Predictive value of serum cystatin C in kidney recipients with poor early graft ‎function

Despite improvements in surgical techniques and immunosuppression regimen, poor early graft function (PEGF) is a common problem among kidney recipient. PEGF has an effect on the short and long-term graft outcome. Its timely diagnosis, therefore, is of the main priorities. To date, an array of biochemical methods including classic routine- as well as innovative biomarkers has been utilized for the early diagnosis of PEGF. Of these, serum Cystatin C (SCys) has received the most attention. This study was undertaken to evaluate the diagnostic performance of SCys for the segregation between kidney recipients (KRs) with PEGF and GEGF (Good early graft function) using a Latex Enhanced Immunoturbidimetric (LETI) assay. In this prospective study, kidney recipients (n=39) were enrolled. Blood samples were collected at 15 -time points post kidney transplantation (post-KT). Demographic and clinical variables were collected. KRs segregated into: a) PEGF defined as dialysis requirement within the first week after operation and/or SCr≥1.70 mg/dl on 5th post -KT and b) GEGF defined as a SCr<1.70 mg/dl on 5th day Post-KT. SCys was measured on BT-1500 auto-analyzer using LEIT kit. Mann-Whitney U and independent T-test were used for evaluation of any difference between two studied groups. Fisher’s exact test was employed for the analysis of categorical variables. Evaluation of the diagnostic and predictive values were performed using receiver operating characteristic (ROC) analysis. The mean age of the KRs was 41.6±13.2 years. Distribution of male and female participants were 21 (53.8%) and 18 (46.1%). According to clinical criteria, 27 participants (69.2%) were classified as GEGF, whilst remaining 12 individuals (30.8%) were presented PEGF. Divergence between PEGF and GEGF was detected at 56 and 92 hrs post-surgery (p<0.05). Area under curve (AUC), cut-off value, sensitivity, specificity, positive predictive value and negative predictive value for SCys 56 hrs post-KT were 0.75, 2.72 mg/l, 66.7%, 74.1%, 53.3% and 83.3%a. The respective values for 92 hrs post-KT were 0.7, 2.64 mg/l, 75%, 70%, 52.9% and 86.4%, respectively. This study has revealed that differentiation between PEGF and GEGF with relatively high sensitivity and specificity was achieved at 54 and 92 hrs post-KT. Further investigations are needed to evaluate the relevance of these finding in clinical terms.