Predicting Acute Kidney Injury Following Non-Emergent Cardiac Surgery: A
Preoperative Scorecard
Abstract
Objective: To determine the predictors of postoperative AKI following
non-emergent cardiac surgery among patients with variable preoperative
eGFR levels. Methods: Retrospective study of patients who underwent
elective or in-hospital cardiac surgical procedures performed between
January 2006 and November 2015. The procedures included isolated CABG,
isolated AVR or combined CABG and AVR. The primary outcome AKI (any
stage) following non-emergent cardiac surgery utilizing the 2012 KDIGO
criteria. Patients were categorized based the following renal outcomes:
mild AKI, severe AKI (KDIGO stage 2 or 3) and post-operative dialysis..
Results: A total of 6713 patients were included in our study. The mean
age was 66.8 years (SD ± 10.3), with 76.2% being males. A total of 4487
patients had normal or mildly decreased eGFR (G1 or G2) preoperatively
(66.8%), while 1960 patients were in the G3 category (29.1%). Only 266
patients (3.9%) had G4 or worse renal function. A total of 1489
(28.5%) patients experienced post-operative AKI. The need for
postoperative dialysis occurred in 4.2% of the AKI subgroup.
In-hospital mortality was higher among the AKI subgroup (7.3% vs 0.5%,
p<0.0001). In an adjusted model, a lower pre-operative eGFR
category was the strongest predictor of AKI. A practical scorecard for
the preoperative estimation of severe AKI for non-emergent cardiac
procedures incorporating these parameters was developed. Conclusions:
Preoperative eGFR is the strongest predictor of post-operative AKI in
individuals undergoing non-emergent cardiac surgery. A practical
scorecard incorporating preoperative predictors of AKI may allow
informed decision making and to predict AKI following non-emergent
cardiac surgery