Uric Acid in the Follow-Up Determines 30% Decline in Estimated GFR Over 2 Years: a Propensity Score Analysis

Disparity of serum uric acid threshold for CKD among hypertensive and non-hypertensive individuals

INTRODUCTION

Hypertension and rising serum uric acid (sUA) played a pivotal role in the development of Chronic Kidney Disease (CKD). This study investigates the interactive effect of sUA and hypertension on CKD and identifies the optimal threshold of sUA among individuals with and without hypertension in the Chinese community population.

MATERIALS AND METHODS

The study included 4180 individuals aged 45-85 years, derived from the China Health and Retirement Longitudinal Study (CHARLS) between 2011 and 2015. Additionally, a hospital-based study enrolled subjects in the Department of Nephrology at Zhongshan Hospital, China from January 1, 2019, to December 31, 2021. The interaction effect analysis were used to assess the impact of sUA and hypertension on CKD. We also compared the distribution of sUA and the CKD risk in community populations, distinguishing between those with and without hypertension. For the hospital-based population, kidney injury was marked by a KIM-1 positive area.

RESULTS

Our results indicate a higher prevalence of CKD in the community population with hypertension (10.2% vs. 3.9%, p < .001). A significant additive synergistic effects of the sUA and hypertension on the CKD risk were found. When the sUA level was < 4.55 mg/dL in the hypertensive population and < 5.58 mg/dL in the non-hypertensive population, the risk of CKD was comparable (p = .809). In the propensity score matched (PSM) population, the result remained roughly constant.

CONCLUSION

Therefore, even moderate levels of sUA was associated with a higher risk of CKD in middle-aged hypertensive patients, who warrant stricter sUA control.

Efficacy of dotinurad in patients with severe renal dysfunction

BACKGROUND

Although hyperuricemia is associated with the progression of chronic kidney disease (CKD), a reduction in CKD progression by uric acid (UA)-lowering therapy has been controversial. Recently, dotinurad, a uricosuric drug with selective urate reabsorption inhibitory properties, has been developed. However, its efficacy in lowering serum UA levels and its effects on renal function in patients with severe renal dysfunction are unclear. Thus, this study aimed to determine the effects of dotinurad on renal function in patients with severe renal dysfunction.

METHODS

Data from 53 outpatients with hyperuricemia who newly received dotinurad between December 2020 and October 2022 were retrospectively analyzed. The mean baseline estimated glomerular filtration rate (eGFR) was 38.7 ± 17.0 mL/min/1.73 m2. The patients were divided into three groups based on their baseline eGFR: eGFR < 30 (n = 17), 30 ≤ eGFR < 45 (n = 17), and eGFR ≥ 45 (n = 19).

RESULTS

The mean follow-up period was 9.8 ± 4.5 (range, 3-21) months. Serum UA levels significantly decreased in all groups. Although eGFR did not significantly change in patients with 30 ≤ eGFR < 45 and eGFR ≥ 45 (P = 0.918 and P = 0.535, respectively), it improved significantly in patients with eGFR < 30 (P = 0.032). The proportion of patients with improved eGFR was significantly higher in patients with eGFR < 30 (P = 0.038) than in patients with 30 ≤ eGFR < 45 and eGFR ≥ 45. In the multivariate logistic regression analysis, baseline eGFR < 30 and achieving a serum UA level of ≤ 6.0 mg/dL were significantly associated with improved eGFR (P = 0.033 and P = 0.015, respectively).

CONCLUSIONS

Dotinurad may have UA-lowering effects and the potential to improve kidney function in patients with severe renal dysfunction.

Effects of febuxostat on delaying chronic kidney disease progression: a randomized trial in China

BACKGROUND

A few studies have tested febuxostat for its usefulness in delaying chronic kidney disease (CKD) progression by treating hyperuricemia and results were controversial. Thus, we attempted to conduct a randomized controlled study using the Chinese population with advanced grade of CKD.

METHODS

One hundred CKD patients in stages 3 and 4 with asymptomatic hyperuricemia from seven medical centers were included in this prospective randomized controlled study and assigned to the control and febuxostat group, the latter of which received febuxostat to titrate to achieve serum uric acid (SUA) < 6 mg/dL. The observation period was 12 months. The primary outcomes included the event of estimated glomerular filtration rate (eGFR) decline ≥ 30% or 50% from baseline at 12 months, dialysis and death from CKD; secondary outcome was the change in eGFR. Safety analysis was also performed.

RESULTS

Forty-seven patients and 45 patients in the febuxostat and control groups, respectively completed the study. Seven of 47 (14.9%) participants reached 30% decline in eGFR in the febuxostat group, while 1 (2.1%) and 2 (4.3%) patients reached 50% decline in eGFR or dialysis. Thirteen (28.9%), 10 (22.2%) and 3 (6.7%) of 45 patients reached primary kidney outcomes separately in the control group. The change in eGFR after 12 months from baseline in the febuxostat group was 0.50 mL/min/1.73 m², which was significantly higher than that in the control group - 4.46 mL/min/1.73 m² (p = 0.006). Adverse events did not differ between two groups.

CONCLUSIONS

Febuxostat effectively slowed eGFR decline in patients with CKD stages 3 and 4 and asymptomatic hyperuricemia.

A longitudinal analysis of the relationship between serum uric acid and residual renal function loss in peritoneal dialysis patients

Background: Hyperuricemia occurs frequently in patients with continuous ambulatory peritoneal dialysis (CAPD). This study aimed to evaluate the impact of serum uric acid (UA) over time on residual renal function (RRF) loss in a cohort of patients with CAPD.Methods: A total of 201 patients who started CAPD therapy between January 1, 2008 and April 30, 2016 were included in this single-center, retrospective cohort study. All patients were followed up until December 31, 2016. The median follow-up time was 23.43 ± 16.60 months. RRF loss was represented as the time to anuria.Results: Eighty-six patients developed anuria within 5 years. Multivariate Cox regression analysis showed that time-averaged serum UA and peritonitis were independent risk factors for RRF loss, while weekly Kt/V urea was a protective factor. Cox proportional hazard regression models showed that both patients with time-averaged uric acid (TA-UA) < 6.77 mg/dL [hazard ratio (HR) = 1.165, 95% confidence interval (CI) 1.054-1.387; p < 0.05] and those with TA-UA≥ 7.64 mg/dL (HR = 1.184, 95% CI 1.045-2.114; p < 0.05) had a higher risk of RRF than those with TA-UA in the range of 6.77-7.64 mg/dL. Penalized spline smoothing also showed a U-shaped relationship between continuous UA and RRF loss.Conclusion: The present study demonstrated that both high and low serum UA over time were associated with RRF loss in patients with CAPD.

Association Between Serum Uric Acid and Depression in Patients with Chronic Kidney Disease not Requiring Kidney Dialysis: Cross-Sectional and Longitudinal Analyses

BACKGROUND Depression is the main problem of psycho-nephrology. We aimed to investigate clinical risk factors for depression in patients with non-dialysis chronic kidney disease (CKD). MATERIAL AND METHODS A non-dialysis CKD cohort study was conducted with 223 patients. Information on demographic and clinical parameters was collected at baseline. Beck Depression Inventory (BDI) and Pittsburgh Sleep Quality Index (PSQI) questionnaires were used to estimate depression and sleep quality in the patients. The questionnaires were repeated in 158 patients after 6 months. Logistic regression was performed to identify independent factors associated with depression and any longitudinal changes in BDI scores. RESULTS At baseline, 17 patients (7.72%) in the CKD cohort presented with depression. Multivariate logistic regression revealed that being female (odds ratio [OR] 0.319, 95% confidence interval [CI] 0.108 to 0.944, P=0.039) and having lower levels of serum uric acid (SUA) (OR 0.675, 95% CI 0.469 to 0.970, P=0.034) were independent risk factors for depression. A decrease in PSQI score (OR 0.873, 95% CI 0.777 to 0.981, P=0.022) and an increase in SUA level (OR 1.383, 95% CI 1.115 to 1.715, P=0.003) were independently associated with decline in BDI scores in the patients in the 6-month follow-up group. CONCLUSIONS Lower SUA levels and being female were independent risk factors for depression in non-dialysis CKD patients. Improving sleep quality and increasing SUA levels may relieve depression to some extent.

Genetically Elevated Serum Uric Acid and Renal Function in an Apparently Healthy Population

BACKGROUND

The association between uric acid and kidney disease has been extensively investigated. Numerous studies have reported the association between circulating levels of uric acid and renal function.

OBJECTIVES

To test, by the Mendelian randomization method, whether there is a causal association between circulating levels of uric acid and renal function.

METHODS

In 989 participants, estimated glomerular filtration rate (eGFR) was calculated, the circulating level of uric acid was tested, and the uric acid polymorphism (rs11722228) was genotyped.

RESULTS

After adjusting for age, gender, smoking history, alcohol intake, antihypertensive medication, body mass index, waist-to-hip ratio, and levels of urea nitrogen and creatinine, a significant allelic difference was found in uric acid levels for each genotype (p < 0.0001). Furthermore, the circulating levels of uric acid were negatively associated with eGFR after adjusting for cardiovascular risk factors and other potential confounders (p < 0.0001). Meanwhile, eGFR was significantly associated with the genotypes of rs11722228 (β = -0.07; p = 0.02).

CONCLUSIONS

Evidence from the Mendelian randomization approach implied a causal relationship between uric acid and renal function in an apparently healthy population.