Abstract Body:
Introduction
Prior studies have demonstrated social determinants of health (SDH) are associated with reduced rates of intravenous thrombolysis (IVT) for acute ischemic stroke (AIS), including in disadvantaged populations. Mechanisms of disparity may include financial/resource limitations and systemic bias. Neighborhood measures of socioeconomic status are predictors of interest in stroke research, as they may influence emergency response, transportation, and health seeking behaviors. We sought to identify SDH factors influencing time to presentation for AIS.

Methods
This is a retrospective cohort study of 432 patients ages ≥18 presenting to Tufts comprehensive stroke center with AIS and last known well (LKW) <24hrs from arrival, from 1/1/20-12/31/22. IVT was offered in the standard 0-4.5hr window and 4.5-24hrs through Tufts Late Presenter Thrombolysis protocol. Data were collected from the EHR including demographics, stroke severity, IVT, insurance, and zip codes to obtain Gini coefficient (national inequality) and Area Deprivation Index (ADI, state deciles, dichotomized as low, 1-5, and high, 6-10). Multivariable logistic regression assessed predictors of time to presentation among all patients who presented within 24hrs of LKW. A sensitivity analysis assessed predictors among a subgroup of patients who received IVT. All analyses were performed using RStudio 1.2.1335.

Results
In an unadjusted analysis, high ADI was associated with increased odds of presenting late [OR 1.62, CI 1.06-2.56]. In an adjusted analysis including demographics and stroke severity, high ADI was similarly associated with increased odds of presenting late [OR 1.65, CI 1.05-2.61]. A second model including Gini demonstrated a similar association for ADI and late presentation [OR 1.67, CI 1.07-2.66]. In an adjusted sensitivity analysis of patients receiving IVT, high ADI was strongly associated with presentation in the later time window [OR 2.67, CI 1.03-7.22].

Conclusions
Among patients presenting within 24hrs with AIS, individuals living in neighborhoods with greater socioeconomic disadvantage are more likely to present outside the standard time window for thrombolysis. High ADI being associated with late presentation indicates socioeconomic factors prohibit patients in these areas from accessing definitive emergency healthcare services in a timely manner after AIS. Protocols to treat patients outside the standard time window may help mitigate disparities in thrombolysis treatment rates.