to 74 years, non-Hispanic Black or Hispanic, severe stroke at admission, a history of COVID-19, and more prevalent comorbidities. Compared to those living in least vulnerable counties, AIS Medicare beneficiaries living in most vulnerable counties had significantly higher all-cause mortality (adjusted HR: 1.11, 95% CI: 1.08-1.14). The pattern of association was largely consistent in subgroup analyses by age group, sex, and race and ethnicity. Conclusions: Higher social vulnerability levels were associated with increased all-cause mortality among AIS Medicare beneficiaries. To improve outcomes and address disparities, it may be important to focus efforts toward addressing social vulnerability.