Diagnostic accuracy of serum cystatin C in chronic kidney disease: a meta-analysis

Background: Chronic kidney disease (CKD) is a major health problem worldwide with dramatically increasing incidence and prevalence. Serum cystatin C (sCysC) has been clarified by many studies as a relatively accurate marker to evaluate renal function. Study design: Meta-analysis of diagnostic test studies. Setting and population: Various clinical settings of CKD, including adult patients with diabetes, renal transplant patients, and so on. Selection criteria: A computerized search of PubMed, Cochrane clinical trial database, and Current Contents (from inception until June 16, 2014) was performed to identify potentially relevant articles. Index tests: Increased sCysC concentration. Reference tests: The measured glomerular filtration rate measured by nuclear medicine techniques such as Tc-99-diethylene triamine pentacaetic acid (Tc-99-DTPA) or Cr-51-ethylenediamine tetra-acetic acid (Cr-51-EDTA), or calculated by Cockcroft-Gault (CG) or Modification of Diet in Renal Disease (MDRD) formula or 24 hours creatinine clearance rate. Results: In total 19 studies were included in this study. Across all settings, the diagnostic odds ratio (DOR) of sCysC in predicting CKD was 40 (95% CI, 26 - 61) when sensitivity and specificity was 0.85 (95% CI, 0.81 - 0.89) and 0.87 (95% CI, 0.84 - 0.90), respectively. The area under the curve for the receiver-operating characteristic (AUROC) of sCysC to predict CKD was 0.92 (95% CI, 0.90 - 0.94). For the diagnostic value of sCysC in diabetics with CKD, the DOR was 51 (95% CI, 22 - 122), with sensitivity and specificity of 0.89 and 0.87, respectively. Subgroup analysis showed that sCysC was of better diagnostic value in the West than in Asia, and the diagnostic value of sCysC assayed by particle-enhanced nephelometric immunoassay (PENIA) was higher than sCysC assayed by particle-enhanced turbidimetric immunoassay (PETIA). Conclusion: SCysC appears to be a good biomarker in the definition of CKD. However, its performance is different in subgroups restricted by clinical settings, race, and sCysC assay.