Abstract Body: Introduction: Emerging evidence links radon to prevalent risk factors for heart failure (HF), but little is known about the radon-HF association, itself.
Hypothesis: Indoor radon is associated with incident HF.
Methods: We conducted a prospective cohort study in the Women’s Health Initiative among black, Hispanic/Latina or clinical trial participants without HF at baseline (1993-1998), but with HF follow-up through 2/17/24. We used U.S. Environmental Protection Agency (EPA) data to estimate and categorize radon concentrations at geocoded participant addresses as <2, 2–4 and ≥4 pCi/L. We ascertained incident hospitalization for acute, decompensated HF via physician-review of medical records, classification and adjudication. We estimated hazard ratios and 95% confidence intervals (HR, 95%CI) using multi-variable adjusted Cox proportional hazards models on an attained age time scale. We examined sensitivity of the fully adjusted associations and expressed them in terms of equivalent increases in systolic blood pressure and body mass index to facilitate interpretation. We used Levin’s formula and a nonparametric bootstrap to estimate population-attributable fractions (PAF) at concentrations ≥2 pCi/L.
Results: Among 43,188 women (mean age 63 years; 59% white; 15% Hispanic/Latina; 75% in the clinical trial), approximately 36%, 41% and 23% had a radon concentration <2, 2–4 and ≥4 pCi/L. Over a mean of 16.2 years, we ascertained 3,446 incident HF events among them (Figure): 50%, 33%, 16% and <1% with preserved, reduced, unknown and recovered ejection fraction (EF). The unadjusted HRs (95%CIs) were 1.07 (0.99–1.16) and 1.17 (1.08–1.28) times higher at 2–4 and ≥4 than <2 pCi/L, changing little with cumulative adjustment for covariates. Associations were robust in most sensitivity analyses, but lower for HF with preserved EF: 1.06 (0.94–1.20) and 1.10 (0.94–1.28), higher for HF with reduced EF: 1.14 (0.98–1.34) and 1.29 (1.07–1.55), and highest for HF mortality: 1.18 (0.99–1.42) and 1.37 (1.10–1.70). The HR at ≥4 pCi/L approximated that of 15 mmHg and 5 kg/m² increases in systolic blood pressure and body mass index. The PAF (95%CI) for radon ≥2 pCi/L was 7.0% (1.7%–12.1%).
Conclusions: Radon may be a modifiable environmental determinant of incident HF among postmenopausal women in the U.S.