On the correlation between serum Cystatin C and Parkinson's disease in the Chinese population: a promising biomarker?

As there is no clear biomarker to diagnose Parkinson's disease, this meta-analysis aims to comprehensively evaluates the correlation between serum Cystatin C levels and Parkinson's disease in the Chinese population by the meta-analysis method. PubMed, Web of Science, Embase, Cochrane Library, China national knowledge infrastructure, and China WanFang databases were systematically searched on the correlation between serum Cystatin C and Parkinson's disease. The results showed that Cystatin C level in Parkinson's disease patients compared with the control group, the standardized mean difference = 1.78 (95% CI: 1.33 similar to 2.24, P < 0.05). The level of Cystatin C in the late Parkinson's disease stage compared with that in the mid-term of Parkinson's disease, the standardized mean difference was = 0.78 (95% CI: 0.08 similar to 1.49, P < 0.05). The Cystatin C level in the mid-term of Parkinson's disease compared with that in the early Parkinson's disease stage, the standardized mean difference was 1.24 (95% CI: 0.35 similar to 2.12, P < 0.05). The level of Cystatin C in Parkinson's disease with mild cognitive impairment compared with Parkinson's disease without mild cognitive impairment, the standardized mean difference was 1.29 (95% CI: 0.47 similar to 2.10, P<0.05). The differences were all statistically significant. In conclusion, a high level of serum Cystatin C may be involved in the occurrence and development of Parkinson's disease, whose level is higher in Parkinson's disease patients with mild cognitive impairment than that in Parkinson's disease without mild cognitive impairment. Therefore, Cystatin C in serum is a promising biomarker for diagnosing Parkinson's disease.