Management of asymptomatic hyperuricaemia in patients with chronic kidney disease by Japanese nephrologists: a questionnaire survey

Rapid identification of early renal damage in asymptomatic hyperuricemia patients based on urine Raman spectroscopy and bioinformatics analysis

Objective: The issue of when to start treatment in patients with hyperuricemia (HUA) without gout and chronic kidney disease (CKD) is both important and controversial. In this study, Raman spectroscopy (RS) was used to analyze urine samples, and key genes expressed differentially CKD were identified using bioinformatics. The biological functions and regulatory pathways of these key genes were preliminarily analyzed, and the relationship between them as well as the heterogeneity of the urine components of HUA was evaluated. This study provides new ideas for the rapid evaluation of renal function in patients with HUA and CKD, while providing an important reference for the new treatment strategy of HUA disease. Methods: A physically examined population in 2021 was recruited as the research subjects. There were 10 cases with normal blood uric acid level and 31 cases with asymptomatic HUA diagnosis. The general clinical data were collected and the urine samples were analyzed by Raman spectroscopy. An identification model was also established by using the multidimensional multivariate method of orthogonal partial least squares discriminant analysis (OPLS-DA) model for statistical analysis of the data, key genes associated with CKD were identified using the Gene Expression Omnibus (GEO) database, and key biological pathways associated with renal function damage in CKD patients with HUA were analyzed. Results: The Raman spectra showed significant differences in the levels of uric acid (640 cm^-1), urea, creatinine (1,608, 1,706 cm^-1), proteins/amino acids (642, 828, 1,556, 1,585, 1,587, 1,596, 1,603, 1,615 cm^-1), and ketone body (1,643 cm^-1) (p < 0.05). The top 10 differentially expressed genes (DEGs) associated with CKD (ALB, MYC, IL10, FOS, TOP2A, PLG, REN, FGA, CCNA2, and BUB1) were identified. Compared with the differential peak positions analyzed by the OPLS-DA model, it was found that the peak positions of glutathione, tryptophan and tyrosine may be important markers for the diagnosis and progression of CKD. Conclusion: The progression of CKD was related to the expression of the ALB, MYC, IL10, PLG, REN, and FGA genes. Patients with HUA may have abnormalities in glutathione, tryptophan, tyrosine, and energy metabolism. The application of Raman spectroscopy to analyze urine samples and interpret the heterogeneity of the internal environment of asymptomatic HUA patients can be combined with the OPLS-DA model to mine the massive clinical and biochemical examination information on HUA patients. The results can also provide a reference for identifying the right time for intervention for uric acid as well as assist the early detection of changes in the internal environment of the body. Finally, this approach provides a useful technical supplement for exploring a low-cost, rapid evaluation and improving the timeliness of screening. Precise intervention of abnormal signal levels of internal environment and energy metabolism may be a potential way to delay renal injury in patients with HUA.

Association between circulating cystatin C and hyperuricemia: a cross-sectional study

INTRODUCTION/OBJECTIVES

Circulating cystatin C has reportedly been related to cardiovascular disease, diabetes, and metabolic syndrome, apart from its traditional role in estimating the glomerular filtration rate. However, whether circulating cystatin C is related to hyperuricemia remains unclear.

METHOD

We included 2406 men and 1273 women who attended their annual health checkups in this study. Anthropometric and biochemical parameters were measured. Hyperuricemia was diagnosed as fasting serum uric acid > 420 µmol/L in men and women.

RESULTS

A total of 695 (18.9%) participants were diagnosed with hyperuricemia. Hyperuricemic patients had significantly higher serum cystatin C levels than healthy controls (0.91 (0.83-1.02) versus 0.82 (0.72-0.92) mg/L, P < 0.001). Serum cystatin C levels were positively related to the prevalence of hyperuricemia, which was 5.18%, 14.76%, 22.66%, and 31.24% in participants with serum cystatin C levels in the first, second, third, and fourth quartiles, respectively (P < 0.001 for trend). In stepwise multivariate logistic regression analysis, participants with serum cystatin C in the fourth quartile had a more than twofold increased risk of hyperuricemia (OR 2.262, 95% CI 1.495-3.422; P < 0.001) compared with those with serum cystatin C in the first quartile. In subgroup analyses, the fourth quartile of cystatin C was related to increased risks of hyperuricemia in both non-obese and obese participants (OR 4.405, 95% CI 1.472-13.184, P = 0.008; OR 1.891, 95% CI 1.228-2.911, P = 0.004, respectively), in non-metabolic syndrome participants (OR 3.043, 95% CI 1.692-5.473; P < 0.001) but not in metabolic syndrome participants (OR 1.689, 95% CI 0.937-3.045; P = 0.081), and in non-non-alcoholic fatty liver disease (non-NAFLD) (OR 2.128, 95% CI 1.424-3.180; P < 0.001, respectively) and young and middle-aged participants (OR 2.235, 95% CI 1.492-3.348, P < 0.001) but not in NAFLD and elderly participants.

CONCLUSIONS

This study revealed a positive association of circulating cystatin C with hyperuricemia. Key Points • Serum cystatin C is associated with an increased risk of hyperuricemia. • Serum cystatin C is a useful biomarker in distinguishing patients at high risk of having hyperuricemia.

Factors associated with achieving target serum uric acid level and occurrence of gouty arthritis: A retrospective observational study of Japanese health insurance claims data

Purpose

This study assessed factors associated with achieving target serum uric acid (sUA) level and occurrence of gouty arthritis in Japanese clinical practice.

Methods

Japanese health insurance claims and medical check‐up data from October 2015 to March 2017 were analyzed to assess factors associated with target sUA achievement in gout and asymptomatic hyperuricemia and gouty arthritis in gout. Target sUA was further assessed by subgroup analysis of urate‐lowering therapy (ULT) prescriptions and outcomes, stratified by renal function.

Results

Patients achieving target sUA tended toward older, female, higher ULT dose, higher adherence, more comorbidities, and/or antidiabetic drugs prescribed. Renal dysfunction and/or diuretic prescriptions were associated with reduced achievement of target sUA. Severe renal dysfunction was particularly influential (odds ratio [OR] = 0.22 [95% confidence interval (CI): 0.10‐0.48] for <15, 0.15 [0.10‐0.23] for ≥15 to <30, compared with eGFR ≥90 mL/min/1.73 m²). Across all renal function categories, mean prescribed ULT dose was low (febuxostat 17.0‐21.0 mg/day, allopurinol 123.1‐139.6 mg/day), and target sUA achievement was reduced among renal dysfunction patients. Gouty arthritis was more likely in patients with a prior history of such occurrences, and less likely for higher ULT adherence, sUA monitored regularly at medical facilities, and/or more comorbidities.

Conclusion

In a real‐world setting, severe renal dysfunction is the most important risk factor for failure to achieve the target sUA, suggesting suboptimal disease management in patients with gout or hyperuricemia complicated by this condition. Findings associated with gouty arthritis suggest that these occurrences could be successfully managed by regular monitoring of sUA and closer adherence to ULT.

Physicians' perceptions of asymptomatic hyperuricemia in patients with chronic kidney disease: A questionnaire survey

Background

Hyperuricemia is associated with the development and progression of chronic kidney disease (CKD) as well as cardiovascular diseases. However, there is no consistent recommendation regarding the treatment of asymptomatic hyperuricemia (AHU) in CKD patients. Here, we surveyed Korean physicians’ perceptions regarding the diagnosis and management of AHU in CKD patients.

Methods

Questionnaires on the management of AHU in CKD patients were emailed to regular members registered with the Korean Society of Nephrology.

Results

A total of 158 members answered the questionnaire. Among the respondents, 49.4%/41.1% were considered hyperuricemic in male CKD patients whereas 36.7%/20.9% were considered hyperuricemic in female CKD patients when defined by serum uric acid level over 7.0/8.0 mg/dL, respectively. A total of 80.4% reported treating AHU in CKD patients. The most important reasons to treat AHU in CKD patients were renal function preservation followed by cerebro-cardiac protection. Majority of respondents (59.5%) thought that uric acid-lowering agents (ULAs) were the most effective method for controlling serum uric acid levels. Approximately 80% chose febuxostat as the preferred medication. A total of 32.3% and 31.0%, respectively, initiated ULA treatment if the serum uric acid level was more than 8.0 or 9.0 mg/dL, respectively. In addition, 39.2% and 30.4% answered that target serum uric acid levels of less than 6.0 or 7.0 mg/dL, respectively, were appropriate. The two major hurdles to prescribing ULAs were concerns of adverse reactions and the existing lack of evidence (i.e., the absence of Korean guidelines).

Conclusion

Most Korean physicians treat AHU in CKD patients to prevent CKD progression and cerebro-cardiovascular complications.

Achievement of Target Serum Uric Acid Levels and Factors Associated with Therapeutic Failure among Japanese Men Treated for Hyperuricemia/Gout

Objective To assess the rate of successfully achieving treatment goals among Japanese men with hyperuricemia/gout and identify factors influencing the success rate. Methods This cross-sectional study, conducted from January to December 2012, examined the serum uric acid (SUA) levels and clinical characteristics of 2,103 men with hyperuricemia/gout selected from an initial population of 136,770 individuals who participated in a workplace health checkup. The success rates (defined as SUA ≤6.0 mg/dL) were calculated, and a multivariate analysis was used to identify factors associated with "therapeutic failure" to achieve target SUA levels. Results The rate of successfully achieving the target SUA level was 37.5%. The body mass index (BMI) was significantly associated with therapeutic failure [25.0≤ Category (C) 2<27.5, adjusted odds ratio (AOR) =1.35; 27.5≤C3<30.0, AOR=1.69; C4 ≥ 30.0, AOR=1.94; relative to C1<25.0]. A significant positive association was also observed between waist circumference (WC) and therapeutic failure (85≤C2<90, OR=1.29; 90≤C3<95, OR=1.41; 95≤C4, OR=2.28; relative to C1<85.0 cm). Those with higher BMI/WC measurements were significantly more likely to have higher SUA levels than those with lower such measurements. The ongoing intake of dyslipidemia medication was identified as a protective factor against therapeutic failure. Discussion Our findings suggest a possible association between obesity and therapeutic failure, underscoring the importance of maintaining lipid profiles as part of managing SUA levels. Better management of both obesity and dyslipidemia may prevent future cardiovascular disorders by ensuring healthier SUA levels.

How should we manage asymptomatic hyperuricemia?

The definition of asymptomatic hyperuricemia remains unclear, as no consensus exists about the serum urate cutoff or the relevance of ultrasound findings. Comorbidities associated with hyperuricemia have increased in frequency over the past two decades. Hyperuricemia (and/or gout) may be a cause or a consequence of a comorbidity. Whereas epidemiological studies suggest that hyperuricemia may be linked to cardiovascular, metabolic, and renal comorbidities, Mendelian randomization studies have not provided proof that these links are causal. Discrepancies between findings from observational studies and clinical trials preclude the development of recommendations about the potential benefits of urate-lowering therapy (ULT) in individual patients with asymptomatic hyperuricemia. The risk/benefit ratio of ULT is unclear. The risk of developing gout, estimated at 50%, must be weighed against the risk of cutaneous and cardiovascular side effects of xanthine oxidase inhibitors. The need for optimal comorbidity management, in contrast, is universally accepted. Medications for comorbidities that elevate urate levels should be discontinued and replaced with medications that have the opposite effect. Therapeutic lifestyle changes, weight loss as appropriate, and sufficient physical activity are useful for improving general health. Whether ULT has beneficial effects on comorbidities will be known only when well-powered interventional trials with relevant primary endpoints are available.

Effect of uric-acid-lowering therapy on progression of chronic kidney disease: a meta-analysis

The efficacy and safety of uric-acid-lowering therapy (UALT) on slowing the progression of chronic kidney disease (CKD) accompanied by hyperuricemia were assessed. We searched Cochrane Library, PubMed, EMbase, CNKI, Wanfang and Vip databases up to November 15, 2012 for randomized controlled trials (RCTs) which compared the effect of UALT to control therapy in hyperuricemic patients secondary to CKD, and then performed quality evaluation and meta-analysis on the included studies. Seven RCTs involving 451 cases were included. UALT delayed the increase of serum creatinine (MD=-62.55 μmol/L, 95% CI: -98.10 to -26.99) and blood urea nitrogen (MD= -6.15 mmol/L, 95% CI: -8.17 to -4.13) as well as the decrease of glomerular filtration rate [MD=5.65 mL/(min·1.73 m2), 95% CI: 1.88 to 9.41], decreased systolic blood pressure (SBP) (MD= -6.08 mmHg, 95% CI: -11.67 to -0.49), and reduced the risk of the renal disease progression (RR=0.30, 95% CI: 0.19 to 0.46). However, there was no statistically significant difference in 24-h urinary protein quantity and diastolic blood pressure (P>0.05). We identified that UALT could delay the progression of CKD with secondary hyperuricemia. And this also indirectly proved that hyperuricemia was a risk factor for the CKD progression.

Four-week effects of allopurinol and febuxostat treatments on blood pressure and serum creatinine level in gouty men

The aim of this study was to observe the effects of uric acid lowering therapy (UALT), febuxostat and allopurinol, on blood pressure (BP) and serum creatinine level. Post-hoc data were derived from a phase-III, randomised, double-blind, 4-week trial of male gouty patients that compared the safety and efficacy of febuxostat and allopurinol in adults with gout. The subjects were randomly assigned to one of five groups, 35-37 in each group (febuxostat: 40, 80, 120 mg/d; allopurinol: 300 mg/d; control group: placebo). Blood pressure and serum creatinine level were measured at baseline and at weeks 2 and 4. Diastolic BP and creatinine level had decreased significantly in the UALT groups compared to the control group at week 4. Diastolic BP had decreased significantly in the allopurinol group and serum creatinine level had decreased significantly in the febuxostat groups at week 4. After adjusting for confounding variables, serum uric acid changes were found to be significantly correlated with changes in serum creatinine level but were not associated with changes in systolic or diastolic BP. UALT in gouty subjects significantly decreased diastolic BP and serum creatinine level. Changes in uric acid were significantly correlated with those in serum creatinine level, suggesting the feasibility of renal function improvement through UALT in gouty men.

Switching from allopurinol to febuxostat for the treatment of hyperuricemia and renal function in patients with chronic kidney disease

Hyperuricemia is a frequent complication of chronic kidney disease (CKD). Febuxostat is a novel xanthine oxidase inhibitor that is metabolized by many metabolic pathways in the kidney and the liver. We performed a 1-year cohort study of 73 hyperuricemic patients who had an estimated glomerular filtration rate (eGFR) below 45 ml/min and were being treated with urate-lowering therapy. In 51 patients, treatment was changed from allopurinol to febuxostat, and the other 22 patients were continued on allopurinol. The serum levels of uric acid (UA) level, creatinine, and other biochemical parameters were measured at baseline and after 3, 6, 9, and 12 months of treatment. The serum UA levels significantly decreased from 6.1 ± 1.0 to 5.7 ± 1.2 mg/dl in the febuxostat group and significantly increased from 6.2 ± 1.1 to 6.6 ± 1.1 mg/dl in the allopurinol group. The eGFR decreased 27.3 to 25.7 ml/min in the febuxostat group and from 26.1 to 19.9 ml/min in the allopurinol group. The switch from allopurinol to febuxostat was significantly associated with the changes in eGFR according to a multiple regression analysis (β = −0.22145, P < 0.05). Febuxostat reduced the serum UA levels and slowed the progression of renal disease in our CKD cohort in comparison with allopurinol.

Association between allopurinol and mortality among Japanese hemodialysis patients: results from the DOPPS

Purpose

Allopurinol, for treating hyperuricemia, is associated with lower mortality among hyperuricemic patients without chronic kidney disease (CKD). Greater allopurinol utilization in hemodialysis (HD) in Japan versus other countries provides an opportunity for understanding allopurinol-related HD outcomes.

Methods

Data from 6,252 Japanese HD patients from phases 1–3 of the Dialysis Outcomes and Practice Patterns Study (1999–2008) at ~60 facilities per phase were analyzed. Mortality was compared for patients prescribed (25 %) versus not-prescribed allopurinol using Cox regression, overall, and in patient subgroups.

Results

Patients prescribed allopurinol were more likely to be younger, male, and non-diabetic, and had higher serum creatinine and lower (treated) serum uric acid levels (mean = 7.0 vs. 8.0 mg/dL, p < 0.001). The inverse association between allopurinol prescription and mortality in unadjusted analyses (HR 0.65, 95 % CI 0.52–0.81) was attenuated by covariate adjustment (HR 0.84, 0.66–1.06). In subgroup analyses, allopurinol was associated with lower mortality among patients with no history of cardiovascular disease (CVD) (HR 0.48, 0.28–0.83), but not among patients with CVD (HR 1.00, 0.76–1.32). A similar pattern was seen outside Japan and for cardiovascular (CV)-related mortality.

Conclusions

Allopurinol prescription was not significantly associated with case-mix-adjusted mortality in Japanese HD patients overall, but was associated with lower all-cause and CV-related mortality in the subgroup of patients with no prior CVD history. These findings in HD patients may be related to findings in non-dialysis CKD patients showing lower CV event rates and mortality, and improved endothelial function with allopurinol prescription. These results are useful for designing future trials of allopurinol use in HD patients.

Risk factors for incident hyperuricemia during mid-adulthood in African American and white men and women enrolled in the ARIC cohort study

Background

Increased serum urate levels are associated with poor outcomes including but not limited to gout. It is unclear whether serum urate levels are the sole predictor of incident hyperuricemia or whether demographic and clinical risk factors also predict the development of hyperuricemia. The goal of this study was to identify risk factors for incident hyperuricemia over 9 years in a population-based study, ARIC.

Methods

ARIC recruited individuals from 4 US communities; 8,342 participants who had urate levels <7.0 mg/dL were included in this analysis. Risk factors (including baseline, 3-year, and change in urate level over 3 years) for 9-year incident hyperuricemia (urate level of >7.0 g/dL) were identified using an AIC-based selection approach in a modified Poisson regression model.

Results

The 9-year cumulative incidence of hyperuricemia was 4%; men = 5%; women = 3%; African Americans = 6% and whites = 3%. The adjusted model included 9 predictors for incident hyperuricemia over 9 years: male sex (RR = 1.73 95% CI: 1.36-2.21), African-American race (RR = 1.79 95% CI: 1.37-2.33), smoking (RR = 1.27, 95% CI: 0.97-1.67), <HS education (RR = 1.27, 95% CI: 0.99-1.63), hypertension (RR = 1.65, 95% CI: 1.30-2.09), CHD (RR = 1.57, 95% CI: 0.99-2.50), obesity (class I RR = 2.37, 95% CI: 1.65-3.41 and ≥ class II RR = 3.47, 95% CI: 2.33-5.18), eGFR < 60 (RR = 2.85, 95% CI: 1.62-5.01) and triglycerides (Quartile 4 vs. Quartile 1: RR = 2.00, 95% CI: 1.38-2.89). In separate models, urate levels at baseline (RR 1 mg/dL increase = 2.33, 95% CI: 1.94-2.80) and 3 years after baseline (RR for a 1 mg/dL increase = 1.92, 95% CI: 1.78-2.07) were associated with incident hyperuricemia after accounting for demographic and clinical risk factors.

Conclusion

Demographic and clinical risk factors that are routinely collected as part of regular medical care are jointly associated with the development of hyperuricemia.

Advanced kidney failure and hyperuricemia

Metabolic end products accumulate in kidney failure, including uric acid (UA), a terminal product of purine catabolism. Hyperuricemia (HUA) can cause gout and has been increasingly linked with cardiovascular (CV) morbidity and mortality, outcomes that are highly prevalent in patients with kidney disease. Serum UA levels rise as glomerular filtration declines, whereas the frequency of gouty attacks declines and the incidence of CV death rises precipitously. Herein, we review the kinetics of UA metabolism in CKD and dialysis and discuss the possible mechanisms of gout mitigation in kidney failure and the potential contribution of hyperuricemic milieu to CV outcomes in patients with kidney disease.

Efficacy and safety of febuxostat in patients with hyperuricemia and gout

The past decade has witnessed an exponential increase of novel therapeutic modalities for a variety of rheumatic disorders, including gout. During the past few years two novel therapeutic agents have been approved by the US Food and Drug Administration for the treatment of hyperuricemia in patients with gout, one of them being febuxostat, a nonpurine selective inhibitor of xanthine oxidase. Review of its pharmacokinetics and pharmacodynamics, efficacy and safety profile, and use in gout patients with comorbid conditions reveals that age and gender have no clinically significant effect and dose adjustments based on age or gender are not required. In addition, febuxostat can be used in patients with mild-to-moderate renal or hepatic involvement. Its overall efficacy and safety profile is comparable and, in certain subsets such as gout patients with mild and moderate renal insufficiency, is superior to allopurinol.