Comparison of baseline Clinical and laboratory characteristics between healthy Control and CAD Patients
Baseline demographics, physical exam characteristics, and laboratory characteristics were listed in Table 1. There were significant higher serum Cystatin C, HCY, UA, LDL-C, and FPG in CAD patients than in healthy controls (all P < 0.05). Although there was no significant difference in gender and hypertension distribution between CAD patients and healthy controls, CAD patients had a significant higher in age and diabetes proportion and lower serum HDL (high-density lipoprotein cholesterol) and eGFR compared to healthy controls (all P < 0.05). However, no significant difference was found in BUN, TC and TG (All P>0.05).
Comparison of baseline Clinical and laboratory characteristics among different CAD patients
When comparing different variables among different type of CAD patients, the results showed that in AMI group, age, the proportion of male patients and hypertension and diabetes, TC, LDL-C, HCY, and Cystatin C were significant elevated than SAP group (all P < 0.05). The SAP group had the lowest mean levels of Cystatin C (1.1±0.9) and AMI group had the highest levels (1.6±0.6). HDL-C levels and eGFR were significantly higher in SAP group compared to AMI and UAP group (P < 0.05). However, no statistical differences were found in terms of SBP, DBP, FPG, BUN, UA, and TG (all P > 0.05) (Table 2).
In the UAP and AMI group, the serum Cystatin C level and HCY level were decreased with eGFR (P < 0.05). Further analysis showed that serum Cystatin C level was positively corelated with HCY level (r=0.65, p=0.001) and negatively correlated with eGFR (r=-0.632, p=0.031).
Baseline characteristics of CAD patients by Cystatin C Quartiles
Cystatin C grouping: The Cystatin C levels of all the CAD patients (682 cases) were divided into four subgroups according to the interquartile method: subgroup Q1, Cystatin C < 0.88 mg/L (161 cases); subgroup Q2, 0.88 mg/L ≤ Cystatin C < 1.09 mg/L (172 cases); subgroup Q3, 1.09 mg/L ≤ Cystatin C < 1.29 mg/L (178 cases); and subgroup Q4, Cystatin C ≥ 1.29 mg/L (171 cases).
The comparison of differences regarding Cystatin C quartiles among CAD patients revealed that the age, proportion of male patients and diabetes, HCY and Gensini score were significantly higher in Quartile fourth groups than in other groups (all P < 0.05) (Table 3). Of interesting,these data suggested that a remarkable increase in Gensini score with the increasing level of Cystatin C. Further analysis showed that serum Cystatin C level was positively corelated with Gensini score (r=0.55, p=0.021). These data suggested that a remarkable increase in Gensini score with the increasing level of Cystatin C. Neither group showed any significant differences in terms of FBG, TC, TG, HDL, and LDL.
Risk factors for coronary artery lesions
The multivariate logistic regression analysis was used to identify the independent risk factors for coronary artery lesions. The results showed that the significant risk factors included age (P = 0.042; OR = 2.33), the proportion of patients with hypertension (P = 0.001; OR = 2.17) and diabetes (P = 0.003; OR = 2.78) and Male (P = 0.004; OR = 2.27), as well as HCY (P = 0.03; OR = 1.43) (Table 4).
For the Cystatin C level, the ORs and 95% confidence intervals for coronary artery lesions were analyzed by Cystatin C quartiles. We adjusted for age, sex, distribution of hypertension and diabetes, and HCY before compared with the first (lowest) quintile. The odds rations (CI95%, P value) for coronary artery lesions were as follows: second quintile, 1.28 (0.89-1.85, p =0.18); third quintile, 1.52 (0.94-2.49, p = 0.09); and fourth quintile, 2.28(1.24-2.85, p =0.003). These data strongly suggested that increased serum Cystatin C levels were related with the severity of coronary artery lesions.