title: Cystatin C is correlated with mortality in patients with and without acute kidney injury.
abstract: BACKGROUND
  Recent research has shown cystatin C to predict mortality and cardiovascular morbidity independent of renal function. The aim of this study was to evaluate the prognostic value of cystatin C on mortality in adult general ICU patients with acute kidney injury (AKI). We later expanded the study and included patients without signs of AKI.
  
  
  METHODS
  A total of 845 ICU patients were analysed for cystatin C and classified according to the RIFLE criteria. Of these, 271 patients with either creatinine >150 micromol/l, urea >25 or anuria/oliguria entered the AKI cohort. The remaining 562 patients entered the non-AKI cohort. Both cohorts were divided into quartiles according to cystatin C at entry. In the non-AKI cohort, we split the highest cystatin C quartile into two. The relationship between the different cystatin C quartiles and mortality in patients with and without AKI was estimated by hazard ratios (HR) derived from the Cox proportional hazards regression model.
  
  
  RESULTS
  A relationship between cystatin C and mortality was found in patients with and without AKI, being stronger in patients without AKI. In AKI patients, the HR comparing cystatin C above and below the median more than doubled from the second year on compared to the first year follow-up. After exclusion of patients in the non-AKI cohort with 'potential AKI' (creatinine >100 micromol/l or urea > 20 mmol/l), the correlation between cystatin C levels and risk of death was strengthened.
  
  
  CONCLUSIONS
  Cystatin C is correlated with mortality independently of renal function measured by creatinine in patients entering the general ICU.
authors.affiliation: Department of Anaesthesiology and Intensive Care, Karolinska University Hospital, Solna, Sweden. max.bell@karolinska.se
authors.forename: Max
authors.initials: M
authors.lastname: Bell
authors.forename: Fredrik
authors.initials: F
authors.lastname: Granath
authors.forename: Johan
authors.initials: J
authors.lastname: Mårtensson
authors.forename: Erland
authors.initials: E
authors.lastname: Löfberg
authors.forename: Anders
authors.initials: A
authors.lastname: Ekbom
authors.forename: Claes-Roland
authors.initials: CR
authors.lastname: Martling
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood* / Q000401:mortality*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies
chemical_list: D055316:Cystatin C