Diagnostic value of cystatin C in acute kidney injury among patients with sepsis: a systematic review and meta-analysis

Introduction This study aimed to evaluate the diagnostic value of cystatin C (CysC) for the early detection of acute kidney injury (AKI) in patients with sepsis through a meta-analysis. Methods Relevant studies were systematically retrieved from electronic databases using predefined search terms, including “sepsis,” “acute kidney injury,” and “diagnosis.” Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. A random-effects meta-analysis was conducted using Stata 12.0 software to calculate pooled effect estimates and corresponding 95% confidence intervals (CIs). Subsequently, a summary receiver operating characteristic (SROC) curve was constructed, and the area under the curve (AUC) was calculated to evaluate overall diagnostic performance. Results A total of 17 studies on cystatin C for diagnostic testing were included, and a random-effects model was applied for meta-analysis. The results indicated that cystatin C exhibited good diagnostic performance for sepsis-associated acute kidney injury (SA-AKI), with an AUC of 0.88, sensitivity of 0.81, and specificity of 0.82. Subgroup analyses further demonstrated that studies based on the Sepsis 3.0 criteria showed higher specificity and diagnostic odds ratio (DOR), along with reduced heterogeneity. In addition, the combination of cystatin C with other biomarkers further improved diagnostic accuracy. Overall, these findings suggest that cystatin C is a promising biomarker for the early diagnosis of SA-AKI. Conclusion This meta-analysis demonstrates that cystatin C has considerable value for the early diagnosis of SA-AKI. Although heterogeneity among included studies remains, the overall evidence supports its potential applicability in clinical practice. Systematic review registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420251128608 , identifier PROSPERO (CRD420251128608).