Cystatin C is correlated with mortality in patients with and without acute kidney injury.
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.
Bell
Max
M
Department of Anaesthesiology and Intensive Care, Karolinska University Hospital, Solna, Sweden. max.bell@karolinska.se
Granath
Fredrik
F
Mårtensson
Johan
J
Löfberg
Erland
E
Ekbom
Anders
A
Martling
Claes-Roland
CR
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
D055316:Cystatin C