Nonlinear Association Between Serum Uric Acid Levels and Mortality in Maintenance Hemodialysis Patients: A Retrospective Study From the Beijing Hemodialysis Quality Control and Improvement Center.

BACKGROUND

To investigate the association between serum uric acid levels and the risks of all-cause and cardiovascular mortality in patients undergoing maintenance hemodialysis.

METHODS

Patients receiving maintenance hemodialysis registered in 2014 in the Beijing Blood Purification Quality Control and Improvement Center database were included. Patients were stratified into low (≤ 344 μmol/L), intermediate (344-464 μmol/L), and high (> 464 μmol/L) serum uric acid groups. Propensity score matching (1:1:1) was performed using age, sex, diabetes, and dialysis vintage. Survival was analyzed using Kaplan-Meier curves and the log-rank test. Cox proportional hazards models and restricted cubic spline analyses were applied to evaluate the associations between serum uric acid levels and all-cause and cardiovascular death.

RESULTS

We enrolled 2070 patients in three matched groups (n = 690 per group). The median follow-up was 64.0 (interquartile range, 31.1-72.0) months. All-cause death occurred in 292/690 (42.3%), 122/690 (17.7%), and 210/690 (30.4%) patients in the low-, intermediate-, and high-serum uric acid groups, respectively. After adjusting for multiple factors, the intermediate serum uric acid group had better survival than the low- (hazard ratio, 1.82; 95% confidence interval [95% CI], 1.41-2.34; p < 0.001) and high-serum uric acid groups (hazard ratio, 2.13; 95% CI, 1.64-2.76; p < 0.001). The pattern of cardiovascular death was consistent with that of all-cause mortality, showing higher risks in both the low- and high-serum uric acid groups compared with the intermediate-serum uric acid group. Further restricted cubic spline analyses suggested a U-shaped association between serum uric acid levels and the risks of all-cause and cardiovascular mortality, with the lowest mortality risk observed at serum uric acid levels of approximately 388-420 μmol/L.

CONCLUSION

Serum uric acid exhibited a U-shaped association with the risks of all-cause and cardiovascular death in patients undergoing maintenance hemodialysis. Both excessively low and high serum uric acid levels were associated with increased mortality risk.