Preoperative serum brain natriuretic peptide and risk of acute kidney injury after cardiac surgery.
BACKGROUND
Acute kidney injury (AKI) after cardiac surgery is associated with poor outcomes and is difficult to predict. We conducted a prospective study to evaluate whether preoperative brain natriuretic peptide (BNP) levels predict postoperative AKI among patients undergoing cardiac surgery.


RESULTS
The Translational Research Investigating Biomarker Endpoints in Acute Kidney Injury (TRIBE-AKI) study enrolled 1139 adults undergoing cardiac surgery at 6 hospitals from 2007 to 2009 who were selected for high AKI risk. Preoperative BNP was categorized into quintiles. AKI was common with the use of Acute Kidney Injury Network definitions; at least mild AKI was a ≥0.3-mg/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 preoperative characteristics, preoperative 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, 1.87; 95% confidence interval, 1.40-2.49) and severe AKI (risk ratio, 3.17; 95% confidence interval, 1.06-9.48). After adjustment for clinical predictors, the addition of BNP improved the area under the curve to predict at least mild AKI (0.67-0.69; P=0.02) and severe AKI (0.73-0.75; 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: risk ratio, 0.183; 95% confidence interval, 0.061-0.314; severe AKI: risk ratio, 0.231; 95% confidence interval, 0.067-0.506).


CONCLUSIONS
Preoperative BNP level is associated with postoperative AKI in high-risk patients undergoing cardiac surgery. If confirmed in other types of patients and surgeries, preoperative BNP may be a valuable component of future efforts to improve preoperative risk stratification and discrimination among surgical candidates.
Section of Nephrology, Yale University and VAMC, 950 Campbell Ave., West Haven, CT 06516, USA.
Uptal D
UD
Patel
Amit X
AX
Garg
Harlan M
HM
Krumholz
Michael G
MG
Shlipak
Steven G
SG
Coca
Kyaw
K
Sint
Heather
H
Thiessen-Philbrook
Jay L
JL
Koyner
Madhav
M
Swaminathan
Cary S
CS
Passik
Chirag R
CR
Parikh
D058186:Acute Kidney Injury / Q000097:blood* / Q000209:etiology; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D011183:Postoperative Complications / Q000097:blood* / Q000209:etiology; D011300:Preoperative Care / Q000379:methods; D011446:Prospective Studies; D012307:Risk Factors
D015415:Biomarkers; D020097:Natriuretic Peptide, Brain