Characteristics of the study patients at intensive care unit admission.

AKI: acute kidney injury; ICU: intensive care unit; CKD: chronic kidney disease; eGFR: estimated glomerular filtration rate; CHF: cardiac heart failure; BUN: blood urea nitrogen; SOFA: Sequential Organ Failure Assessment; APACHE: Acute Physiology and Chronic Health Evaluation AKI according to serum creatinine is defined as an increase in serum creatinine level of more than 27 μmol/l or more than 50% from a reference creatinine within 48 hours with or without urine output less than 0.5 ml/kg/hour for at least 6 hours (AKIN criteria) AKI according to urine output alone was defined as urine output less than 0.5 ml/kg/hour for at least 6 hours without significant changes in serum creatinine No AKI was defined as no significant changes in serum creatinine or urine output *to convert from μmol/l to mg/dl, divide by 88.4 **to convert from mmol/l to mg/dl, multiply by 2.81 Characteristics of the study patients at intensive care unit admission.