Cystatin C as an early marker of acute kidney injury and predictor of mortality in the intensive care unit after acute myocardial infarction.

INTRODUCTION

Early detection of Acute Kidney Injury (AKI) is important. We conducted a prospective observational study to test the ability of cystatin C (CysC) to predict AKI and mortality among in intensive care unit (ICU) patients after acute myocardial infarction (MI).

METHODS

One hundred patients were enrolled in this study, CysC and serum creatinine (SCr) were measured at admission in the ICU and then daily for three days.We assessed the ability of CysC and SCr at admission to predict sustained AKI and short-term mortality at one month using the area under the receiver operator characteristic curve (AUC).

RESULTS

The mean relative increase in CysC after 24 hours was significantly higher than the mean relative increase in SCr (83±66% versus 14±48%; P>0.001).Of 100 patients, 35 patients had >50% increase in either CysC or SCr, seven patients had >50% increase in both markers and 58 patients had neither. CysC increased prior to elevation of SCr more frequently than the reverse (P > 0.0001). Baseline CysC was a good predictor of sustained AKI with an AUC of 0.86 (95% CI; 0.79-0.95), while the AUC of SCr was only 0.54 (95% CI; 0.40-0.69).Baseline CysC was a fair predictor of death with an AUC of 0.76 (95% CI; 0.65-0.87), while the AUC of SCr was only 0.65 (95% CI; 0.50-0.79).

CONCLUSION

CysC was an effective and earlier surrogate marker of decreased renal function than SCr in ICU population after MI. High CysC concentrations predict substantially increased risks of short-term mortality in the ICU after MI.