Relationship of uric acid with progression of kidney disease.

BACKGROUND: Uric acid levels are increased in patients with kidney dysfunction. We tested the hypothesis that uric acid may be associated with kidney disease progression. STUDY
DESIGN: Cohort study. SETTING & PARTICIPANTS: 5,808 participants of the Cardiovascular Health Study. PREDICTOR: Uric acid levels. OUTCOMES & MEASUREMENTS: Kidney disease progression was defined as a decrease in estimated glomerular filtration rate (GFR) of 3 mL/min/1.73 m(2) per year or greater (>or=0.05 mL/s) and as incident chronic kidney disease (CKD). Measures of kidney function were estimated GFR using the Modification of Diet in Renal Disease Study equation.
RESULTS: Higher quintiles of uric acid levels were associated with greater prevalences of estimated GFR less than 60 mL/min/1.73 m(2) (<1.00 mL/s) of 7%, 14%, 12%, 25%, and 42% for quintiles 1 (<or=4.41 mg/dL [<or=262 micromol/L]), 2 (4.41 to 5.20 mg/dL [262 to 309 micromol/L]), 3 (5.21 to 5.90 mg/dL [310 to 351 micromol/L]), 4 (5.91 to 6.90 mg/dL [352 to 410 micromol/L]), and 5 (>6.90 mg/dL [>410 micromol/L]), respectively. In comparison, there was only a modest, but significant, association between quintiles of uric acid levels and progression of kidney function decrease, with adjusted odds ratios of 1.0, 0.88 (95% confidence interval [CI], 0.64 to 1.21), 1.23 (95% CI, 0.87 to 1.75), 1.47 (95% CI, 1.04 to 2.07), and 1.49 (95% CI, 1.00 to 2.22) for quintiles 1 through 5, respectively. No significant association was found between uric acid level and incident CKD (adjusted odds ratio, 1.00; 95% CI, 0.89 to 1.14). LIMITATIONS: Measurements of albuminuria were not available.
CONCLUSIONS: Uric acid levels are associated strongly with prevalent CKD. In comparison, greater uric acid levels had a significant, but much weaker, association with progression of kidney disease.