Researchers analyze eGFR-specific thresholds for cardiac biomarkers in patients with CKD
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Using data from two major studies, researchers identified higher distributions of N-terminal pro brain natriuretic peptide and high sensitivity cardiac troponin T in lower categories of eGFR among patients with chronic kidney disease.
“Upper reference limits for N-terminal pro brain natriuretic peptide (NT-proBNP) and high sensitivity cardiac troponin T (hsTnT) are applied to determine probability of disease, which are often derived from the manufacturer’s-reported 99th percentile upper reference limit or from data reflecting the negative predictive value from select populations. The current upper reference limit for hsTnT is 14 ng/L and for NT-proBNP is 125 pg/mL,” Nisha Bansal, MD, from the division of nephrology at the University of Washington, and colleagues wrote. “Reduced eGFR contributes, in part, to elevations in hsTnT and NT-proBNP due to reduced kidney excretion as well as structural heart disease commonly seen in CKD.”
Researchers observed that among patients within the Chronic Renal Insufficiency Cohort (CRIC), 40% to 88% of participants had concentrations of NT-proBNP and hsTnT above conventional upper reference limits, with greater proportions above the upper reference limit in those in lower eGFR strata.
“We proposed eGFR-specific thresholds for hsTnT and NT-proBNP using the 95th and 99th percentiles in CRIC,” Bansal and colleagues wrote.
After excluding patients with missing NT-proBNP and hsTnT, an eGFR greater than 60 mL/min/1.73m2, prevalent cardiovascular disease or heart failure at enrollment, researchers evaluated 1,768 patients (mean age was 73 years; mean eGFR was 46 mL/min/1.732 m) from the Systolic Blood Pressure Intervention Trial (SPRINT) with CKD.
Researchers accessed samples of NT-proBNP and hsTnT that were taken at enrollment and identified the amount of SPRINT participants above 95% and 99% thresholds established in CRIC. The overall number was determined in addition to across strata by eGFR category.
Researchers examined the proportions across strata of sex, race and age in a secondary analysis.
Analyses revealed the amount of NT-proBNP and hsTnT were higher in lower categories of eGFR. Researchers observed similar 95% and 99% thresholds for NT-proBNP among CRIC and SPRINT. In regard to hsTnT, the CRIC 95% (58 ng/L) and 99% (126 ng/L) thresholds identified 1% and 0.1% of SPRINT participants above the upper reference limits, respectively. Researchers suggested that the proposed thresholds might not have replicated due to the differences in the study populations.
“In conclusion, 95th% and 99th% thresholds for NT-proBNP developed in CRIC across eGFR strata were similar in SPRINT participants with CKD. However, the CRIC hsTnT thresholds did not replicate, and larger studies are needed to identify eGFR-specific hsTnT thresholds,” Bansal and colleagues wrote. “Further work is needed to validate eGFR-specific thresholds for cardiac biomarkers in patients presenting with acute symptoms to evaluate their accuracy for the diagnosis acute heart failure and myocardial infarction in patients with a broad range of eGFR.”
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