Biomarkers show robust mortality prediction in heart failure
MedWire News: Elevated levels of the biomarkers C-reactive protein (CRP), B-type natriuretic peptide (BNP), and troponin T are independent predictors for mortality in patients with heart failure, results of community-based study demonstrate.
Notably, the combination of CRP and BNP markedly increased the statistical discrimination of the prognostic model, Véronique Roger (Mayo Clinic, Rochester, Minnesota, USA) and colleagues report.
They comment in the journal Circulation, Heart Failure: “By more accurately identifying individuals at highest mortality risk, clinicians may be more effective at counseling patients, enabling them to make better informed decisions regarding use of medications and invasive procedures.
“In addition… risk assessment in a community population offers clear advantages over trial populations, as clinical trial participants are frequently younger with fewer comorbidities, and thus observed mortality may differ markedly from the general heart failure population.”
As outlined in a recent American Heart Association Scientific Statement, reporting that a biomarker is associated with outcome is not enough to demonstrate its value in risk prediction. A range of statistical methods including use of reclassification tables and the integrated discrimination improvement (IDI) should be employed.
Roger and colleagues therefore evaluated CRP, BNP, and troponin T in 593 patients, aged an average of 76.4 years, who presented with heart failure between 2004 and 2007 and were currently living in the community.
After 1 year of follow-up, 122 (20.6%) participants had died, the researchers report.
The median level of biomarkers were 11.8 mg/l for CRP, 350 pg/ml for BNP, and 0.01 ng/ml for troponin T. Patients with levels below this had a 1-year mortality of just 3.3%.
Meanwhile, those with levels of two or three biomarkers greater than the median had a significantly increased mortality at 30.8% and 35.5%, respectively.
Notably the combination of CRP and BNP resulted in an increase in the c statistic from 0.757 to 0.810, an IDI gain of 7.1%, and a net reclassification improvement of 22.1%.
In an accompanying editorial, Douglas Lee and Jack Tu, from the University of Toronto in Ontario, Canada say the findings are exciting, but caution that “although a biomarker may seem prognostically important in a statistical model, demonstrating that it can impact on and guide therapy is a quantum jump.”
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By Andrew Czyzewski