Evaluating the Association of Clinical Cardiovascular Parameters and Metabolic Indices With Levels of Cystatin C in Early Middle Age

BACKGROUND: The pathophysiology of renal dysfunction requires population-based study. It is debatable in the literature whether cardiovascular metrics have an impact on cystatin C levels. METHODS: Using public-use biomarkers data of The National Longitudinal Study of Adolescent to Adult Health (Add Health) Wave 5 data, we tested, after adjusting for age (range: 32-42), anthropometrics (body mass index, waist circumference, and arm circumference), hemoglobin A1C, low-density lipoprotein, triglyceride, smoking, and sex, the association of 5 clinical cardiovascular measures (systolic blood pressure, diastolic blood pressure, mean arterial pressure, pulse pressure, and pulse rate) with cystatin C levels. Multiple linear regression analysis with a design-based approach was employed for data analysis after log-transformation of cystatin C levels. RESULTS: Our findings showed that there was no significant association between cystatin C levels and any of the previously mentioned cardiovascular parameters in this age group (P > 0.05). However, there was a significant association between cystatin C levels and age [exponentiated estimate (EE) (percent increase per unit) = 1.21; 95% confidence interval (CI) = 0.97-1.103, P < 0.0001], body mass index and waist circumference (EE = 0.702; 95% CI = 0.7-0.705, P < 0.0001), triglycerides level (EE = 0.02; 95% CI = 0.0199-0.0201, P = 0.01), smoking status [EE (compared with nonsmokers) = 8.98, 95% CI = 8.95-9.01, P < 0.0001], and female sex [EE (compared with males) = -5.92; 95% CI = -5.94 to -5.89, P < 0.0001]. CONCLUSIONS: Our findings clarify the impact of confounding factors, particularly age, on cystatin C levels. They also demonstrate how the significant correlation between cardiovascular parameters and cystatin C levels that were seen in earlier studies is largely affected by the age. Anthropometrics, age, lipid indices, and smoking should all be considered in clinical practice as possible reasons for increased cystatin C levels in otherwise healthy middle-aged individuals.