Abstract Body (Do not enter title and authors here): Introduction: Acute Heart Failure (AHF) is the leading cause of hospitalization in adults over 65. Prolonged hospital stays increase morbidity and costs. While clinical severity is a known contributor to length of stay (LOS), the influence of social factors is less understood. This study aims to identify clinical and social determinants associated with hospital LOS in AHF patients presenting to the emergency department (ED), with a focus on the predictive value of the Emergency Heart Failure Mortality Risk Grade (EHMRG) score.

Research Questions: How does the EHMRG score correlate with extended LOS in AHF patients admitted through the ED? What social determinants of health are most strongly associated with extended hospital LOS in AHF patients?

Methods: The study presents a pilot analysis of a larger multicenter retrospective study of 15,000 AHF patients admitted via nine EDs in 2019. A stratified random sample of 2,400 admissions underwent manual chart review. Data from electronic health records included demographics, medical history, vital signs, labs, and social risk factors. Prior-year ED notes were reviewed for visit frequency, and EHMRG scores were calculated. Patients were grouped by LOS: <5 days, 5–10 days, or >10 days. Primary outcomes included risk scores, labs, healthcare utilization, and discharge plans. Descriptive statistics, chi-square, and ANOVA were used (p<0.05).

Results: A total of 592 AHF patients were analyzed (mean age 77.3; 51.9% male); 309 had LOS <5 days and 109 had LOS >10 days. The >10 day group had significantly higher EHMRG scores (p<0.001) and elevated creatinine levels (p=0.0052) compared to the <5 days group. Social determinants were also strongly associated with extended LOS. Patients with financial concerns at discharge had longer LOS (p=0.01), and patients discharged to short-term skilled nursing facilities were significantly more likely to have LOS >10 days compared to <5 days (p<0.00001).

Conclusion: Higher EHMRG scores and elevated creatinine levels were significant clinical predictors of extended LOS. Social factors such as financial concerns and discharge to skilled nursing facilities were also independently associated with prolonged hospitalization. These findings underscore the value of integrating social determinants into risk stratification and discharge planning. Future efforts should develop integrated clinical-social predictive models to improve outcomes and reduce avoidable hospital utilization.