The association between serum lead concentration and all-cause or cardiovascular disease mortality in hypertensive patients

Background The purpose of this study was to examine the relationship between serum lead levels and mortality in a hypertensive population in the United States. Methods and results In our study, 8364 subjects aged 20 years and older were included. We used a weighted COX proportional risk regression model to calculate risk ratios (HR) and 95% confidence intervals (CI) for blood lead and mortality. The relationship between serum lead levels and mortality was described by a restricted cubic spline curve. Kaplan Meier curves were used to describe the relationship between survival time and survival in study subjects, and all-cause mortality was analyzed in subgroups. Using the lowest quartile (Q1) as a reference, the HRs for all-cause mortality in model 3 (Q2, Q3, and Q4) were 1.05 (95% CI, 0.84-1.32), 1.10 (95% CI, 0.89-1.36), and 1.44 (95% CI, 1.16-1.79), respectively. For cardiovascular mortality, they were 1.03 (95% CI, 0.62-1.52), 1.30 (95% CI, 0.77-2.21), and 1.97 (95% CI, 1.31-2.97), respectively. Weighted restricted cubic spline regression confirmed a positive correlation between serum lead levels and risk ratio (HR) (P-overall < 0.001). Weighted Kaplan Meier curves showed a significant downward trend in survival in the hypertensive population with increasing serum lead levels. (P<0.0001 for all log-rankings). Subgroup analysis of all-cause mortality showed a strong positive association between serum lead levels and all-cause mortality in different populations. Conclusions Serum lead concentration showed a non-linear positive correlation with all-cause mortality and cardiovascular mortality in hypertensive patients.