The Diagnostic Value Of Combining Serum Cystatin C With Creatinine For Contrast-induced Acute Kidney Injury And Its Clinical Implications:A Prospective Cohort Study

Background:Contrast-induced acute kidney injury?CI-AKI?,the third leading cause of hospital-acquired acute kidney injury?AKI?,was traditionally defined as an increase in serum creatinine?SCr?after contrast media exposure within 48-72 hours.This study was a prospective cohort study,aimed to find the diagnostic value of CysC alone or combined with SCr for CI-AKI and their clinical implications.Method:1071 patients undergoing coronary angiography?CAG?or percutaneous coronary intervention?PCI?from July 1,2013 to August 31,2014 were prospectively included.Patients requiring dialysis were excluded.CysC and SCr were assessed at baseline and 24-48 hours after contrast media exposure.CI-AKI_traditional was defined as a SCr increase?0.3mg/dl or 50%from baseline.Major adverse events?MAEs,including death,myocardial infarction,stoke,revascularization and dialysis?at 1 year were assessed.Results:CI-AKI_traditional developed in 25 patients?2.3%?.The incidence of CI-AKI_traditional rose significantly to 20.0%and 80.0%in patients of chronic kidney disease?CKD?stage 3 and stage 4-5.1-year follow-up was available in 1063 patients?99.2%?and MAEs occurred in 61 patients?5.7%?.By receiver operating characteristic?ROC?curve analysis,a CysC increase?15%was the optimal increment cut-off value for CI-AKI detection with a 80%sensitivity and a 83%specificity?Positive predictive value:9.6%;negative predictive value:99.4%?and occurred in 187 patients?17.4%?.Patients with a CysC increase?15%had a higher Mehran score?5.2±3.9 vs 4.4±3.4,P=0.004?and incidence of MAEs?12.4%vs 4.3%,P<0.001?.By multivariate logistic regression analysis,a CysC increase?15%was a significant predictor of MAEs at 1 year?adjusted odds ratio[OR]=3.04;95%confidence interval[CI],1.75 to 5.29;P<0.001?.Using the composite of CysC?increase?15%as positive,+?and SCr?increase?0.3mg/dl or 50%as positive,+?as CI-AKI_new,both CI-AKI low-risk group?CysC+/SCr-or CysC-/SCr+?and high-risk group?CysC+/SCr+?had higher Mehran risk score?4.3±3.4 vs 4.8±3.6 vs9.8±4.4,P<0.001?and incidence of MAEs?4.4%vs 9.8%vs 33.3%,P<0.001?,compared with non CI-AKI group.CI-AKI groups were significantly associated with MAEs at 1 year?Low-risk group:adjusted OR=2.38,95%CI:1.30 to 4.34,P=0.005;high-risk group:adjusted OR=16.56,95%CI:4.49 to 61.12,P<0.001?.Conclusions:A CysC increase?15%at 24-48 hours after contrast media exposure might have a better sensitivity and negative predictive value in the diagnosis of CI-AKI.The combination of CysC and SCr would be helpful for the risk stratification of MAEs.