Patients in the high IL-6 group had higher in-hospital 90-day mortality (low vs. middle vs. high, P = 0.0050), lower urine output (low vs. middle vs. high, P < 0.0001), and an increased probability of persistent of anuria for ≥12 h (low vs. middle vs. high, P < 0.0001) within 72 h after ICU admission.