Diagnostic value of serum cystatin C on newly diagnosed Parkinson's disease with mild cognitive impairment

Objective To investigate the diagnostic value of expression level of serum cystatin C (Cys-C) on early diagnosis of newly diagnosed Parkinson's disease with mild cognitive impairment (PD-MCI). Methods A total of 101 PD patients were divided into 2 groups: PD-MCI gruop (N = 43) and PD with normal cognition group (control group, N = 58). The levels of serum Cys-C, lipid, creatinine (Cr) and uric acid (UA) were tested. Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used to evaluate cognitive function, and Logistic regression analysis was used to evaluate the correlation between PD-MCI and the level of serum Cys-C. Receiver operating characteristic (ROC) curve was used to detect the sensitivity and specificity of early diagnosis. Results The expression level of serum Cys-C in PD-MCI group [(1.12 ± 0.10) mg/L] was higher than that of control group [(1.00 ± 0.15) mg/L, P = 0.000]. Univariate and multivariate Logistic regression analysis showed that serum Cys-C was the independent risk factor for PD-MCI (OR = 4.285, 95% CI: 1.301-14.112; P = 0.017); Spearman rank correlation analysis showed the expression level of serum Cys-C was negatively correlated with MMSE total score (rs = -0.831, P = 0.000), MoCA total score (rs = -0.848, P = 0.000), visuospatial/executive function (rs = -0.495, P = 0.001), attention/counting (rs = -0.339, P = 0.026) and delayed recall (rs = -0.307, P = 0.045). ROC curve analysis showed that area under the curve (AUC) was 0.707 (95%CI: 0.603-0.811, P = 0.000). Diagnostic sensitivity and specificity were 53.50% and 82.80% respectively, and the critical value of serum Cys-C level was 1.105 mg/L. Conclusions Increased expression level of serum Cys-C maybe closely related with newly diagnosed PD-MCI, and has a certain value to the early diagnosis of PD-MCI. DOI: 10.3969/j.issn.1672-6731.2015.08.007