Relationship of cystatin-C change and the prevalence of death or dialysis need after acute kidney injury: a meta-analysis

Aim: Cystatin-C (CysC) has been demonstrated as a sensitive and reliable biomarker to predict the onset of acute kidney injury (AKI). However, there are few studies concerned about the relationship between CysC and the outcomes of AKI. The aim of the present study was to determine whether CysC elevation prior to definite diagnosis of AKI is related to higher prevalence of death and dialysis need outcome.

Methods: A meta-analysis was conducted by searching PubMed, EMBASE and Cochrane Library database using the terms related to AKI combined with 'cystatin-C'. Bibliographies of relevant papers were reviewed manually. Eligible studies were those investigating death and dialysis need outcomes after AKI with CysC measurement, and were limited to English articles. Non-human studies were excluded. Random effect Mantel-Haenszel statistical method was used.

Results: Six studies were finally enrolled, consisting of 2332 patients. All of these studies were hospital-based prospective cohort studies. The follow-up duration varied from 5 days to 1 year. The odds ratio values for baseline CysC elevation and death as well as baseline CysC elevation and dialysis need were 2.34 (95% confidence interval [CI] 1.46-3.75) and 4.40 (95% CI 1.58-12.22), respectively (both P < 0.05).

Conclusion: Patients with CysC elevated prior to AKI diagnosis have higher risk to develop death and need dialysis during short- and long-term follow-up after AKI, thus having worse outcomes. This population deserves more careful observation and might benefit from more frequent follow-up visits in the clinic. Future work is needed to get a consensus cut-off value defining CysC elevation.