The difference between the effects of CKD on NT-proBNP and BNP levels is controversial. McCullough et al. (17) previously reported an analysis from the Breathing Not Properly Multinational Study, in which BNP levels were found to be related to renal function in patients both with and without acute CHF. In our study, NT-proBNP concentrations appeared to be more affected than BNP by renal function; however, the relationship between NT-proBNP levels and renal function was much more modest than had been previously suggested (18,21); as well, the performance of NT-proBNP was comparable with that reported for BNP: in ROC analyses, we demonstrated an area under the ROC curve for NT-proBNP of 0.88 in analyses among patients with moderate or worse renal insufficiency, and in those with the most severe renal insufficiency in the PRIDE study, the area under the ROC curve remained 0.86. Among patients with similar renal function in the Breathing Not Properly Study (17), ROC analyses for BNP demonstrated an area under the curve range of 0.81 to 0.86, depending on severity of renal function impairment. Importantly, at an optimal cut point (of 1,200 pg/ml) for those with moderate-to-severe renal insufficiency, NT-proBNP had a specificity that compared favorably with results for BNP (24). Thus, despite previous suggestions (18,21), at optimal cut points, it is inaccurate to state that decreasing specificity for acute CHF due to worsening renal insufficiency is an issue unique to NT-proBNP; irrespective of renal function, our data strongly support the value of NT-proBNP testing for dyspneic patients for diagnosis and prognosis.