Patient characteristics for patients with and without WRF, stratified by survival, are presented in Table 1. Patients who developed WRF during the first four days (n = 325; 22%) had a higher Left Ventricular Ejection Fraction (LVEF), higher systolic blood pressure, less edema, worse baseline renal function, higher NGAL levels, lower hemoglobin, and more anemia (all p < 0.05). Profiles for survivors at 180 days versus patients who died were similar, regardless of whether WRF developed; patients who died had a lower ejection fraction, lower blood pressure, worse renal function, reflected by higher Blood Urea Nitrogen (BUN), and plasma concentrations of creatinine and NGAL (all p < 0.05). Tables S1 and S2 present baseline characteristics, by tertiles, of baseline serum creatinine and plasma NGAL. Higher levels were associated with more advanced age and more co-morbidity. Plasma concentrations of NGAL, correlated with serum creatinine (Spearman’s rho 0.58 at baseline and 0.60 at day 4, p < 0.001), estimated GFR (Spearman’s rho −0.60 at baseline and −0.62 at day 4, p < 0.001) and BUN (Spearman’s rho 0.52 at baseline and 0.54 at day 4, p < 0.001), and modestly with CRP (Spearman’s rho 0.12 at day 1, 0.13 at day 4, p < 0.001).