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Uric acid and incident chronic kidney disease in a large health check-up population in Taiwan.
WANG, SHENGFENG 1; SHU, ZHENG 1; TAO, QIUSHAN 1; YU, CANQING 1; ZHAN, SIYAN 1; LI, LIMING 1*
[Miscellaneous Article] Nephrology. 16(8):767-776, November 2011.

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Aim: Uric acid (UA) is strongly associated with the confirmed chronic kidney disease (CKD) risk factors, such as hypertension, diabetes and metabolic syndrome (MS); however, whether higher UA is independently associated with CKD is still debatable. Other studies found that low UA level may reflect inadequate protection against oxidant-mediated stress; it is also unknown whether hypouricemia may have a harmful effect on the kidney. No studies have examined whether there is a J-shaped relationship between UA and incident CKD.

Methods: The association between UA and incident kidney disease (Glomerular filtration rate <60 mL/min per 1.73 m2) was examined among 94 422 Taiwanese participants, aged >=20 years with a mean 3.5 years follow-up in a retrospective cohort. The association between UA and CKD was evaluated using Cox models with adjustment for confounders.

Results: The adjusted hazard ratio (HR) for incident CKD was 1.03 (95% confidence interval (CI), 1.01 to 1.06) for baseline UA level (increase by 1 mg/dL). Compared with serum UA in the first quintile (2.0 to 4.5 mg/dL), the multivariate-adjusted HR for CKD of the fifth (>=7.3 mg/dL), fourth (6.3 to 7.2 mg/dL), third (5.5 to 6.2 mg/dL), second (4.6 to 5.4 mg/dL) and hyopuricemia (<2.0 mg/dL) were 1.15 (95%CI, 1.01-1.30), 0.98 (95%CI, 0.87-1.10), 1.06 (95%CI, 0.94-1.19), 1.02 (95%CI, 0.91-1.14) and 1.65(95%CI, 0.53-5.15), respectively. The tests for the non-linear association were all not significant for both male and female. Gender-specific model revealed only the UA above 7.3 mg/dL with the increased risk of new-onset CKD in males.

Conclusion: Hyperuricemia is a risk factor for CKD in Taiwan, future studies are still necessary to determine whether hypouricemia increases the risk of CKD.

SUMMARY AT A GLANCE: This paper uses a large cohort of Taiwanese to demonstrate an independent link between hyperuricemia and the development of CKD. This occurred independently of other components of the metabolic syndrome. The paper raises the possibility of hypouricemia also being a risk factor in a J-curve fashion.