U-shaped relationship between serum uric acid level and decline in renal function during a 10-year period in female subjects: BOREAS-CKD2

Hyperuricemia is a known risk factor for chronic kidney disease (CKD). However, the risk of CKD in subjects with hypouricemia remains controversial. The author Mori and colleagues (2020) conducted a study titled, “U-shaped relationship between serum uric acid level and decline in renal function during a 10-year period in female subjects: BOREAS-CKD2” published in “The Hypertension Research”. The summary of the study is below:

Objective:

To investigate the association of CKD risk with changing serum uric acid (UA) level as per sex and age of subjects in a general population.

Method:

The study enrolled 6,779 subjects (age 45 ±9 years) who received annual health checkups, out of the data from a 10-year follow-up. Exclusion criteria of the study were subjects with CKD at baseline and those who were taking anti-hyperuricemic drugs.

Findings:

In females, low serum levels of uric acid (UA) associated with an increased risk of CKD development. However, the mechanism for this relationship remains unclear. On the other hand, this U-shaped relationship was not found in male subjects. In the study, no interaction was supported between age and risk of CKD. In support of previous studies, this study also demonstrated that plasma xanthine oxidoreductase (XOR) activity is associated with obesity, liver dysfunction, smoking, hyperuricemia, insulin resistance, dyslipidemia, and adipokines.

Limitation:

There are chances of selection bias in the study as subjects were excluded due to changing their health checkup location. This affected data availability. Secondly, investigators were unable to identify new-onset of CKD every 3-4 months as the study was designed with subjects receiving an annual health checkup. The authors acknowledge that the study failed to conduct multivariate analysis as data for lifestyle factors were not obtained from subjects. Lastly, subjects with anti-hypertensive agents and/or anti-diabetic medications were not excluded; this might have affected the UA level and/or eGFR data.

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