title: Urinary interleukin-18 does not predict acute kidney injury after adult cardiac surgery: a prospective observational cohort study.
abstract: BACKGROUND
  Urinary interleukin-18 (IL-18) measured during the immediate postoperative period could be a promising predictor of acute kidney injury following adult cardiac surgery.
  
  
  METHODS
  In a single-centre prospective observational cohort study, we enrolled 100 adult cardiac surgical patients undergoing cardiopulmonary bypass at a tertiary hospital. We measured the urinary concentration of IL-18 and creatinine preoperatively, on arrival in the intensive care unit, and 24 hours postoperatively. We assessed urinary IL-18 concentration and urinary IL-18/urinary creatinine ratio in relation to the postoperative development of acute kidney injury defined as an increase in serum creatinine of greater than 50% from preoperative to postoperative peak value within 48 hours after surgery.
  
  
  RESULTS
  Twenty patients developed acute kidney injury. On arrival in the intensive care unit and at 24 hours postoperatively, urinary IL-18 (median [interquartile range]) was not different in patients who subsequently developed acute kidney injury compared with those who did not: on arrival in the intensive care unit (168 [717] versus 104 [256] pg/mL; P = 0.70) and at 24 hours (195 [483] versus 165 [246] pg/mL; P = 0.47). On arrival in the intensive care unit (area under the curve for the receiver operating characteristic curve [AUC-ROCC] 0.53, 95% confidence interval [CI] 0.38 to 0.68; P = 0.70) and at 24 hours postoperatively (AUC-ROCC 0.55, 95% CI 0.40 to 0.71; P = 0.48), urinary IL-18 was not better than chance in predicting acute kidney injury. All findings were confirmed when urinary IL-18 was adjusted for urinary creatinine. Urinary IL-18 correlated with duration of cardiopulmonary bypass (P < 0.001).
  
  
  CONCLUSIONS
  In adults, early postoperative measurement of urinary IL-18 appears not to be valuable in identifying patients who develop acute kidney injury after cardiac surgery, but rather represents a nonspecific marker of cardiopulmonary bypass-associated systemic inflammation.
authors.affiliation: Department of Intensive Care, Austin Health, Melbourne, 145 Studley Rd, Heidelberg 3084, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Haase
authors.forename: Rinaldo
authors.initials: R
authors.lastname: Bellomo
authors.forename: David
authors.initials: D
authors.lastname: Story
authors.forename: Piers
authors.initials: P
authors.lastname: Davenport
authors.forename: Anja
authors.initials: A
authors.lastname: Haase-Fielitz
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis / Q000209:etiology / Q000652:urine*; D000368:Aged; D015415:Biomarkers / Q000652:urine; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D020382:Interleukin-18 / Q000652:urine*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000209:etiology / Q000652:urine*; D011237:Predictive Value of Tests; D011446:Prospective Studies
chemical_list: D015415:Biomarkers; D020382:Interleukin-18