Serum uric acid and the incidence of CKD and hypertension

Abstract

Background: Uric acid (UA) levels correlate positively with the prevalence of chronic kidney disease (CKD) and/or hypertension. We tested the hypothesis that UA may also have a link to a new incidence of CKD and hypertension.

Methods: Study design is a cohort study and the predictor is UA levels. Of the 15,470 screened cases, 8223 participants without CKD were eligible for the analysis of the incidence of CKD. Among these CKD candidates, 7569 participants were eligible for the analysis of the new development of hypertension. The observation period was 4 years.

Results: Relationship of UA with new cases of CKD. Higher UA levels had a closer association with the new development of CKD; 1.1 % (UA < 5 mg/dL), 1.5 % (5.0-5.9 mg/dL), 1.7 % (6.0-6.9 mg/dL), and 3.4 % (≧7 mg/dL), respectively (p < 0.001 by the Chi-square test). Cox proportional hazard analysis showed that the estimates of the CKD development were eGFR [Hazard Ratio (HR) 0.816, 95 % confidence intervals (CI) 0.791-0.840] and male gender (HR 0.562, 95 % CI 0.322-0.982). UA levels and new development of hypertension. Higher UA levels had a closer association with the new development of hypertension; 5.0 % (UA < 5 mg/dL), 8.9 % (5.0-5.9 mg/dL), 10.6 % (6.0-6.9 mg/dL), and 11.8 % (≧7 mg/dL), respectively (p < 0.001 by the Chi-square test). Cox proportional hazard analysis showed that the estimates of the hypertension development were BMI (HR 1.190, 95 % CI 1.155-1.226), age (HR 1.021, 95 % CI 1.010-1.032), HDL-cholesterol (HR 1.013, 95 % CI 1.007-1.019), male gender (HR 1.791, 95 % CI 1.338-2.395), UA level (HR 1.112, 95 % CI 1.024-1.207), and eGFR (HR 1008, 95 % CI 1.002-1.013). Furthermore, the logistic analysis showed that the odds ratio (OR) to estimate hypertension in the high UA group (UA ≧ 7 mg/dL; OR 1.33, 95 % CI 1.01-1.80) was greater than that in the low UA group (UA < 5 mg/dL). Kaplan-Meier analysis also confirmed the finding that the higher the UA levels the greater the hypertension development (p < 0.001 by the Log-rank test and Cox proportional hazard analysis).

Conclusion: High UA levels are associated with the new development of hypertension, but not with the incidence of CKD.

Keywords: CKD; Estimated glomerular filtration rate; Hypertension; Uric acid.

Fig. 1

New incidence of CKD at year 4. Newly onset of CKD was depicted at year 4 according to UA groups. The incidence rate increases significantly as UA levels increases (p < 0.001 by the Chi-square analysis)

Fig. 2

New development of hypertension at year 4. New onset of hypertension was depicted at year 4 according to UA groups. The incidence rate increases significantly as UA levels increases (p < 0.001 by the Chi-square analysis)

Fig. 3

Hypertension-free rate according to UA groups. The occurrence of hypertension in 4 years was presented according to UA groups. Each line has proven statistically different by the Log-rank test (p < 0.001)