title: A new clinical multivariable model that predicts postoperative acute kidney injury: impact of endogenous ouabain.
abstract: BACKGROUND
  Acute kidney injury (AKI) is an important complication of cardiac surgery. Recently, elevated levels of endogenous ouabain (EO), an adrenal stress hormone with haemodynamic and renal effects, have been associated with worse renal outcome after cardiac surgery. Our aim was to develop and evaluate a new risk model of AKI using simple preoperative clinical parameters and to investigate the utility of EO.
  
  
  METHODS
  The primary outcome was AKI according to Acute Kidney Injury Network stage II or III. We selected the Northern New England Cardiovascular Disease Study Group (NNECDSG) as a reference model. We built a new internal predictive risk model considering common clinical variables (CLIN-RISK), compared this model with the NNECDSG model and determined whether the addition of preoperative plasma EO improved prediction of AKI.
  
  
  RESULTS
  All models were tested on >800 patients admitted for elective cardiac surgery in our hospital. Seventy-nine patients developed AKI (9.9%). Preoperative EO levels were strongly associated with the incidence of AKI and clinical complication (total ICU stay and in-hospital mortality). The NNECDSG model was confirmed as a good predictor of AKI (AUC 0.74, comparable to the NNECDSG reference population). Our CLIN-RISK model had improved predictive power for AKI (AUC 0.79, CI 95% 0.73-0.84). Furthermore, addition of preoperative EO levels to both clinical models improved AUC to 0.79 and to 0.83, respectively (ΔAUC +0.05 and +0.04, respectively, P < 0.01).
  
  
  CONCLUSIONS
  In a population where the predictive power of the NNECDSG model was confirmed, CLIN-RISK was more powerful. Both clinical models were further improved by the addition of preoperative plasma EO levels. These new models provide improved predictability of the relative risk for the development of AKI following cardiac surgery and suggest that EO is a marker for renal vascular injury.
authors.affiliation: Chair of Nephrology, Università Vita Salute San Raffaele, Milan, Italy Genomics of Renal Disease and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Simonini
authors.affiliation: Chair of Nephrology, Università Vita Salute San Raffaele, Milan, Italy Genomics of Renal Disease and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Lanzani
authors.affiliation: Anesthesia and Intensive Care Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy Università Vita Salute San Raffaele, Milan, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Bignami
authors.affiliation: Chair of Nephrology, Università Vita Salute San Raffaele, Milan, Italy Genomics of Renal Disease and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Nunzia
authors.initials: N
authors.lastname: Casamassima
authors.affiliation: Anesthesia and Intensive Care Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy Università Vita Salute San Raffaele, Milan, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Frati
authors.affiliation: Anesthesia and Intensive Care Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy Università Vita Salute San Raffaele, Milan, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Meroni
authors.affiliation: Chair of Nephrology, Università Vita Salute San Raffaele, Milan, Italy Genomics of Renal Disease and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Messaggio
authors.affiliation: Università Vita Salute San Raffaele, Milan, Italy Cardiac Surgery Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Ottavio
authors.initials: O
authors.lastname: Alfieri
authors.affiliation: Physiology Department, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: John
authors.initials: J
authors.lastname: Hamlyn
authors.affiliation: Department of Anesthesiology, Perioperative & Pain Medicine, Harvard Medical School, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Simon C
authors.initials: SC
authors.lastname: Body
authors.affiliation: Baylor St. Luke's Medical Center, Texas Heart Institute, Houston, TX, USA.
authors.forename: C David
authors.initials: CD
authors.lastname: Collard
authors.affiliation: Anesthesia and Intensive Care Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy Università Vita Salute San Raffaele, Milan, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Zangrillo
authors.affiliation: Chair of Nephrology, Università Vita Salute San Raffaele, Milan, Italy Genomics of Renal Disease and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Manunta
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood* / Q000453:epidemiology*; D000368:Aged; D019540:Area Under Curve; D015415:Biomarkers / Q000097:blood; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D003661:Decision Support Techniques; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D010042:Ouabain / Q000097:blood*; D011379:Prognosis; D018570:Risk Assessment; D012307:Risk Factors
chemical_list: D015415:Biomarkers; D010042:Ouabain
keywords: Na transport; acute renal failure; blood pressure; cardiovascular disease; renal injury