Abstract Body (Do not enter title and authors here): Introduction
Chronic limb-threatening ischemia (CLTI) is associated with significant morbidity and mortality, and has a high risk of limb amputation. Previous studies have found gender and racial disparities with regards to mortality and disease severity, but the impact of other social factors such as housing status has yet to be investigated. Identifying potential disparities is key to developing targeted interventions to address inequities in social determinants of health.

Research Question
What impact does housing status have on inpatient outcomes of limb-threatening ischemia?

Methods
A retrospective analysis using the National Inpatient Sample database from 2016-2021 was carried out to identify patients admitted with CLTI who underwent revascularization, identified by ICD-10 codes. Patients were stratified by their housing status. A propensity-matched analysis was subsequently performed to compare demographics, comorbidities, mortality rates, types of intervention, and inpatient outcomes between patients with stable versus unstable housing.

Results
2,667,294 patients were identified who were admitted with a primary diagnosis of CLTI, and 463,435 (17%) underwent revascularization. Among these, 1,790 (0.4%) of patients were identified as unhoused. Patients who were unhoused were less likely to undergo open surgical intervention (aOR 0.40, CI 0.32-0.50, p=<0.001) or endovascular revascularization (aOR 0.51, CI 0.43-0.61, p<0.001). Unhoused patients had longer hospital stays (4 days longer, p<0.001), and more expensive inflation-adjusted hospital costs ($8,501 higher, p<0.001), compared to housed patients. Unhoused patients were more likely to leave against medical advice and be discharged to skilled nursing facilities rather than home. Unhoused patients also had higher rates of smoking and polysubstance use. Mortality rates were similar between housed and unhoused patients.

Conclusion
Housing status has a significant role on interventions offered and inpatient outcomes of CLTI patients. Additional research is required to understand disparities in interventions for unhoused CTLI patients. Understanding heightened risk factors for the development of CLTI in unhoused populations is key to addressing disease morbidity in these groups.