The dirty little secret of urate-lowering therapy: useless to stop chronic kidney disease progression and may increase mortality

Optimization of cardiovascular risk factor management in patients with BCR::ABL1 negative chronic myeloproliferative neoplasms, current knowledge, and perspectives

The exact prognostic role of cardiovascular (CV) risk factors in patients with BCR::ABL1 negative chronic myeloproliferative neoplasms (MPNs) remains unknown as it is often masked by other MPN-related features that bear strong prognostic impact on thrombotic risk. Therefore, current MPN treatment is not primarily guided by presence of CV risk factors. Treatment of CV risk factors in MPN patients usually mirrors that from the general population, despite the fact that CV risk factors in MPNs have their own specificities. Moreover, the optimal target levels for different metabolic deflections in MPNs (i.e., low-density lipoprotein, serum uric acid, or glycated hemoglobin levels) have not been defined. In the current review, we separately discuss the most important aspects of every individual CV risk factor (arterial hypertension, hyperlipidemia, chronic kidney disease, smoking, diabetes mellitus, hyperuricemia, and obesity and cachexia) in MPNs, summarize recent advances in the field, and propose future directions and research areas which may be needed to appropriately manage CV risk factors in MPNs.

Interaction between anemia and hyperuricemia in the risk of all-cause mortality in patients with chronic kidney disease

Aim

Both hyperuricemia and anemia are not only the manifestation of chronic kidney disease (CKD) but also related to its occurrence and development. A recent study has found that there was a synergetic effect between hyperuricemia and anemia on new-onset CKD. Herein we aimed to explore the roles of hyperuricemia and anemia in the all-cause mortality in patients with CKD.

Methods

Data of adult patients with CKD were extracted from the National Health and Nutrition Examination Surveys (NHANES) database in 2009-2018 in this retrospective cohort study. Weighted univariate and multivariate COX regression analyses were used to investigate the associations of hyperuricemia and anemia with all-cause mortality, and the evaluation indexes were hazard ratios (HRs) and 95% confidence intervals (CIs). The interaction effect between hyperuricemia and anemia on the risk of all-cause mortality was assessed via relative excess risk due to interaction (RERI) and attributable proportion of interaction (AP). Subgroup analyses of age, gender, CVD, hypertension, DM, and cancer were also performed to assess this interaction effect.

Results

Among 3,678 eligible patients, 819 died from all causes. After adjusting for covariables, we found that CKD patients with anemia (HR = 1.72, 95%CI: 1.42-2.09) or hyperuricemia (HR = 1.21, 95%CI: 1.01-11.45) had a higher risk of all-cause mortality. There was a potential synergetic effect between anemia and hyperuricemia on all-cause mortality, with RERI of 0.630 and AP of 0.291. Moreover, this synergetic effect was also observed in ≥65 years old (AP = 0.330), male (AP = 0.355), hypertension (AP = 0.736), non-hypertension (AP = 0.281), DM (AP = 0.371), and cancer (AP = 0.391) subgroups.

Conclusion

A potential synergetic effect between anemia and hyperuricemia on all-cause mortality was found in patients with CKD. However, further studies are needed to clarify the causal relationship between them.

Hyperuricaemia-associated all-cause mortality risk effect is increased by non-impaired kidney function - Is renal hyperuricaemia less dangerous?

BACKGROUND

Both hyperuricaemia and chronic kidney disease are known mortality risk factors. This study examined the modifying effect of renal function on hyperuricaemia-associated mortality risk, which is an issue that has not been studied before.

METHODS

Data on levels of serum uric acid (SUA), creatinine, cystatin C and other variables of persons aged 52-76 years were collected. Persons with SUA >410 μmol/L (75th percentile) were classified as clearly hyperuricaemic and persons with eGFR of ≤67 ml/min (25th percentile) as having reduced kidney function.

RESULTS

Reduced kidney function was associated with higher mortality in both SUA groups. When compared to individuals with SUA ≤410 μmol/L and eGFR >67 ml/min the hazard ratio (HR) for all-cause mortality was 1.53 (95 % CI: 1.26-1.84) in clearly hyperuricaemic persons with reduced kidney function, 1.26 (95 % CI: 1.02-1.55) in clearly hyperuricaemic persons with eGFR of >67 ml/min and 1.15 (95 % CI: 0.96-1.39) in persons with SUA ≤410 μmol/L and reduced kidney function. The HR for hyperuricaemia-related premature death was lowest in individuals with reduced eGFR, and it rose strikingly as the eGFR increased above 90 ml/min.

CONCLUSIONS

Reduced kidney function is a risk factor for mortality both in individuals with normal and elevated SUA. The hyperuricaemia-associated mortality risk is remarkably higher in individuals with normal kidney function than in individuals with reduced kidney function. Presumably overproduction of uric acid (metabolic hyperuricaemia) is a separate and more deleterious entity than hyperuricaemia resulting from reduced renal excretion of uric acid (renal hyperuricaemia).

Enzyme-functionalized hydrogel film for extracorporeal uric acid reduction

Enzyme replacement therapy for hyperuricemia treatment has been proven effective for critical state hyperuricemia patients. Still, direct administration of recombinant uricase can induce several fatal side effects. To circumvent this drawback, hydrogel protein carriers can be used in platforms for extracorporeal treatment such as microscale-based devices. In this work, calcium alginate and poly-(vinyl alcohol) hydrogel films were studied for their urate oxidase immobilization and uric acid reduction, which could be implemented in microscale-based extracorporeal devices. A mathematical model was developed in conjunction with uric acid reduction experiments to evaluate the influence of mass transfer and reaction parameters in the Michaelis-Menten kinetic expression. Alginate hydrogels prepared with crosslinker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-(hydroxysuccinimide) offered superior diffusivity of uric acid in the gel matrix at the maximum value ofD g , UA ≈ $$ {D}_{\mathrm{g},\mathrm{UA}}\approx $$ 1.98 × 10-11  m2 /s compared with alginate prepared solely from ionic crosslinking withD g , UA ≈ $$ {D}_{\mathrm{g},\mathrm{UA}}\approx $$  5.31 × 10-12  m2 /s at the same alginate concentration. The maximum value of νmax was experimentally determined at 7.78 × 10-5  mol/(m3 s). A 3% sodium alginate hydrogel with crosslinkers yielded the highest reduction of uric acid at 92.70%. The mathematical model demonstrated an excellent prediction of uric acid conversion suggesting potential use of the model for formulation and maximizing the therapeutic performance of functionalized hydrogels.

Gout and hyperuricaemia: modifiable cardiovascular risk factors?

Gout and hyperuricaemia are two clinical situations associated with an elevated risk of developing cardiovascular (heart failure, myocardial infarction, stroke) and metabolic and renal complications. One reason is probably related to the fact that the prevalence of hyperuricaemia and gout is high in clinical situations, which themselves involve a high cardiovascular risk, such as hypertension, diabetes, chronic kidney disease or obesity. However, recent studies suggest that hyperuricaemia may promote cardiovascular complications independently of other cardiovascular risk factors, by inducing chronic inflammation, oxidative stress, and endothelial dysfunction. The questions that arise today concern primarily the treatment of asymptomatic hyperuricaemia. Should it be treated to decrease the patients' cardiovascular risk and if so, starting from which level and towards which target? There are now several pieces of evidence indicating that this might be useful, but data from large studies are not unanimous. This review will discuss this issue as well as new well-tolerated treatments, such as febuxostat or SGLT2 inhibitors, which lower uric acid levels, prevent gout and lower the risk of cardio-renal events.

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.

Hyperuricemia and Progression of Chronic Kidney Disease: A Review from Physiology and Pathogenesis to the Role of Urate-Lowering Therapy

The relationship between hyperuricemia, gout, and renal disease has been investigated for several years. From the beginning, kidney disease has been considered a complication of gout; however, the viewpoints changed, claiming that hypertension and elevated uric acid (UA) levels are caused by decreased urate excretion in patients with renal impairment. To date, several examples of evidence support the role of hyperuricemia in cardiovascular or renal diseases. Several mechanisms have been identified that explain the relationship between hyperuricemia and chronic kidney disease, including the crystal effect, renin-angiotensin-aldosterone system activation, nitric oxide synthesis inhibition, and intracellular oxidative stress stimulation, and urate-lowering therapy (ULT) has been proven to reduce renal disease progression in the past few years. In this comprehensive review, the source and physiology of UA are introduced, and the mechanisms that explain the reciprocal relationship between hyperuricemia and kidney disease are reviewed. Lastly, current evidence supporting the use of ULT to postpone renal disease progression in patients with hyperuricemia and gout are summarized.

Dietary and Lifestyle-Centered Approach in Gout Care and Prevention

PURPOSE OF REVIEW

We aim to provide a comprehensive review of the available literature to inform dietary recommendations for patients with gout and hyperuricemia that have the potential to simultaneously lower serum urate and reduce gout morbidity while addressing gout's cardiometabolic comorbidities holistically.

RECENT FINDINGS

The global burden of gout is rising worldwide, particularly in developed nations as well as in women. Patients with gout are often recommended to follow a low-purine (i.e., low-protein) diet to avoid purine-loading. However, such an approach may lead to increased consumption of unhealthy carbohydrates and fats, which in turn contributes to metabolic syndrome and subsequently raises serum urate levels and leads to adverse cardiovascular outcomes. On the other hand, several well-established diets for cardiometabolic health, such as the Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diets, in combination with weight loss for those who are overweight or obese, also have beneficial effects on relevant gout endpoints. It is important to recognize not only the direct effect of diet on hyperuricemia and gout, but its mediated effect through obesity and insulin resistance. Thus, several preeminent healthy dietary patterns that have proven benefits in cardiometabolic health have the power to holistically address not only gout morbidity but also its associated comorbidities that lead to premature mortality among patients with gout.

Targeting the Pathobiology of Diabetic Kidney Disease

The pathobiology of diabetic kidney disease (DKD) involves an interplay between all the many different cell types that exist within the kidney and their shared and cumulative dysfunction in response to chronic hyperglycemia. DKD is characteriszed by morphological changes including tubular hypertrophy, podocyte dysfunction, mesangial expansion and mesangiolysis, endothelitis and capillary rarefaction, arteriolar hyalinosis, basement membrane thickening, and ultimately nephron dropout and tubulointerstitial fibrosis. These adaptive but ultimately maladaptive changes accelerate the progression of lesions in the diabetic kidney by increasing mechanical and oxidative stress, hypoxia, fibrogenesis, inflammation, senescence, and apoptosis. In particular, atrophy at the critical junction between Bowman's capsule and the proximal tubule likely represent the leading cause of nephron dropout and kidney function decline in DKD. Preventing, slowing, or reversing these changes should be the target of future "smart" therapies for patients with DKD, many of which are now under development.

Serum uric acid control for prevention of gout flare in patients with asymptomatic hyperuricaemia: a retrospective cohort study of health insurance claims and medical check-up data in Japan

Objectives

In patients with gout, treating to target serum uric acid levels (sUA) of ≤6.0 mg/dL is universally recommended to prevent gout flare. However, there is no consensus on asymptomatic hyperuricaemia. Using Japanese health insurance claims data, we explored potential benefits of sUA control for preventing gout flare in subjects with asymptomatic hyperuricaemia.

Methods

This retrospective cohort study analysed the JMDC Claims Database from April 2012 through June 2019. Subjects with sUA ≥8.0 mg/dL were identified, and disease status (prescriptions for urate-lowering therapy (ULT), occurrence of gout flare, sUA) was investigated for 1 year. Time to first onset and incidence rate of gout flare were determined by disease status subgroups for 2 years or more. The relationship between gout flare and sUA control was assessed using multivariable analysis.

Results

The analysis population was 19 261 subjects who met eligibility criteria. We found fewer occurrences of gout flare, for both gout and asymptomatic hyperuricaemia, in patients who achieved sUA ≤6.0 mg/dL with ULT than in patients whose sUA remained >6.0 mg/dL or who were not receiving ULT. In particular, analysis by a Cox proportional-hazard model for time to first gout flare indicated that the HR was lowest, at 0.45 (95% CI 0.27 to 0.76), in subjects with asymptomatic hyperuricaemia on ULT (5.0<sUA ≤ 6.0 mg/dL), compared with untreated subjects (sUA ≥8.0 mg/dL).

Conclusions

Occurrences of gout flare were reduced by controlling sUA at ≤6.0 mg/dL in subjects with asymptomatic hyperuricaemia as well as in those with gout.

Trial registration number

UMIN000039985.