Margot Egger

Increased soluble ST2 predicts long-term mortality in patients with stable coronary artery disease: results from the Ludwigshafen risk and cardiovascular health study.

BACKGROUND Soluble suppression of tumorigenicity 2 (sST2) has emerged as a strong prognostic biomarker in patients with heart failure and myocardial infarction. The aim of this study was to evaluate the long-term prognostic value of sST2 in patients with stable coronary artery disease (CAD). METHODS sST2 plasma concentrations were measured in 1345 patients with stable CAD referred for coronary angiography at a single tertiary care center. The primary endpoint was all-cause mortality. RESULTS During a median follow-up time of 9.8 years, 477 (36%) patients died. The median sST2 plasma concentration at baseline was significantly higher among decedents than survivors (21.4 vs 18.5 ng/mL; P < 0.001). In multivariate Cox proportional hazards regression analysis, sST2 was an independent predictor of all-cause mortality (risk ratio 1.16 per 1-SD increase in log-transformed values; 95% CI 1.05-1.29; P = 0.004). In the same multivariate analysis, amino-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (hs-cTnT) were also independent predictors, whereas galectin-3 was not. Patients with sST2 in the highest quartile (>24.6 ng/mL) displayed a 2-fold increased risk of death in univariate analysis, which was attenuated but remained significant in a fully adjusted model (risk ratio 1.39; 95% CI 1.10-1.76; P = 0.006). Further analysis showed that the prognostic impact of sST2 was additive to NT-proBNP and hs-cTnT. Using a multibiomarker approach combining these 3 complementary makers, we demonstrated that patients with all 3 biomarkers in the highest quartiles had the poorest outcome. CONCLUSIONS In this cohort of patients with stable CAD, increased sST2 was an independent predictor of long-term all-cause mortality and provided complementary prognostic information to hs-cTnT and NT-proBNP.

Increased Soluble Suppression of Tumorigenicity 2 (sST2) Predicts Long-Term Mortality in Patients with Stable Coronary Artery Disease: Results from the Ludwigshafen Risk and Cardiovascular Health (LURIC) Study

BACKGROUND Soluble suppression of tumorigenicity 2 (sST2) has emerged as a strong prognostic biomarker in patients with heart failure and myocardial infarction. The aim of this study was to evaluate the long-term prognostic value of sST2 in patients with stable coronary artery disease (CAD). METHODS sST2 plasma concentrations were measured in 1345 patients with stable CAD referred for coronary angiography at a single tertiary care center. The primary endpoint was all-cause mortality. RESULTS During a median follow-up time of 9.8 years, 477 (36%) patients died. The median sST2 plasma concentration at baseline was significantly higher among decedents than survivors (21.4 vs 18.5 ng/mL; P < 0.001). In multivariate Cox proportional hazards regression analysis, sST2 was an independent predictor of all-cause mortality (risk ratio 1.16 per 1-SD increase in log-transformed values; 95% CI 1.05-1.29; P = 0.004). In the same multivariate analysis, amino-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (hs-cTnT) were also independent predictors, whereas galectin-3 was not. Patients with sST2 in the highest quartile (>24.6 ng/mL) displayed a 2-fold increased risk of death in univariate analysis, which was attenuated but remained significant in a fully adjusted model (risk ratio 1.39; 95% CI 1.10-1.76; P = 0.006). Further analysis showed that the prognostic impact of sST2 was additive to NT-proBNP and hs-cTnT. Using a multibiomarker approach combining these 3 complementary makers, we demonstrated that patients with all 3 biomarkers in the highest quartiles had the poorest outcome. CONCLUSIONS In this cohort of patients with stable CAD, increased sST2 was an independent predictor of long-term all-cause mortality and provided complementary prognostic information to hs-cTnT and NT-proBNP.

Association of the biomarkers soluble ST2, galectin-3 and growth-differentiation factor-15 with heart failure and other non-cardiac diseases.

BACKGROUND The biomarkers soluble ST2 (sST2), galectin-3, and growth-differentiation factor-15 (GDF-15) provide prognostic information in patients with heart failure (HF). The aim of this study was to evaluate to which extent plasma concentrations of these biomarkers are increased in HF compared with diverse non-cardiac conditions such as infectious disease or chronic kidney disease. METHODS We recruited 15 patients in each of the following clinical categories: HF without co-morbidity, pneumonia without co-morbidity, chronic obstructive pulmonary disease (COPD) without co-morbidity, HF and a co-morbidity of pneumonia, renal disease without co-morbidity, and sepsis. We used 22 healthy individuals as control group. In each of the 112 study participants, we measured plasma concentrations of sST2 (Presage assay), galectin-3 (Abbott assay) and GDF-15 (Roche assay). RESULTS Compared to controls, the median sST2 concentration was ~2.5-fold increased in HF, ~3.5-fold in pneumonia, ~5.0-fold in COPD, ~5.8-fold in HF+pneumonia, and ~70-fold in sepsis (p<0.001 for all). sST2 was not significantly increased in renal disease. Compared to controls, the median galectin-3 concentration was ~1.5-fold increased in HF, ~1.4-fold in pneumonia, ~2.4-fold in HF+pneumonia, ~2.5-fold in renal disease, and ~2.7-fold in sepsis (p<0.001 for all). Galectin-3 was not significantly increased in COPD. Compared to controls, the median GDF-15 concentration was ~4.4-fold increased in HF, ~5.4-fold in pneumonia, ~2.1-fold in COPD, ~8.3-fold in HF+pneumonia, ~5.1-fold in renal disease, and ~27-fold in sepsis (p<0.001). In the 112 study participants, correlation analyses revealed a relatively strong association between galectin-3 and GDF-15 (correlation coefficient, 0.739; p<0.001). CONCLUSION Because increased plasma concentrations of sST2, galectin-3, and GDF-15 are not specific for a distinct disease group, the three biomarkers are not useful for diagnostic purposes. The results of our study are novel with respect to sST2, galectin-3 and GDF-15 as markers of inflammatory diseases and should encourage further studies.

Analytical characterization and clinical evaluation of an enzyme-linked immunosorbent assay for measurement of afamin in human plasma☆

Background Comparative proteomics has recently identified afamin, the newest member of the albumin gene family, as a potential biomarker for ovarian cancer. The aim of this study was the analytical and clinical evaluation of a sandwich enzyme-linked immunosorbent assay for the determination of afamin in human plasma. Methods We evaluated precision, linearity, and detection limit of the assay, analyte stability and biological variability, determined reference values and quantified afamin concentrations in various diseases. Results Within-run and total coefficients of variation were < 10%. The method was linear across the tested measurement range. Detection limit was 7 mg/L for the assay. The analyte was stable for 24 h at room temperature, for 48 h at 4 °C, and for at least one year at − 20 °C and − 80 °C. The reference change value for healthy individuals was 24%. Age- and sex-independent reference values in healthy blood donors were 45–99 mg/L (median 68 mg/L). In the clinical assay evaluation afamin plasma concentrations were modestly decreased in patients with heart failure. Patients with pneumonia or sepsis exhibited markedly decreased afamin plasma concentrations. However, patients with chronic renal disease or chronic obstructive pulmonary disease showed no difference in afamin plasma concentrations as compared to healthy individuals. Correlation analyses revealed an inverse association between afamin and inflammatory biomarkers. Conclusions The afamin assay meets quality specifications for laboratory medicine. The results of the clinical assay evaluation revealed novel insights with respect to afamin as a potential negative acute phase protein and should encourage further studies.

Prognostic value of soluble ST2 in an unselected cohort of patients admitted to an intensive care unit — The Linz Intensive Care Unit (LICU) study

BACKGROUND Soluble ST2 (sST2) has emerged as a prognostic biomarker in patients with heart disease. We tested the hypothesis that sST2 is an independent predictor of mortality in patients admitted to an intensive care unit (ICU). METHODS We performed measurements of sST2 plasma concentrations in 530 consecutive patients admitted to a medical ICU of a tertiary care hospital during a study period of one year. The patients recruited during the first six months were used for the derivation cohort (n=274) and the patients recruited during the second six months were used for the validation cohort (n=256). The endpoint was defined as 90-day all-cause mortality. RESULTS In the derivation cohort, sST2 was higher among decedents (n=56; median, 146 U/mL) than survivors (n=218; median 42 U/mL, p<0.001). In multivariate Cox proportional-hazard regression analysis (offering age, sex, BMI, APACHE II score, SAPS II, CRP, IL-6, PCT, creatinine, total cholesterol, albumin, hs-cTnT, BNP and sST2 as independent variables), sST2 was a significant predictor of mortality (risk ratio 1.48, 95% CI 1.15-1.90; p=0.002 per 1 SD increase in log transformed values). In this statistical model, only sST2 and SAPS II contributed independently to mortality prediction. We further observed an additive effect of an sST2 plasma concentration of >84 U/mL and an increased SAPS II for mortality prediction. The findings from the derivation cohort were confirmed in the independent validation cohort. In those patients with a length of stay of >48 h at the ICU (n=225), sST2 obtained two days after baseline measurement had a better capability than baseline sST2 to predict mortality. CONCLUSIONS In an unselected cohort of patients admitted to the ICU, sST2 was an independent predictor of 90-day all-cause mortality and added prognostic information to the SAPS II.

Long-term stability of soluble ST2 in frozen plasma samples

OBJECTIVE The aim of this study was to investigate the long-term in vitro stability of soluble ST2 (sST2). DESIGN AND METHODS EDTA plasma samples were drawn from 15 individuals with various diseases. The Presage ST2 assay was used for measurement of sST2 concentrations directly after blood collection and after storing plasma samples for 18 months at -20 degrees C and -80 degrees C. The default criterion for analyte stability was set at 95%. RESULTS sST2 concentrations in the 15 individuals ranged from 12 U/mL to 140 U/mL. Directly after blood collection, the mean (+/-SD) sST2 concentration was 51+/-37 U/mL, and absolute analyte recoveries were 50+/-35 U/mL and 51+/-34 U/mL after storage of samples for 18 months at -20 degrees C and -80 degrees C, respectively. Relative analyte recoveries after 18 months of storage at -20 degrees C and -80 degrees C were 99+/-5% and 101+/-7%. CONCLUSION sST2 is stable for at least 1.5 years in plasma samples stored at -20 degrees C and -80 degrees C.

Soluble ST2 is not independently associated with androgen and estrogen status in healthy males and females

Abstract Background: Soluble ST2 (sST2) plasma concentrations are significantly higher in healthy men than in healthy women. The reason for the sex-specific difference of sST2 plasma concentrations is not established. The aim of this study was to evaluate the association of sST2 with sex-hormones in healthy males and females separately. Methods: We recruited 528 consecutive blood donors and measured plasma concentrations of sST2 and several sex-hormones (i.e., total testosterone, estradiol, sex hormone-binding globulin, follicle-stimulating hormone, and luteinizing hormone). Of the 528 blood donors, 338 were male and 190 were female. For data analysis, we further divided the group of females into the subgroups of pre- and postmenopausal women using the age of 50 years as a proxy for menopause. Results: In non-parametric Spearmans correlation analyses, we found a weak association between sST2 and total testosterone (rs+0.126, p=0.021) and also between sST2 and estradiol (rs+0.117, p=0.032) in males. In females <50 years of age (n=158) and ≥50 years of age (n=32), respectively, we did not detect any significant association between sST2 and sex-hormones. As a result of multiple linear regression analyses (calculated with log sST2 as dependent variable and log of age and all sex-hormones as explanatory variables), there was no independent association between sST2 and any of the sex-hormones neither in males nor in females. Conclusions: In the present study cohort we did not find an independent association of sST2 with sex-hormones in healthy males and females. Therefore, the reason for the sex-specific difference of sST2 plasma concentrations still remains unclear.

Analytical and clinical evaluation of a rapid quantitative lateral flow immunoassay for measurement of soluble ST2 in human plasma.

BACKGROUND Soluble ST2 (sST2) is gaining growing interest as a biomarker in heart failure. So far, the ELISA-format is widely used for commercially available ST2 assays, which hampers their use in clinical routine. Recently, a rapid quantitative lateral flow immunoassay for the measurement of sST2 in human plasma has been developed. METHODS We evaluated precision and linearity of the ASPECT-PLUS ST2 test, and performed an analytical and clinical assay comparison with the MBL and the PRESAGE ST2 ELISAs. We measured sST2 with these three assays in a clinical cohort of 251 consecutive patients with acute dyspnea as the chief compliant (i.e., 137 patients with dyspnea attributable to heart failure and 114 patients with dyspnea attributable to other reasons). RESULTS Within-run and total coefficients of variation of the ASPECT-PLUS ST2 test were < 17% and the assay was linear across its measurement range. We found a constant and proportional bias between the MBL ST2 assay, the PRESAGE ST2 assay and the ASPECT-PLUS ST2 test, respectively. However, at the proposed cut-off of 35 ng/mL, sST2 results obtained with the PRESAGE ST2 assay and the ASPECT-PLUS ST2 test were similar. Testing clinically, the three assays deemed equally useful for the diagnosis of heart failure (AUC, 0.670 for the MBL ST2 assay vs. 0.626 for the PRESAGE ST2 assay vs. 0.630 for the ASPECT-PLUS ST2 test) and for the prediction of 1-year mortality in dyspnoeic patients (AUC, 0.743 for the MBL assay vs. 0.742 for the PRESAGE ST2 assay vs. 0.752 for the ASPECT-PLUS ST2 test). CONCLUSION The ASPECT-PLUS test meets the analytical requirements for point-of-care testing. Test results of the ASPECT-PLUS ST2 and the PRESAGE ST2 methods were comparable at the proposed cut-off, and the diagnostic/prognostic capabilities of the three methods were similar.

Interleukin 6, galectin 3, growth differentiation factor 15, and soluble ST2 for mortality prediction in critically ill patients

PURPOSE The aim of this study was to compare the prognostic value of interleukin 6 (IL-6), galectin 3, growth differentiation factor 15 (GDF-15), and soluble ST2 (sST2) in an unselected cohort of critically ill patients. METHODS During a study period of 1 year, we recruited 530 consecutive patients admitted to a medical intensive care unit of a tertiary care hospital. We examined a combination of inflammatory, renal, and cardiac biomarkers for the prediction of 90-day all-cause mortality. RESULTS During follow-up, 118 patients died (22%). In univariate analyses, increased IL-6, galectin 3, GDF-15, and sST2 plasma concentrations at baseline were strong prognostic markers. However, in the multivariate models, only IL-6 and sST2 remained independent biomarkers adding additional prognostic information to the routinely used Simplified Acute Physiology Score (SAPS) II. Using a simple multimarker approach, patients with increased SAPS II, IL-6, and sST2 (ie, SAPS II >35, IL-6 >32.3pg/mL, and sST2 >103ng/mL) had the poorest outcome. CONCLUSIONS In this heterogeneous group of critically ill patients, only SAPS II, IL-6, and sST2 remained independent and additive prognostic markers for 90-day all-cause mortality. A combination of the SAPS II with the 2 complementary biomarkers might provide a valuable tool for risk stratification of critically ill patients.

One-year in vitro stability of cardiac troponins and galectin-3 in different sample types

BACKGROUND We assessed the long-term in vitro stability of cardiac troponins and galectin-3 under different storage conditions. METHODS We used high-sensitivity cardiac troponin I (hs-cTnI) and galectin-3 assays from Abbott and a high-sensitivity cardiac troponin T (hs-cTnT) assay from Roche. The analyte concentrations of 30 patients were measured in heparin-treated plasma, EDTA-treated plasma and serum samples after the following storage conditions: 1) samples used immediately after blood collection for baseline measurements; 2) samples stored for 0.5year at -80°C after one freeze-thaw cycle; 3) samples stored for 1.0year at -80°C after two freeze-thaw cycles; and 4) samples stored for 1.0year at -80°C after one freeze-thaw cycle. According to the concept of acceptable change limits (ACL) the analytes were considered stable as long as the median concentration at a particular time point was >80%. RESULTS Baseline hs-cTnI, hs-cTnT and galectin-3 concentrations ranged from 2.3 to 5436ng/L, from 5.3 to 850ng/L, and from 8.3 to 79.3ng/mL, respectively. After applying the default criterion for analyte stability, the three analytes were stable for at least 1.0year even after two freeze-thaw cycles for each sample type. We observed the following variation in analyte concentrations after storage relative to the baseline values: the interquartile range (IQR) of cardiac troponin results extended from approx. 80 to 115%, and the IQR of galectin-3 results extended from approx. 90 to 110%. CONCLUSION hs-cTnI, hs-cTnT and galectin-3 were stable under the reported storage conditions irrespective of the sample type used. However, we observed a considerable variation in analyte concentrations after sample storage, which might affect the diagnostic/prognostic value of these analytes in individual patients using frozen blood samples.