Incremental prognostic value of biomarkers beyond the GRACE (Global Registry of Acute Coronary Events) score and high-sensitivity cardiac troponin T in non-ST-elevation acute coronary syndrome.

BACKGROUND: Guidelines recommend the use of validated risk scores and a high-sensitivity cardiac troponin assay for risk assessment in non-ST-elevation acute coronary syndrome (NSTE-ACS). The incremental prognostic value of biomarkers in this context is unknown. METHODS: We calculated the Global Registry of Acute Coronary Events (GRACE) score and measured the circulating concentrations of high-sensitivity cardiac troponin T (hs-cTnT) and 8 selected cardiac biomarkers on admission in 1146 patients with NSTE-ACS. We used an hs-cTnT threshold at the 99th percentile of a reference population to define increased cardiac marker in the score. The magnitude of the increase in model performance when individual biomarkers were added to GRACE was assessed by the change (Δ) in the area under the receiver-operating characteristic curve (AUC), integrated discrimination improvement (IDI), and category-free net reclassification improvement [NRI(>0)]. RESULTS: Seventy-eight patients reached the combined end point of 6-month all-cause mortality or nonfatal myocardial infarction. The GRACE score alone had an AUC of 0.749. All biomarkers were associated with the risk of the combined end point and offered statistically significant improvement in model performance when added to GRACE (likelihood ratio test P ≤ 0.015). Growth differentiation factor 15 [ΔAUC 0.039, IDI 0.049, NRI(>0) 0.554] and N-terminal pro-B-type natriuretic peptide [ΔAUC 0.024, IDI 0.027, NRI(>0) 0.438] emerged as the 2 most promising biomarkers. Improvements in model performance upon addition of a second biomarker were small in magnitude. CONCLUSIONS: Biomarkers can add prognostic information to the GRACE score even in the current era of high-sensitivity cardiac troponin assays. The incremental information offered by individual biomarkers varies considerably, however.

Adjustment of the GRACE score by growth differentiation factor 15 enables a more accurate appreciation of risk in non-ST-elevation acute coronary syndrome.

AIMS: The aim of the study was to evaluate whether knowledge of the circulating concentration of growth differentiation factor 15 (GDF-15) adds predictive information to the Global Registry of Acute Coronary Events (GRACE) score, a validated scoring system for risk assessment in non-ST-elevation acute coronary syndrome (NSTE-ACS). We also evaluated whether GDF-15 adds predictive information to a model containing the GRACE score and N-terminal pro-B-type natriuretic peptide (NT-proBNP), a prognostic biomarker already in clinical use. METHODS AND RESULTS: The GRACE score, GDF-15, and NT-proBNP levels were determined on admission in 1122 contemporary patients with NSTE-ACS. Six-month all-cause mortality or non-fatal myocardial infarction (MI) was the primary endpoint of the study. To obtain GDF-15- and NT-proBNP-adjusted 6-month estimated probabilities of death or non-fatal MI, statistical algorithms were developed in a derivation cohort (n = 754; n = 66 reached the primary endpoint) and applied to a validation cohort (n = 368; n = 33). Adjustment of the GRACE risk estimate by GDF-15 increased the area under the receiver-operating characteristic curve (AUC) from 0.79 to 0.85 (P < 0.001) in the validation cohort. Discrimination improvement was confirmed by an integrated discrimination improvement (IDI) of 0.055 (P = 0.005). A net 31% of the patients without events were reclassified into lower risk, and a net 27% of the patients with events were reclassified into higher risk, resulting in a total continuous net reclassification improvement [NRI(>0)] of 0.58 (P = 0.002). Addition of NT-proBNP to the GRACE score led to a similar improvement in discrimination and reclassification. Addition of GDF-15 to a model containing GRACE and NT-proBNP led to a further improvement in model performance [increase in AUC from 0.84 for GRACE plus NT-proBNP to 0.86 for GRACE plus NT-proBNP plus GDF-15, P = 0.010; IDI = 0.024, P = 0.063; NRI(>0) = 0.42, P = 0.022]. CONCLUSION: We show that a single measurement of GDF-15 on admission markedly enhances the predictive value of the GRACE score and provides moderate incremental information to a model including the GRACE score and NT-proBNP. Our study is the first to provide simple algorithms that can be used by the practicing clinician to more precisely estimate risk in individual patients based on the GRACE score and a single biomarker measurement on admission. The rigorous statistical approach taken in the present study may serve as a blueprint for future studies exploring the added value of biomarkers beyond clinical risk scores.

Diagnostic and prognostic value of sex- and age-specific cutpoints for high-sensitivity Troponin T in non-ST-elevation acute coronary syndrome.

INTRODUCTION: Sex- and age-specific high-sensitivity Troponin T (hs-cTnT) cutpoints for the diagnosis and prognosis in acute coronary syndromes are not well established. We evaluated the use of such dichotomous thresholds for calculation of the GRACE score. METHODS: We analyzed a retrospective cohort study of 1146 patients with non-ST-elevation acute coronary syndrome (NSTE-ACS). Sex-dependent hs-cTnT cutpoints comprised 15.5 ng/L for men and 9.0 ng/L for women, while the sex-/age-specific cutpoints comprised 17 ng/L for 50-64-year-old men and ≥65-year-old women, 31 ng/L for ≥65-year-old men and 14 ng/L for the remainder of patients. RESULTS: For the diagnosis of NSTEMI using sex-specific hs-cTnT cutpoints, in women, the positive likelihood ratio (LR+) was 2.04 (1.68-2.47) while in men, the negative likelihood ratio (LR-) was 0.05 (0.04-0.07). Using sex-/age-specific hs-cTnT cutpoints, in ≥65-year-old women the LR- was 0.09 (0.06-0.15), in 50 to 64-year-old men the LR- was 0.08 (0.04-0.13) while in ≥65-year-old men the LR- was 0.32 (0.28-0.37). Sex-specific hs-cTnT cutpoints achieved an NRI of -0.020 (95% CI, -0.101-0.118) for women and 0.030 (95% CI, -0.013-0.079) for men, and the sex-/age-specific hs-cTnT cutpoints achieved an NRI of 0.061 (95% CI, -0.019-0.132) for women and 0.021 (95% CI, -0.062-0.108) for men, while net benefit and clinical utility were highest for women using the sex-/age-specific hs-cTnT cutpoints. CONCLUSIONS: Sex-dependent hs-cTNT cutpoints imply increasing diagnostic sensitivity for women at the cost of specificity. Considering age for hs-cTNT cutoffs slightly improves risk reclassification, although the overall gain in terms of the clinical management appears negligible.