Pre-Operative Serum Brain Natriuretic Peptide and Risk of Acute Kidney Injury after Cardiac Surgery
Background—Acute kidney injury (AKI) following cardiac surgery is associated with poor outcomes and is difficult to predict. We conducted a prospective study to evaluate whether pre-operative brain natriuretic peptide (BNP) levels predict postoperative AKI among patients undergoing cardiac surgery.
Methods and Results—The TRIBE-AKI Consortium enrolled 1,139 adults undergoing cardiac surgery at six hospitals from 2007-2009, who were selected for high AKI risk. Pre-operative BNP was categorized into quintiles. AKI was common using Acute Kidney Injury Network definitions; at least mild AKI was a ≥0.3mg/dL or 50% rise in creatinine, n=407 (36%), and severe AKI was either a doubling of creatinine or the requirement of acute renal replacement therapy, n=58 (5.1%). In analyses adjusted for pre-operative characteristics, pre-operative BNP was a strong and independent predictor of mild and severe AKI. Compared with the lowest BNP quintile the highest quintile had significantly higher risk of at least mild AKI (risk ratio [RR] 1.87; 1.40-2.49) and severe AKI (RR 3.17; 1.06-9.48). After adjustment for clinical predictors, addition of BNP improved the area under the curve to predict at least mild AKI (0.67 to 0.69, p=0.02) and severe AKI (0.73 to 0.75, p=0.11). Compared with clinical parameters alone, BNP modestly improved risk prediction of AKI cases into lower and higher risk (continuous net reclassification index at least mild AKI 0.183; 0.061, 0.314; severe AKI 0.231; 0.067, 0.506).
Conclusions—Pre-operative BNP level is associated with post-operative AKI in high-risk patients undergoing cardiac surgery. If confirmed in other types of patients and surgeries, pre-operative BNP may be a valuable component of future efforts to improve pre-operative risk stratification and discrimination among surgical candidates.
Clinical Trial Registration Information—clinicaltrials.gov; NCT00774137
- Received March 2, 2011.
- Accepted February 3, 2012.
- Copyright © 2012, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited