Elevated serum cystatin C at continuous renal replacement therapy initiation predicts lack of renal recovery

Background and objective: Serum cystatin C (sCyC) has been associated with renal function, and it rises earlier than creatinine after renal injury. However, its role in predicting renal recovery in critically ill patients after continuous renal replacement therapy (CRRT) remains untested. The study aimed to investigate the association of sCyC with renal recovery in critically ill patients requiring CRRT. Methods: Medical charts of AKI patients that had been admitted to a tertiary 15-bed intensive care unit from January 2006 to January 2008 were reviewed. Renal recovery was defined as the return to pre-morbid renal function (sCr < 1.5 x pre-morbid sCr), or as an improvement in RIFLE classification. Univariate analyses with t test or Wilcoxon Rank-Sum test were performed to screen predictors of renal recovery, and multivariate Logistic regression analysis was performed to identify independent predictors of renal outcome. Diagnostic performance of sCyC was assessed. Results: Younger age and lower sCyC values were independent predictors of renal recovery (OR: 0.96 and 0.58, respectively); the area under the receiver operating characteristic curve (AU-ROC) of sCyC in predicting renal recovery was 0.66 (95% CI: 0.51 - 0.81), with the sensitivity and specificity of 57.69% and 86.79% at the cutoff of 3.13 mg/l. Conclusion: Elevated cystatin C at CRRT initiation predicts lack of renal recovery, but its diagnostic performance is suboptimal. Our study was limited by the small sample size and the lack of strict protocols on the initiation and cessation CRRT.