In their elegant meta-analyses, Porapakkham and colleagues1 conclude that B-type natriuretic peptide (BNP)-guided therapy reduces all-cause mortality in patients with chronic heart failure (HF) compared with usual clinical care.
It is not our purpose to inquire into the methods of statistical or data analysis. However, we would like to call attention to analytical performance of natriuretic peptide measurements. Specific literature is extensive. It is reported that intraindividual biological variation of BNP and N-terminal pro-BNP (NT-pro-BNP) can induce misinterpretation on disease progression or treatment optimization.2,3 Moreover, results from testing for imprecision showed systematically high total coefficients of variation. In our clinical laboratory, using Clinical and Laboratory Standards Institute–standardized protocol to verify method performance,4 data ranged from 0.9% to 50.8%, depending on sample storage and analyte (BNP or NT-pro-BNP). These uncomfortable numbers motivated a recent guidelines document addressing the clinical use of BNP and NT-pro-BNP testing in the context of HF.5
Andrade DMT, Vidigal PG, Eloi-Santos SM. Analytical Performance vs Clinical Use of Natriuretic Peptide Measurements. Arch Intern Med. 2010;170(14):1274. doi:10.1001/archinternmed.2010.230