Abstract 73: Sex Hormone Binding Globulin: A Novel Hormonal Biomarker for Ischemic Stroke Risk?
Introduction: Sex hormone binding globulin (SHBG) is a sex-steroid transporter previously linked to cardiometabolic outcomes such as diabetes (DM) and coronary heart disease and their risk factors. It remains uncertain whether SHBG also affects stroke risk, particularly in women. We investigated whether SHBG affects risk of incident ischemic stroke (IS) among women in the Women’s Health Initiative (WHI). Methods: The WHI includes randomized trials and an observational cohort of 161808 postmenopausal women enrolled at 40 sites across the U.S. from 1993 - 1998. We identified 13,192 participants free of prevalent stroke at baseline who were included in one of eleven ancillary studies with serum SHBG. Incident IS events through 2017 were identified via physician adjudication of medical records. We used Cox proportional hazards regression to assess IS risk across quartiles of SHBG levels (Q1 - Q4), first adjusted for demographics, body mass index (BMI), hypertension, alcohol use, and smoking status (Model 1). History of DM was added to remove indirect effects through DM (Model 2), followed by the addition of reproductive risk factors and physical activity (Model 3). Results: Of 13,192 participants (mean age 62.5 years, 67.4% non-Hispanic white, 18.5% black, 5.0% Asian, 7.6% Hispanic), 877 IS events were confirmed during follow-up. Compared to the highest SHBG quartile (referent), women in the lowest quartile had a higher risk of IS in all three models (Model 1: HR 1.51, 95%CI 1.23 - 1.86, Model 2: HR 1.46, 95%CI 1.18 - 1.80, Model 3: HR: 1.38, 95%CI 1.07 - 1.76, trend tests p <0.05 for all). Women in the middle quartiles (Q2, Q3) also had increased IS risk compared with those in the highest SHBG quartile (Table). Conclusions: In this prospective cohort of post-menopausal women, there was a statistically significant inverse association between SHBG levels and IS risk, which supports the notion that SHBG could be used as a risk stratification tool for predicting IS in women.