Blood urea nitrogen and cardiovascular disease risk: Evidence from the CHARLS cohort study

Blood urea nitrogen (BUN) is an important biomarker reflecting renal function and has broad potential applications in predicting cardiovascular disease (CVD) and maintaining the heart-kidney balance. Therefore, this study aims to investigate the association between BUN levels and the incidence of new-onset cardiovascular disease in the general population aged 45 years and older, using data from a prospective cohort study. This study utilized data from waves 1 to 5 of the China Health and Retirement Longitudinal Study, including a total of 9886 participants aged 45 years and older. Specifically, a multivariable logistic regression model was applied to analyze the relationship between BUN levels and new-onset CVD. In addition, restricted cubic spline (RCS) analyses were conducted to assess potential nonlinear associations. During a follow-up period of up to 9 years, 1055 participants (10.67%) developed cardiovascular disease. Compared with individuals in the lowest quartile (Q1), those in the highest quartile (Q4) of BUN levels had a relatively lower risk of CVD (OR  = 0.83; 95% CI: 0.69-1.01), although the result was not statistically significant. RCS analysis did not reveal a clear dose-response relationship (P-overall = .0238; P-nonlinear = .0879), but a potential risk threshold was observed around a BUN level of 15.13 mg/dL. These findings indicate a potential association between BUN levels and new-onset CVD risk in adults aged 45 years and above. While this suggests that BUN might serve as an independent predictor, further validation is needed to establish its clinical utility. These results contribute to the growing body of evidence regarding cardiovascular risk factors and may inform future research on early screening and prevention strategies.