Distribution and clinical correlates of the interleukin receptor family member soluble ST2 in the Framingham Heart Study

BACKGROUND: Soluble ST2 (sST2) is a cardiac bio-marker whose concentration rises in response to myocardial strain. Increased sST2 concentrations may predict adverse outcomes in patients with heart failure and myocardial infarction. Because sST2 was largely undetectable with first-generation assays in ambulatory individuals, there are few data regarding its distribution and correlates in community-based populations. METHODS: We measured sST2 using a highly sensitive ELISA in 3450 Framingham Heart Study participants who attended a routine examination. We used multivariable linear regression models to identify covariates associated with sST2 in the general sample. We obtained a reference sample (n = 1136) by excluding individuals with prevalent coronary disease, heart failure, atrial fibrillation, diabetes, hypertension, obesity, valvular disease, left ventricular systolic dysfunction, and pulmonary and renal dysfunction. We used empiric and quantile regression techniques to estimate the 2.5th, 50th, 97.5th, and 99th quantiles. RESULTS: In the general sample (mean age 59 years, 55% women), systolic blood pressure (P = 0.006), antihypertensive medication use (P = 0.03), and diabetes (P < 0.001) were associated with sST2 concentrations. In the reference sample (mean age 55, 59% women), male sex (P < 0.0001) and older age (P = 0.004) were predictive of higher sST2 concentrations. Quantile and empirical methods were used to define the reference intervals. Using the empirical approach, upper 99% percentile values in different age groups ranged from 46.6 to 64.4 μg/L in men and 36.7 to 53.0 μg/L in women. CONCLUSIONS: In a well-characterized, community-based cohort, values for sST2 differ between men and women, increase with age, and are associated with diabetes and hypertension.