Pre-operative N-terminal pro-B-type natriuretic peptide for prediction of acute kidney injury after noncardiac surgery: A retrospective cohort study.

BACKGROUND: Acute kidney injury (AKI) is associated with poor outcomes after noncardiac surgery. Whether pre-operative N-terminal pro-B-type natriuretic peptide (NT-proBNP) predicts AKI after noncardiac surgery is unclear. OBJECTIVE: To investigate the predictive role of pre-operative NT-proBNP on postoperative AKI. DESIGN: Retrospective cohort study. SETTING: Nanfang Hospital, Southern Medical University, China. PATIENTS: Adult patients who had a serum creatinine and NT-proBNP measurement within 30 pre-operative days and at least one serum creatinine measurement within 7 days after noncardiac surgery between February 2008 and May 2018 were identified. MAIN OUTCOME MEASURES: The primary outcome was postoperative AKI, defined by the kidney disease: improving global outcomes creatinine criteria. RESULTS: In all, 6.1% (444 of 7248) of patients developed AKI within 1 week after surgery. Pre-operative NT-proBNP was an independent predictor of AKI after adjustment for clinical variables (OR comparing top to bottom quintiles 2.29, 95% CI, 1.47 to 3.65, P < 0.001 for trend; OR per 1-unit increment in natural log transformed NT-proBNP 1.27, 95% CI, 1.16 to 1.39). Compared with clinical variables alone, the addition of NT-proBNP improved model fit, modestly improved the discrimination (change in area under the curve from 0.764 to 0.773, P = 0.005) and reclassification (continuous net reclassification improvement 0.210, 95% CI, 0.111 to 0.308, improved integrated discrimination 0.0044, 95% CI, 0.0016 to 0.0072) of AKI and non-AKI cases, and achieved higher net benefit in decision curve analysis. CONCLUSIONS: Pre-operative NT-proBNP concentrations provided predictive information for AKI in a cohort of patients undergoing noncardiac surgery, independent of and incremental to conventional risk factors. Prospective studies are required to confirm this finding and examine its clinical impact. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR1900024056. www.chictr.org.cn/showproj.aspx?proj=40385.