Abstract 18023: What is the Relationship Between Summer Ambient Temperatures & Heart Failure Hospitalizations Among Low-Income Older Adults in the US?

Abstract

Background: A trend of warmer nights and higher daily minimum temperatures (T min ) during summer is a leading indicator of climate change. The impact of increased T min on hospitalizations in low-income older adults with heart failure (HF) remains unknown. Hypothesis: Higher T min increases the risk of HF hospitalization among older adults and low-income patients will be more impacted. Methods: We conducted a time-stratified case-crossover study among older adults (age ≥ 66 years) hospitalized for HF during summer months (May-Sept) between 2008-2019 using 20% Medicare data. We employed bidirectional sampling to select controls. Data on daily T min from the Parameter-elevation Relationships on Independent Slopes Model were linked using patient zip code. The non-linear effect of T min was estimated using conditional logistic regression with a restricted cubic spline in all patients and by Medicaid eligibility. Results: Among 460,072 patients hospitalized for HF (mean age 78 years, 62% female, 86% white), the risk of HF hospitalization increased nearly linearly with higher T min (OR: 74 °F = 1.09 [1.09 - 1.10], 84 °F = 1.18 [1.16 - 1.20]) relative to the median summer T min (64 °F) (Figure 1). Patients with Medicaid dual eligibility experienced greater risk of HF hospitalization than their counterparts (Figure 2). Conclusions: Among older US adults, summer days with higher T min were associated with increased risk of HF hospitalization. Low-income patients were at greater risk, possibly secondary to behavioral differences. This effect may be mediated through physiological stress from warmer nights; increased ambient temperatures are associated with inflammation and myocyte damage.