title: Persistent kidney injury at hospital discharge after cardiac surgery with cardiopulmonary bypass in patients with normal preoperative serum creatinine and normal estimated glomerular filtration rate.
abstract: OBJECTIVE
  Acute kidney injury is a serious complication after cardiac surgery. Although it resolves in most cases, a significant portion of patients persistently have raised creatinine values at hospital discharge. These patients are at greater risk for developing chronic kidney disease and mortality. Therefore, the present study aimed to ascertain risk factors of persistent acute kidney injury after cardiac surgery in patients with normal preoperative renal function.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Tertiary heart centers.
  
  
  METHODS
  2,181 adult cardiac surgical patients, predominantly Asian.
  
  
  METHODS
  Cardiac surgery between August 2008 and July 2012.
  
  
  RESULTS
  The incidence of acute kidney injury, as defined by the Acute Kidney Injury Network stage 1 criteria, was 21.7%. At discharge, 10.5% of these patients had persistent kidney injury, which was defined as a ≥ 26.4 μmol/L (≥ 0.3 mg/dL) difference between preoperative and discharge creatinine levels and/or a 50% rise in serum creatinine. These patients were more likely to be aged ≥ 70 years (relative risk = 2.232, 95% confidence interval = 1.326-3.757, p = 0.003), have a higher peak postoperative creatinine value within 48 hours (relative risk = 1.007, 95% confidence interval = 1.004-1.010, p<0.001), and have lower hemoglobin on intensive care unit arrival (relative risk = 0.759, 95% confidence interval = 0.577-0.998, p = 0.048).
  
  
  CONCLUSIONS
  Age ≥ 70 years, higher peak postoperative creatinine within 48 hours, and lower hemoglobin on intensive care unit arrival are associated with persistent acute kidney injury. Strategies to improve hemoglobin on intensive care unit arrival potentially can reduce persistent acute kidney injury. The authors recommend that patients aged ≥ 70 years undergo further renal evaluation for better risk stratification.
authors.affiliation: Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Roderica Rui
authors.initials: RR
authors.lastname: Ge Ng
authors.affiliation: Department of Anesthesia and Surgical Intensive Care, Singapore General Hospital, Singapore, Singapore; Cardiovascular and Metabolic Disorders, Duke-NUS Graduate Medical School, Singapore, Singapore.
authors.forename: Sophia Tsong
authors.initials: ST
authors.lastname: Huey Chew
authors.affiliation: Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Weiling
authors.initials: W
authors.lastname: Liu
authors.affiliation: Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore; Department of Anesthesia, National University Health System, Singapore, Singapore. Electronic address: lian_kah_ti@nuhs.edu.sg.
authors.forename: Lian
authors.initials: L
authors.lastname: Kah Ti
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood / Q000453:epidemiology*; D000367:Age Factors; D000368:Aged; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010351:Patient Discharge; D011183:Postoperative Complications / Q000097:blood / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D003404:Creatinine
keywords: acute kidney injury; age groups; anemia; cardiac surgical procedures; cardiopulmonary bypass; glomerular filtration rate; hemodilution