Effect of hyperuricemia and treatment for hyperuricemia in Japanese hemodialysis patients: A cohort study

Prevalence and clinical characteristics of hyperuricemia among patients with chronic kidney disease under haemodialysis in a tertiary care center: a cross-sectional study

Background

Hyperuricemia is common in chronic kidney disease patients. This study aimed to investigate the prevalence and clinical characteristics of hyperuricemia in patients with chronic kidney disease undergoing haemodialysis.

Materials and methods

This cross-sectional study was conducted among 104 patients with chronic kidney disease who visited the haemodialysis unit of a tertiary centre hospital from 11 September 2022, to 11 November 2022. A convenience sampling technique was used. The data were collected using a proforma form, entered into, and analyzed using the Statistical Package for Social Sciences version 21.

Results

The mean age group of the study participants was 54.02 ± 14.03 years, and around two-thirds were male (n=70, 67.3%). Almost half of the participants (50, 48.07%) had hyperuricemia with a mean uric acid level of 6.76 ± 2.62 mg/dl. The majority of the participants had associated hypertension (n=100, 96.2%). More than three-fourths of the respondents (83, 79.8%) had haemoglobin levels below the target range.

Conclusion

Nearly half of the study participants had hyperuricemia.

Moderate hyperuricaemia ameliorated kidney damage in a low-renin model of experimental renal insufficiency

Uric acid has promoted renal fibrosis and inflammation in experimental studies, but some studies have shown nephroprotective effects due to alleviated oxidative stress. We studied the influence of experimental hyperuricaemia in surgically 5/6 nephrectomized rats. Three weeks after subtotal nephrectomy or sham operation, the rats were allocated to control diet or 2.0% oxonic acid (uricase inhibitor) diet for 9 weeks. Then blood, urine and tissue samples were taken, and renal morphology and oxidative stress were examined. Inflammation and fibrosis were evaluated using immunohistochemistry and real-time PCR (RT-PCR). Remnant kidney rats ingesting normal or oxonic acid diet presented with ~60% reduction of creatinine clearance and suppressed plasma renin activity. Oxonic acid diet increased plasma uric acid levels by >80 μmol/L. In remnant kidney rats, moderate hyperuricaemia decreased glomerulosclerosis, tubulointerstitial damage and kidney mast cell count, without influencing the fibrosis marker collagen I messenger RNA (mRNA) content. In both sham-operated and 5/6 nephrectomized rats, the mast cell product 11-epi-prostaglandin-F_2α excretion to the urine and kidney tissue cyclooxygenase-2 (COX-2) levels were decreased. To conclude, hyperuricaemic remnant kidney rats displayed improved kidney morphology and reduced markers of oxidative stress and inflammation. Thus, moderately elevated plasma uric acid had beneficial effects on the kidney in this low-renin model of experimental renal insufficiency.

Serum Urate Levels of Hemodialyzed Renal Patients Revisited

OBJECTIVES

The need of maintaining serum urate (SU)-lowering agents in hemodialysis (HD) patients is an understudied area that requires a review, as it is a common practice. The aims were to assess the SU reduction achieved under HD and to analyze the kinetics of SU in a week of intermittent HD.

METHODS

The serum urate levels were determined before and after HD sessions in 96 consecutive patients with end-stage renal disease, and the average SU reduction was assessed. Variables related to HD were analyzed whether they were associated with SU reductions of 80% greater. In addition, a kinetics study was performed on 10 selected patients with hyperuricemia (SU before HD >6.8 mg/dL) throughout intermittent HD sessions in a 1-week period.

RESULTS

The mean ± SD age of the patients was 66.5 ± 13.8 years, and 62 of them were male (64.6%). The mean ± SD time on HD replacement was 7.1 ± 7.2 years, and 16 (16.4%) continued with urate-lowering agents. The mean SU reduction immediately after HD was 80.2% (95% confidence interval, 78.4-82.0); 51 patients (56.7%) showed SU reduction of 80% or greater. In the SU kinetics study, SU levels significantly reduced all over the period and persisted below hyperuricemia threshold (p = 0.015). Noteworthy, 6 patients (60%) were hyperuricemic before session 1, but only 1 (10%) before session 2 and none before session 3.

CONCLUSIONS

Under HD replacement therapy, the SU levels effectively reduced and persisted below saturation point, suggesting that the SU-lowering therapy would be unnecessary for patients on HD, but necessary in selected cases. The definition of hyperuricemia under HD needs to be revised.

Association of hyperuricemia and serum uric acid lowering therapy with mortality in hemodialysis patients

Introduction

In the general population, hyperuricemia is associated with increased morbidity and mortality. Data on this association in hemodialysis patients is controversial. Moreover, it remains elusive whether serum uric acid (SUA) lowering therapy is associated with mortality.

Methods

Retrospective analysis of 601 patients on chronic hemodialysis therapy in five outpatient centers with a maximum follow-up of 100 and a mean follow-up of 41 months. Death was defined as primary endpoint. Cumulative survival was analyzed by Kaplan–Meier analysis and Cox regressions adjusted for age.

Findings

Cumulative survival rates were higher for those subjects with a higher than median SUA concentration both based on mean annual and baseline measurements (p < 0.05 each). There was no survival difference anymore after adjustment for age (p > 0.05 each). Stratification for SUA lowering therapy (allopurinol/febuxostat) had no impact on cumulative survival, neither in Kaplan Meier nor in Cox regression analyses (p > 0.05 each). Furthermore, Cox regression analysis excluded an increased cardiovascular mortality in subjects with hyperuricemia.

Discussion

In contrast to the general population, hyperuricemia is not associated with increased mortality in patients undergoing hemodialysis. Moreover, xanthine oxidase inhibition was not associated with a survival benefit in this analysis. These data do not support the use of SUA lowering medication in hemodialysis patients with asymptomatic hyperuricemia.

Elevated serum uric acid and risk of cardiovascular or all-cause mortality in maintenance hemodialysis patients: A meta-analysis

BACKGROUND AND AIMS

Studies have shown inconsistent results about the association between serum uric acid (SUA) levels and mortality in hemodialysis patients. We performed this meta-analysis to determine whether higher SUA values comprised a risk factor of cardiovascular or all-cause mortality in maintenance hemodialysis patients.

METHODS AND RESULTS

Pubmed, Embase and the Cochrane library were searched up to August 31, 2020 for the longitudinal studies that investigated the association between the elevated SUA and cardiovascular or all-cause mortality risk in maintenance hemodialysis patients. Pooled adjusted hazard ratios (HR) and corresponding 95% confidence interval (CI) were calculated using a random-effects model. We included 10 studies with an overall sample of 264,571 patients with hemodialysis in this meta-analysis. Patients with the highest SUA were associated with a decreased risk of cardiovascular mortality (HR = 0.72, 95% CI 0.59-0.87) compared with patients with the lowest SUA after adjustment for potential confounders in a random effects model. Moreover, for each increase of 1 mg/dl of SUA, the overall risks of all-cause and cardiovascular mortality decreased by 6% and 9%, respectively (HR = 0.94, 95% CI 0.90-0.99; HR = 0.91, 95% CI 0.89-0.94).

CONCLUSION

Elevated SUA levels are strongly and independently associated with lower risk of cardiovascular mortality in maintenance hemodialysis patients. More designed studies, especially randomized controlled trials, should be conducted to determine whether high SUA levels is an independent risk factor of all-cause mortality in hemodialysis patients.

Hyperuricemia in Kidney Disease: A Major Risk Factor for Cardiovascular Events, Vascular Calcification, and Renal Damage

Kidney disease, especially when it is associated with a reduction in estimated glomerular filtration rate, can be associated with an increase in serum urate (uric acid), suggesting that hyperuricemia in subjects with kidney disease may be a strictly secondary phenomenon. Mendelian randomization studies that evaluate genetic scores regulating serum urate also generally have not found evidence that serum urate is a causal risk factor in chronic kidney disease. Nevertheless, this is countered by a large number of epidemiologic, experimental, and clinical studies that have suggested a potentially important role for uric acid in kidney disease and cardiovascular disease. Here, we review the topic in detail. Overall, the studies strongly suggest that hyperuricemia does have an important pathogenic role that likely is driven by intracellular urate levels. An exception may be the role of extracellular uric acid in atherosclerosis and vascular calcification. One of the more striking findings on reviewing the literature is that the primary benefit of lowering serum urate in subjects with CKD is not by slowing the progression of renal disease, but rather by reducing the incidence of cardiovascular events and mortality. We recommend large-scale clinical trials to determine if there is a benefit in lowering serum urate in hyperuricemic subjects in acute and chronic kidney disease and in the reduction of cardiovascular morbidity and mortality in subjects with end-stage chronic kidney disease.

Effect of uric acid levels on mortality in Japanese peritoneal dialysis patients

Background:

Unlike the situation in the general population, most studies of patients receiving hemodialysis have reported lower uric acid (UA) as associated with higher mortality. However, the relationship between UA level and mortality remains unclear among patients receiving peritoneal dialysis (PD).

Methods:

We collected baseline data for 4742 prevalent PD patients (age, 63 ± 14 years; male, 61.5%; diabetes, 29.1%; median dialysis duration, 28 months) from a nationwide dialysis registry in Japan at the end of 2012. One-year all-cause and cardiovascular (CV) mortality and mortality caused by infectious disease were assessed using Cox regression analysis and competing-risks regression analysis, respectively. We used multiple imputation to deal with missing covariate data.

Results:

Within 1 year, 379 patients (8.0%) died, including 129 patients (2.7%) from CV causes and 95 patients (2.0%) from infectious disease. In multivariate analysis, serum UA, treated as a continuous variable, was not associated with any outcome. Conversely, both lower (<297 µmol/L) and higher (≥476 µmol/L) UA levels were independently associated with higher all-cause mortality compared to the reference group (416 to <446 µmol/L) in analyses where serum UA was treated as a categorical variable. Body mass index (BMI) affected the association between serum UA and all-cause mortality (interaction p = 0.049).

Conclusions:

A U-shaped relationship appears to exist between UA levels and all-cause mortality among Japanese PD patients. Additionally, lower BMI significantly enhanced the effect of UA levels on mortality.

Association of Serum Uric Acid Concentration and Its Change with Cardiovascular Death and All-Cause Mortality

Objective

There is no consensus on the role of abnormal uric acid (UA) levels in the prognosis of patients undergoing hemodialysis. We therefore aimed to investigate the effects of changes in UA concentration on the risk of all-cause death and cardiac death in such patients.

Method

In this retrospective cohort study, patients admitted to two hemodialysis centers performing maintenance hemodialysis (MHD) in Wuhan First Hospital and Fourth Hospital Hemodialysis Center from January 1, 2007, to October 31, 2017, were included.

Results

In all, 325 patients undergoing MHD aged 59.7 ± 14.7 years, including 195 men (60%), were enrolled, with a median follow-up of 37 months. Serum UA (p < 0.001) was significantly higher in the surviving group than in the death group. No significant difference was found in UA variability (p < 0.001) was significantly higher in the surviving group than in the death group. No significant difference was found in UA variability (p < 0.001) was significantly higher in the surviving group than in the death group. No significant difference was found in UA variability (p < 0.001) was significantly higher in the surviving group than in the death group. No significant difference was found in UA variability (p < 0.001) was significantly higher in the surviving group than in the death group. No significant difference was found in UA variability (p < 0.001) was significantly higher in the surviving group than in the death group. No significant difference was found in UA variability (p < 0.001) was significantly higher in the surviving group than in the death group. No significant difference was found in UA variability (p < 0.001) was significantly higher in the surviving group than in the death group. No significant difference was found in UA variability (

Conclusion

Low UA levels were closely related to all-cause mortality in patients undergoing MHD. Although UA levels had no significant effect on cardiac death, they had a good predictive value for long-term prognosis in patients on MHD.