Association between serum uric acid to serum creatinine ratio with cardiovascular and all-cause mortality in adults with hypertension

The serum uric acid to serum creatinine ratio (SUA/sCr) is a standardized index of renal function. More importance was attached to the significance of this ratio in the progression of hypertension. While the association between the prognosis of hypertension and SUA/sCr is unknown. Therefore, we aimed to prospectively examine the associations of serum uric acid to serum creatinine ratio and all-cause and CVD mortality in adults with hypertension. Participants with hypertension from NHANES 1999–2018 (n = 15,269) were included. They were stratified by 1 increment of SUA/sCr ratio and categorized into 6 groups as ≤ 4, > 4 to 5, > 5 to 6, > 6 to 7, > 7 to 8, and > 8. The reason for categorization in 6 groups was to analyze the influence of different ratios on outcomes accurately and provide more precise guidance. The sample size is large enough that even if divided into 6 groups, it does not affect the statistical power. The primary outcomes were all-cause and CVD mortality. Weighted multivariable Cox proportional hazards regression models were used to estimate hazard ratio (HRs) of mortality. Restricted cubic spline regression models were utilized to examine dose–response associations between the serum uric acid to serum creatinine ratio and all-cause and CVD mortality. Relatively comprehensive stratified analyses were conducted to confirm the accuracy and stability of the results. There were 15,269 total participants, 49.4% of whom were men, with an average age of 56.6 years. Weighted multivariable Cox proportional hazards regression models demonstrated participants in the lowest group (≤ 4) had the HRs (95% CIs) of 1.43 (1.18, 1.73) for all-cause mortality and 2.8 (1.92, 4.10) for CVD mortality when compared to the reference group. Participants in the highest group (> 8) had the HRs (95% CIs) of 0.47 (0.25, 0.89) for CVD mortality when compared to the reference group. There were progressively lower risks for all-cause and CVD mortality with the SUA/sCr ratio increased (both P trend < 0.01). The SUA/sCr ratio was (P for nonlinearity < 0.01) nonlinearly correlated with all-cause mortality, with inflection points of 6.25. In addition, the restricted cubic splines results indicated that the SUA/sCr ratio (P for nonlinearity = 0.32) showed linear and negative associations with cardiovascular mortality with inflection points of 6.54. The inverse associations between SUA/sCr ratio and all-cause mortality were consistent across all subgroups except for the subgroup of eGFR < 45 ml/min/1.73 m2 and never smokers (P trend = 0.20 and 0.13, respectively), and the inverse associations between low SUA/sCr ratio and CVD mortality were consistent across all subgroups (P trend < 0.01). Contrary to previous studies, outcomes suggest that lower SUA/sCr ratio was associated with higher risks of all-cause and CVD mortality in adults with hypertension.