Abstract 284: Social Determinants of Health and 90 Day Mortality after Hospitalization for Heart Failure in the REasons for Geographic and Racial differences in Stroke (REGARDS) Study
Authors: Sterling Madeline R , Ringel Joanna B , Pinheiro Laura C , Safford Monika M , Levitan Emily B , Phillips Erica , Goyal Parag 
Published: April 2019

Background:
Mortality after heart failure (HF) hospitalizations is high, with 15-20% of patients dying within 90 days. Prior studies have found that individual social determinants of health (SDOH) are associated with mortality after discharge, heightening interest in SDOH as risk factors for 90-day mortality. However, little is known about how the burden of SDOH within individuals affects 90-day mortality. We examined associations between multiple within-person SDOH and 90-day mortality among adults hospitalized for HF.

Methods:
We used data from the REGARDS study, a large prospective cohort of 30,239 US black and white adults recruited in 2003-7, with ongoing follow-up. We studied participants 65 years of age and older who were discharged alive after an expert-adjudicated HF hospitalization, with continuous Medicare Part A for 6 months before and 90 days after hospitalization. The primary outcome was 90-day mortality. Informed by the HealthyPeople 2020 framework for SDOH, we examined 8 SDOH: 1) black race; 2) low educational attainment; 3) low annual household income; 4) social isolation; and living in a: 5) zip code with high poverty; 6) Health Professional Shortage Area (HPSA); 7) rural area; and 8) state with poor public health infrastructure. Using cox proportional hazards models, we first examined the age-adjusted association between each SDOH and 90-day mortality; those associated with p<0.20 were retained to create groups of participants with 0, 1, and 2+ SDOH. We then determined hazard ratios (HR) for SDOH groups and 90-day mortality, adjusting for demographics, medical conditions, cognition, functional status, and hospitalization characteristics.

Results:
Over 10 years, a total of 690 individuals were hospitalized for HF at 440 unique hospitals across the US. They had a mean age of 76 years and 44% were female. We observed 79 deaths within 90 days of hospitalization. Of 8 candidate SDOH, black race (HR: 1.56 [95% CI: 0.99-2.43]), HPSA (1.56 [1.00-2.42]), social isolation (1.71 [0.99-2.97]), and living in a rural area (1.68 [.88- 3.19]) were associated with increased risk of age-adjusted 90-day mortality. Overall, 37% had no SDOH, 40% had 1, and 23% had 2+ SDOH. Compared to those with fewer SDOH, participants with 2+ vulnerabilities were younger, female, had less education and income, worse overall health, and were more often discharged to a nursing home. In a fully adjusted model, compared to those with 0 or 1 SDOH, the HR for 90-day mortality among those with 2+ SDOH was 1.24 (95% CI: 0.72 -2.14).

Discussion:
Four SDOH were individually associated with increased risk of 90-day mortality, but a greater number of SDOH within individuals was not independently associated.Larger studies that can operationalize a greater number of SDOH may shed more light on the relationship between the burden of SDOH and 90-day mortality following hospitalization for HF.