NT-proBNP levels might predict outcomes in severe sepsis, but renal function cannot be ignored.

We read with great interest the article by Carlo Custodero et al. recently published in Critical Care [1]. The authors concluded that NT-proBNP levels during the acute phase of sepsis may be a useful indicator of higher risk of long-term impairments in physical function and muscle strength in sepsis survivors. However, the article overlooks the association of NT-proBNP and renal function in septic patients. Studies have shown that acute kidney injury is a common complication of sepsis and is significantly associated with mortality [2, 3], whereas the studies by Gergei et al. [4] and Roberts et al. [5] indicated that NT-proBNP plasma level has shown an exponential increase with declining glomerular filtration rate. Thus, it did not seem persuasive that NT-proBNP could completely predict outcomes without adjusting for the covariate of renal function. We suggest the relationship of the NT-proBNP levels during the acute phase of sepsis and physical function and muscle strength outcomes in sepsis survivors be stratified based on the renal function.