Prevention of kidney function decline using uric acid-lowering therapy in chronic kidney disease patients: a systematic review and network meta-analysis

Efficacy and Safety of Allopurinol on Chronic Kidney Disease Progression: A Systematic Review and Meta-Analysis

OBJECTIVE

Hyperuricemia is associated with the progression of chronic kidney disease (CKD). Whether urate-lowering treatment with allopurinol can delay disease progression remains controversial.

METHODS

Relevant databases were searched. Randomized clinical trials comparing the efficacy and -safety of allopurinol in patients with CKD were selected. The primary outcomes were changes in serum uric acid concentration and estimated glomerular filtration rate (eGFR). Random-effects modeling was used to -calculate the standard mean difference (SMD) with 95% CIs.

RESULTS

Four trials enrolling 698 participants were included. All were 2-arm parallel trials with a mean duration follow-up of 22.5 months. Congenital anomalies of the kidney and urinary tract were the most common cause of CKD in children, whereas diabetes was the leading cause of CKD in adults. Allopurinol significantly increased the eGFR compared with control groups (SMD, 2.04; 95% CI, 0.60-3.49; p = 0.005; I2 = 98.23%). Allopurinol led to a significant decrease in serum uric acid concentration compared with the control group (SMD, -5.16; 95% CI, -8.31 to -2.01; p = 0.001; I2 = 98.80%). No significant difference in adverse effects was identified between treatment and control groups.

CONCLUSIONS

Allopurinol treatment in patients with CKD and hyperuricemia slows the decline in eGFR as compared with placebo, without risk of increased adverse effects.

Association of platelet to high-density lipoprotein cholesterol ratio with hyperuricemia

The platelet/high-density lipoprotein ratio (PHR) has been identified as a significant indicator of inflammation and a hypercoagulable state, demonstrating a strong link with the severity of nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome (MetS). However, its correlation with hyperuricemia has not yet been documented. This study utilized a cross-sectional design, analyzing data collected from the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2016 in the United States. The platelet/high-density lipoprotein ratio (PHR) was determined by dividing the number of platelets (PLT) by the level of high-density lipoprotein cholesterol (HDL-C). We employed multivariable logistic regression analyses, generalized additive models, and subgroup analyses to investigate the correlation between PHR and hyperuricemia. The study revealed a hyperuricemia prevalence of 18.56%. Analysis indicated a significant positive correlation between PHR and the risk of hyperuricemia (OR 1.11, 95% CI 1.08, 1.14). This correlation remained consistent across different subgroups including age, ethnicity, gender, and body mass index (BMI). Smooth curve fitting demonstrated a saturation effect between PHR and the risk of hyperuricemia. PHR is positively correlated with hyperuricemia and may serve as a novel biomarker for predicting the onset of this condition. Additionally, targeted interventions to improve PHR might help reduce the incidence of hyperuricemia.

Effect of uric acid reduction on chronic kidney disease. Systematic review and meta-analysis

Accumulating evidence suggests that hyperuricemia is a pathological factor in the development and progression of chronic kidney disease. However, the potential benefit afforded by the control of uric acid (UA) is controversial. Individual studies show discrepant results, and most existing meta-analysis, especially those including the larger number of studies, lack a placebo or control group as they aim to compare efficacy between drugs. On these grounds, we performed a me-ta-analysis restricted to studies including the action of any anti-gout therapies referenced to a control or placebo arm. This approach allows for a clearer association between UA reduction and renal effect. Of the twenty-nine papers included, most used allopurinol and febuxostat and, therefore, solid conclusions could only be obtained for these drugs. Both were very effective in reducing UA, but only allopurinol was able to significantly improve glomerular filtration rate (GFR), although not in a dose-dependent manner. These results raised doubts as to whether it is the hypouricemic effect of anti-gout drugs, or a pleiotropic effect, what provides protection of kidney function. Accordingly, in a correlation study that we next performed between UA reduction and GFR improvement, no association was found, which suggests that additional mechanisms may be involved. Of note, most trials show large inter-individual response variability, probably because they included patients with heterogeneous phenotypes and pathological characteristics, including different stages of CKD and comorbidities. This highlights the need to sub classify the effect of UA-lowering therapies according to the pathological scenario, in order to identify those CKD patients that may benefit most from them. Systematic Review Registration: CRD42022306646 https://www.crd.york.ac.uk/prospero/.

A Possible Therapeutic Application of the Selective Inhibitor of Urate Transporter 1, Dotinurad, for Metabolic Syndrome, Chronic Kidney Disease, and Cardiovascular Disease

The reabsorption of uric acid (UA) is mainly mediated by urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) in the kidneys. Dotinurad inhibits URAT1 but does not inhibit other UA transporters, such as GLUT9, ATP-binding cassette transporter G2 (ABCG2), and organic anion transporter 1/3 (OAT1/3). We found that dotinurad ameliorated the metabolic parameters and renal function in hyperuricemic patients. We consider the significance of the highly selective inhibition of URAT1 by dotinurad for metabolic syndrome, chronic kidney disease (CKD), and cardiovascular disease (CVD). The selective inhibition of URAT1 by dotinurad increases urinary UA in the proximal tubules, and this un-reabsorbed UA may compete with urinary glucose for GLUT9, reducing glucose reabsorption. The inhibition by dotinurad of UA entry via URAT1 into the liver and adipose tissues increased energy expenditure and decreased lipid synthesis and inflammation in rats. Such effects may improve metabolic parameters. CKD patients accumulate uremic toxins, including indoxyl sulfate (IS), in the body. ABCG2 regulates the renal and intestinal excretion of IS, which strongly affects CKD. OAT1/3 inhibitors suppress IS uptake into the kidneys, thereby increasing plasma IS, which produces oxidative stress and induces vascular endothelial dysfunction in CKD patients. The highly selective inhibition of URAT1 by dotinurad may be beneficial for metabolic syndrome, CKD, and CVD.

Asymptomatic Hyperuricemia: A Nephro-Rheumatological Perspective

Hyperuricemia (HU) is a common disorder associated with gout, kidney injury, and high cardiovascular risk. However, whether high serum uric acid (sUA) is a causative factor or just comorbidity remains unclear. When asked if asymptomatic hyperuricemic patients need treatment, even artificial intelligence in the form of the GPT chat provides an ambivalent answer and refers us to a healthcare provider. We believe that such discrepancies stem from an incomplete understanding of the role that uric acid (UA) plays inside and outside the cell. With the rapid development of genomics, proteomics, immunology, and novel biomarkers, we are armed with new data to help us better understand the weight of inborn and environmental factors on an individual's UA concentrations. This review sums up the latest progress that has been made in the field of asymptomatic HU, compares the results presented by various research teams, and indicates new directions that emerge for future studies.

Central diastolic blood pressure, plasma aldosterone and uric acid are associated with microalbuminuria in essential hypertension: a case-control study

OBJECTIVE

To study the development of microalbuminuria (MAU) in essential hypertension (EHT), we investigated the association of MAU with central blood pressure (CBP), direct renin concentration (DRC), plasma aldosterone (PA), and uric acid (UA).

METHOD

We determined 24 h-urinary albumin excretion (24 h-UAE) in patients with EHT who were hospitalized at TEDA International Cardiovascular Hospital from June 2020 to May 2022. We defined MAU as 24 h-UAE in the range of 30 mg/24 h to 300 mg/24 h. Univariate and multivariate analyses were conducted to determine the associations of MAU with CBP, DRC, PA, and UA in EHT, considering demographic and clinical information. We also plotted receiver operating characteristic curves (ROCs) for predicting MAU using these results.

RESULTS

More than a quarter of patients (26.5%, 107/404, 95% CI: 22.2-31.1%) were diagnosed with MAU in EHT. A higher body mass index (BMI), longer duration of hypertension, and higher severity were associated with MAU. Also, nearly 10% more creatinine levels were recorded in the MAU group than in the control group (69.5 ± 18.7 µmol/L vs. 64.8 ± 12.5 µmol/L, P = 0.004). The increase was also observed for PA (15.5, 9.7-20.6 ng/dL vs. 12.3, 9.0-17.3 ng/dL, P = 0.024) and UA (419.8 ± 105.6 µmol/L vs. 375.1 ± 89.5 µmol/L, P < 0.001) in the MAU group compared to that in the control group. Several variables were associated with MAU, including central diastolic blood pressure (CDBP) (OR = 1.017, 95% CI: 1.002-1.032, P = 0.027), PA (OR = 1.043, 95% CI: 1.009-1.078, P = 0.012) and UA (OR = 1.005, 95% CI: 1.002-1.008, P < 0.001). For MAU prediction, the area under the curve (AUC) was 0.709 (95% CI: 0.662-0.753; P < 0.001) when CDBP, PA, and UA were used in combination, and the optimal probability of the cut-off value was 0.337.

CONCLUSION

We found that CDBP, PA, and UA, used for MAU prediction, might be associated with its development during EHT.

GLUT9 as a potential drug target for chronic kidney disease: Drug target validation by a Mendelian randomization study

Although chronic kidney disease (CKD) is recognized as a major public health concern, effective treatment strategies have yet to be developed. Identification and validation of drug targets are key issues in the development of therapeutic agents for CKD. Uric acid (UA), a major risk factor for gout, has also been suggested to be a risk factor for CKD, but the efficacy of existing urate-lowering therapies for CKD is controversial. We focused on five uric acid transporters (ABCG2, SLC17A1, SLC22A11, SLC22A12, SLC2A9) as potential drug targets and evaluated the causal association between serum UA levels and estimated glomerular filtration rate (eGFR) using single-SNP Mendelian Randomization. The results showed a causal association between genetically predicted changes in serum UA levels and eGFR when genetic variants were selected from the SLC2A9 locus. Estimation based on a loss-of-function mutation (rs16890979) showed that the changes in eGFR per unit increase in serum UA level was -0.0082 ml/min/1.73 m2 (95% CI -0.014 to -0.0025, P = 0.0051). These results indicate that SLC2A9 may be a novel drug target for CKD that preserves renal function through its urate-lowering effect.

A Systematic Review and Meta-Analysis of the Association between Uric Acid and Allantoin and Rheumatoid Arthritis

Alterations in the circulating concentrations of uric acid and its degradation product, allantoin, might account for the systemic pro-oxidant state and the increased cardiovascular risk in rheumatoid arthritis (RA). We sought to address this issue by conducting a systematic review and meta-analysis of the association between the plasma/serum concentrations of uric acid and allantoin and RA. We searched PubMed, Scopus, and Web of Science from inception to 20 June 2023 for studies comparing plasma/serum concentrations of uric acid and allantoin between RA patients and healthy controls. We assessed the risk of bias with the JBI Critical Appraisal Checklist for analytical studies and the certainty of evidence with the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) Working Group system. In the 19 studies selected for analysis, there were non-significant differences in uric acid concentrations between RA patients and controls (standard mean difference, SMD = 0.11, 95% CI -0.07 to 0.30, p = 0.22; I2 = 87.9%, p < 0.001; low certainty of evidence). By contrast, the concentrations of allantoin were significantly higher in RA patients (SMD = 1.10, 95% CI 0.66 to 1.55, p < 0.001; I2 = 55.6%, p = 0.08; extremely low certainty of evidence). In meta-regression, a significant association was observed between the SMD of uric acid concentrations and body mass index, a risk factor for atherosclerosis and cardiovascular disease (t = 3.35, p = 0.007). Our study has shown a significant increase in the concentrations of the oxidative stress biomarker allantoin in patients with RA. Further research is warranted to investigate the interplay between uric acid, allantoin, redox balance, and cardiovascular disease in this group. (PROSPERO registration number: CRD42023441127).

Accumulation of Renal Fibrosis in Hyperuricemia Rats Is Attributed to the Recruitment of Mast Cells, Activation of the TGF-β1/Smad2/3 Pathway, and Aggravation of Oxidative Stress

Renal fibrosis is relentlessly progressive and irreversible, and a life-threatening risk. With the continuous intake of a high-purine diet, hyperuricemia has become a health risk factor in addition to hyperglycemia, hypertension, and hyperlipidemia. Hyperuricemia is also an independent risk factor for renal interstitial fibrosis. Numerous studies have reported that increased mast cells (MCs) are closely associated with kidney injury induced by different triggering factors. This study investigated the effect of MCs on renal injury in rats caused by hyperuricemia and the relationship between MCs and renal fibrosis. Our results reveal that hyperuricemia contributes to renal injury, with a significant increase in renal MCs, leading to renal fibrosis, mitochondrial structural disorders, and oxidative stress damage. The administration of the MCs membrane stabilizer, sodium cromoglycate (SCG), decreased the expression of SCF/c-kit, reduced the expression of α-SMA, MMP2, and inhibited the TGF-β1/Smad2/3 pathway, thereby alleviating renal fibrosis. Additionally, SCG reduced renal oxidative stress and mitigated mitochondrial structural damage by inhibiting Ang II production and increasing renal GSH, GSH-Px, and GR levels. Collectively, the recruitment of MCs, activation of the TGF-β1/Smad2/3 pathway, and Ang II production drive renal oxidative stress, ultimately promoting the progression of renal fibrosis in hyperuricemic rats.

Renoprotective effect of febuxostat on contrast-induced acute kidney injury in chronic kidney disease patients stage 3: randomized controlled trial

INTRODUCTION

Contrast-induced acute kidney injury (CI-AKI) is known to be a complication of using intravascular contrast injection. Unfortunately, it is associated with adverse outcomes such as prolonged length of hospitalization and increased burden of health care costs. So, we aimed to determine the efficacy of febuxostat in the prevention of contrast-induced acute kidney injury among patients with chronic kidney disease Stage 3 performing percutaneous coronary intervention (PCI).

METHODS

In a randomized controlled trial we enrolled 120 CKD stage 3 Patients with acute coronary syndrome referred to the cardiology department Ain-Shams University hospital for performing PCI and stenting. Patients were randomly assigned to two arms: Group I (study group): Included 60 patients who received Febuxostat added to the traditional treatment (IV hydration and N-acetylcysteine). The patients received Feburic 80 mg within 6-18 h before and within 6-18 h after the coronary intervention (a time gap of 24 h between two doses). Group II (control group): included 60 patients who received only traditional treatment.

RESULTS

The incidence of AKI was higher in the control group with a statistically significant difference. We found that Independent Significant risk factors that led to AKI were febuxostate avoidance, DM, high urea level, high creatinine level, CKD stage 3B, high Mehran score and high AKI risk.

CONCLUSION

We demonstrated that febuxostat has a Reno protective effect and it can help to reduce the incidence CI-AKI in CKD patients stage 3 performing PCI.

Cardiovascular and kidney outcomes of uric acid-lowering therapy in patients with different kidney functions: study protocol for a systematic review, pairwise and network meta-analysis

INTRODUCTION

Hyperuricaemia has been implicated in the development of kidney function in populations with chronic kidney disease; however, the benefits of urate-lowering therapy (ULT) remain uncertain in different clinical studies. The different kidney functions of enrolled populations and distinct pharmacokinetic characteristics of ULT might be of the essence for the contrasting results. In this study, we will synthesise all available data from randomised controlled trials (RCTs) and cohort studies, then evaluate the outcomes of ULT in patients stratified by different estimated glomerular filtration rate (eGFR) stratifications. Furthermore, we will attempt to explore a relatively optimal ULT regimen using a Bayesian network meta-analysis in different eGFRs.

METHODS AND ANALYSIS

We searched published and unpublished data from MEDLINE, EMBASE, the Cochrane Central Register of Controlled trials and ClinicalTrials.gov website (before March 2022) for RCTs and cohort studies without language restriction. In the pairwise meta-analysis, all regimens of ULT will be pooled as a whole and compared with controls in different eGFRs. The random-effects model will be applied to generate the summary values using the software Stata V.12.0 (StataCorp). Network meta-analysis within a Bayesian framework will be conducted to explore the relative efficacy profiles of different ULTs and to find optimal ULT in different eGFRs. The software of WinBUGS V.1.4.3 and R2WinBUGS package of R V.3.1.1 will be used in the network meta-analysis. Primary outcomes will be the occurrence of major cardiovascular events and kidney failure events. Secondary outcomes will include the rate of change in eGFR per year, all-cause death, changes in serum uric acid level and major adverse events. Two authors will independently review study selection, data extraction and quality assessment.

ETHICS AND DISSEMINATION

The meta-analysis does not require ethical certification. The results will be disseminated through publication in a peer-reviewed journal and through presentations at academic conferences.

PROSPERO REGISTRATION NUMBER

CRD42021226163.

The association among uric acid, microalbumin and estimated glomerular filtration rate in hypertensive patients: a case control study

OBJECTIVE

To estimate the relationship among uric acid (UA), 24-h microalbumin (24 h-MAU) and estimated glomerular filtration rate (eGFR) in hypertensive patients.

METHOD

The study enrolled adult patients hospitalized in TEDA International Cardiovascular Hospital. The study was used to explore the correlation among UA, 24 h-MAU and eGFR. Univariate analysis was used to compare continuous or categorical data groups according to data type. Multivariate analysis was used to explore the correlation among UA, Log 24 h-MAU and eGFR by linear regression, and the relationship among UA, 24 h-MAU ≥ 30 mg/24 h (increased 24 h-MAU) and eGFR < 90 ml·min^-1·1.73 m^-2 (mildly decreased eGFR) by logistic regression. Mediation effect analysis was used to explore the mediating effect of increased 24 h-MAU between UA and mildly decreased eGFR. Subgroup analysis was used to investigate the correlation among UA, 24 h-MAU and eGFR in different gender.

RESULT

Seven hundred and thirty-three inpatients were enrolled in the study, including 257 patients with hyperuricemia. The level of UA was 377.8 ± 99.9 μmol/L in all patients enrolled, and it was about 50.1% higher in hyperuricemia group (482.3 ± 58.8 μmol/L vs. 321.4 ± 63.5 μmol/L, P < 0.001). The prevalence of hyperuricemia was 35.1% (95%CI 31.6-38.5%). The univariate regression analysis showed that UA was significant related to Log 24 h-MAU, increased 24 h-MAU, eGFR and mildly decreased eGFR. After adjusted confounding factors, UA was significant related to Log 24 h-MAU (β = 0.163, P < 0.001), eGFR (β = - 0.196, P < 0.001), increased 24 h-MAU (quantitative analysis: OR = 1.045, 95%CI 1.020-1.071, P < 0.001; qualitative analysis: OR = 2.245, 95%CI 1.410-3.572, P = 0.001), but had no significant relationship with mildly decreased eGFR. Mediating effect analysis showed that increased 24 h-MAU partially mediated the relationship between UA and mildly decreased eGFR (relative indirect effect: 25.0% and 20.3% in quantitative analysis and qualitative analysis respectively). In the subgroup analysis, the results were stable and similar to the analysis for entry patients.

CONCLUSION

The prevalence of hyperuricemia was higher in hypertensive inpatients. UA was strongly associated with Log 24 h-MAU, eGFR and increased 24 h-MAU, while the correlation with mildly decreased eGFR was affected by multiple factors. And increased 24 h-MAU might be the intermediate factor between UA and mildly decreased eGFR.

Uric Acid and Chronic Kidney Disease: Still More to Do

Gout and hyperuricemia are present in 25% and 60% of patients with chronic kidney disease (CKD), respectively. Despite the common association, the role of uric acid in the progression of kidney disease and in metabolic complications remains contested. Some authorities argue that the treatment of asymptomatic hyperuricemia in CKD is not indicated, and some have even suggested hyperuricemia may be beneficial. Here, we review the various arguments both for and against treatment. The weight of the evidence suggests asymptomatic hyperuricemia is likely injurious, but it may primarily relate to subgroups, those who have systemic crystal deposits, those with frequent urinary crystalluria or kidney stones, and those with high intracellular uric acid levels. We recommend carefully designed clinical trials to test if lowering uric acid in hyperuricemic subjects with cardiometabolic complications is protective.

Factors associated with renal function state transitions: A population-based community survey in Taiwan

Background

Understanding renal function state transition risk and associated factors in community residences is vital for appropriate preventive and care actions. We aim to investigate factors affecting renal function state transitions through 10-year longitudinal community screening surveys.

Methods

The prospective cohort study included participants who attended the screening program ≥2 times from 2001 to 2009 and were divided into two cohorts: those with baseline estimated glomerular filtration rate (eGFR) ≥60 (n = 46,278) and those with eGFR 59-30 mL/min/1.73 m² (n = 4,656). We applied the illness-death model to identify associated factors with eGFR <60 and death for the cohort with baseline eGFR ≥60 and eGFR <30 and death for that with baseline eGFR ≥59-30.

Results

Among the followed-up participants, 3,018 (6.5%) in the cohort of baseline eGFR ≥60 mL/min/1.73 m² and 322 (6.9%) in the cohort of eGFR 59-30 mL/min/1.73 m² experienced renal function state transition during a median over 7-year follow-up. Besides eGFR and grade of proteinuria, diabetes mellitus (adding nearly 50% hazard rate) is the main factor associated with both state transitions. Other early-phase eGFR state transition risk factors were metabolic syndrome score, triglyceride, uric acid, fasting blood sugar, and high-density lipoprotein cholesterol. Males, poor hemoglobin, high triglyceride, and high low-density lipoprotein cholesterol were all linked with the late-phase eGFR state transition hazard rate.

Conclusion

The study developed the state transition functions for community participants with varying renal function levels. Further actions to develop precision screening plans and services that incorporate personal risk factors and state transition risks are necessary.

Chronic kidney disease: Which role for xanthine oxidoreductase activity and products?

The present review explores the role of xanthine oxidoreductase (XOR) in the development and progression of chronic kidney disease (CKD). Human XOR is a multi-level regulated enzyme, which has many physiological functions, but that is also implicated in several pathological processes. The main XOR activities are the purine catabolism, which generates uric acid, and the regulation of cell redox state and cell signaling, through the production of reactive oxygen species. XOR dysregulation may lead to hyperuricemia and oxidative stress, which could have a pathogenic role in the initial phases of CKD, by promoting cell injury, hypertension, chronic inflammation and metabolic derangements. Hypertension is common in CKD patients and many mechanisms inducing it (upregulation of renin-angiotensin-aldosterone system, endothelial dysfunction and atherosclerosis) may be influenced by XOR products. High XOR activity and hyperuricemia are also risk factors for obesity, insulin resistance, type 2 diabetes and metabolic syndrome that are frequent CKD causes. Moreover, CKD is common in patients with gout, which is characterized by hyperuricemia, and in patients with cardiovascular diseases, which are associated with hypertension, endothelial dysfunction and atherosclerosis. Although hyperuricemia is undoubtedly related to CKD, controversial findings have been hitherto reported in patients treated with urate-lowering therapies.

Update on Uric Acid and the Kidney

PURPOSE OF REVIEW

In this review, we report on new findings regarding associations of uric acid with kidney health. We discuss kidney stones, effects of uric acid in chronic kidney disease (CKD), and management of gout in CKD. Recent studies on neuroprotective effects of raising uric acid provide interesting data regarding nephrolithiasis.

RECENT FINDINGS

Elevated urate levels have been implicated in the progression of chronic kidney disease (CKD), but the results from PERL and CKD-FIX studies did not demonstrate that allopurinol slowed CKD progression. The SURE-PD3 sought to determine if increasing uric acid would slow the progression of Parkinson's disease. Results ultimately did not support this hypothesis, but high urinary uric acid levels caused uric acid stones, not calcium stones. Low urinary pH remains the key to the formation of uric acid stones. Thiazolidinediones improve insulin resistance, which is associated with an increase in urine pH. The most recent research has not supported the hypothesis that lowering serum uric acid levels will slow the progression of CKD or provide neuroprotection in Parkinson's disease. It is still unclear as to why uric acid stone formers have a high net acid excretion. The STOP-GOUT trial demonstrates that there was a lack of significant adverse events with higher urate-lowering dosages of allopurinol and febuxostat, despite patients' kidney function. This may push other studies to administer higher dosages per ACR guidelines. Future studies could then demonstrate decreased progression of CKD.