Unclosing Premature Mortality Gap Among Patients With Gout in the US General Population, Independent of Serum Urate and Atherosclerotic Cardiovascular Risk Factors

OBJECTIVE

Gout flares are followed by transient major cardiovascular (CV) risk, implicating the role of inflammation; the aim of this study was to determine whether premature mortality rates in patients with gout and CV risk are independent of serum urate (SU) and atherosclerotic CV disease (ASCVD) risk factors.

METHODS

Using serial US nationwide prospective cohorts, we evaluated the independent association of prevalent gout with all-cause and CV mortality, adjusting for SU, ASCVD risk factors, comorbidities, medications, and kidney function and compared mortality rates between the early (1988-1994 baseline) and late cohorts (2007-2016 baseline). We replicated late cohort findings among patients with gout in a nationwide UK cohort (2006-2010 baseline).

RESULTS

Adjusted hazard ratios (HRs) for mortality rates in patients with prevalent gout were similar in early and late US cohorts (1.20 [1.03-1.40] and 1.19 [1.04-1.37], respectively); HRs with further adjustment for SU were 1.19 (1.02-1.38) and 1.19 (1.03-1.37), respectively. Adjusted HR among patients with gout from the UK late cohort was 1.61 (1.47-1.75); these associations were larger among women (P = 0.04) and prominent among Black individuals. Adjusted HR for CV mortality rates in the late US cohort was 1.39 (1.09-1.78); those for circulatory, CV, and coronary heart disease deaths among UK patients with incident gout were 1.48 (1.24-1.76), 1.49 (1.20-1.85), and 1.59 (1.26-1.99), respectively.

CONCLUSIONS

Patients with gout experience a persistent mortality gap in all-cause and CV deaths, even adjusting for SU and ASCVD risk factors, supporting a role for gout-specific pathways (eg, flare inflammation). These findings suggest gaps in current care, particularly in women and possibly among Black patients.

Multifaceted role of inosine in complex diseases and human health

Purines are chemical compounds integral to health and are crucial for the synthesis of nucleic acids. They are part of DNA and RNA and participate in various metabolic and signaling processes. They also function as neurotransmitters and serve as co-substrates for activating many metabolites. Inosine, a purine nucleoside, is a breakdown product of adenosine with similar properties and a much longer half-life (15 h vs ∼5 s) than adenosine. The purpose of this narrative review is to discuss the metabolic effects of inosine and highlight its beneficial properties and implication in complex diseases such as obesity, type 2 diabetes, cancers, cardiovascular diseases, and neurodegenerative diseases. A search was performed for purine- and inosine-related articles on the University of North Carolina (UNC) Health Sciences Library, PubMed, and Google Scholar sites. Inosine is involved in the regulation of RNA editing, metabolic enzyme activity, and signaling pathways. Animal and cell culture studies have shown inosine to be anti-inflammatory, immunomodulatory, and neuroprotective, and serving as a critical regulator of immune checkpoint inhibition therapeutic response in various tumor types. Recent studies have also implicated inosine in increasing energy expenditure, browning of adipose tissue, and improving leptin sensitivity. Human studies, however, have been limited to urate-elevating properties of inosine. These findings make inosine relevant to many complex diseases, and need to be translated to humans. Future studies should be conducted to investigate the mechanisms underlying the role of inosine in adiposity, inflammation, oxidative stress, and neuronal function.

The COMPARE head-to-head, randomized controlled trial of SEL-212 (pegadricase plus rapamycin-containing nanoparticle, ImmTOR™) versus pegloticase for refractory gout

OBJECTIVES

Serum urate (SU) lowering with PEGylated uricases in gout can reduce flares and tophi. However, treatment-emergent anti-drug antibodies adversely affect safety and efficacy and the currently approved PEGylated uricase pegloticase requires twice-monthly infusions. Investigational SEL-212 therapy aims to promote uricase-specific tolerance via monthly sequential infusions of a proprietary rapamycin-containing nanoparticle (ImmTOR) and pegadricase.

METHODS

COMPARE was a randomized, phase 2, open-label trial of SEL-212 vs pegloticase in adults with refractory gout. SEL-212 [ImmTOR (0.15 mg/kg) and pegadricase (0.2 mg/kg)] was infused monthly or pegloticase (8 mg) twice monthly for 6 months. The primary endpoint was the proportion of participants with SU <6 mg/dl for ≥80% of the time during 3 and 6 months. Secondary outcomes were mean SU, gout flares, number of tender and/or swollen joints and safety.

RESULTS

During months 3 and 6 combined, numerically more participants achieved and maintained a SU <6 mg/dl for ≥80% of the time with SEL-212 vs pegloticase (53.0% vs 46.0%, P = 0.181). The percentage reductions in SU levels were statistically greater during months 3 and 6 with SEL-212 vs pegloticase (-73.79% and -47.96%, P = 0.0161). Reductions in gout flare incidence and number of tender and/or swollen joints were comparable between treatments. There were numerical differences between the most common treatment-related adverse events of interest with SEL-212 and pegloticase: gout flares (60.2% vs 50.6%), infections (25.3% vs 18.4%) and infusion-related reactions (15.7% vs 11.5%), respectively. Stomatitis (and related terms) was experienced by eight participants (9.6%) with SEL-212 and none with pegloticase. Stomatitis, a known event for rapamycin, was associated with ImmTOR only.

CONCLUSIONS

SEL-212 efficacy and tolerability were comparable to pegloticase in refractory gout. This was associated with a substantial reduction in treatment burden with SEL-212 due to decreased infusion frequency vs pegloticase.

CLINICAL TRIAL REGISTRATION

NCT03905512.

Health literacy and gout characteristics in a primary care cohort

Objectives

To examine the cross-sectional association between health literacy and gout characteristics.

Methods

In a primary care cohort of adults living with gout, the prevalence of poor health literacy was defined using the Single-Item Literacy Screener (SILS). Multiple logistic regression was used to obtain adjusted odds ratios (ORs) for the cross-sectional associations between health literacy and individual gout characteristics (frequency of flares, age at gout onset, history of oligo-/polyarticular flares, allopurinol use, allopurinol dose and serum urate level) with 95% CIs and adjustment for age, sex, deprivation and further education.

Results

Of 551 participants [mean age 54.4 years (s.d. 11.2), 498 (90.4%) male], 163 (30.1%) reported two or more flares in the previous 12 months. Fifty-one (9.4%) had poor health literacy. Poor health literacy was associated with having two or more flares in the preceding 12 months [adjusted OR 4.10 (95% CI 2.04, 8.19)] and a history of oligo-/polyarticular flares [OR 1.93 (95% CI 1.06, 3.55)]. No associations were identified between health literacy and age at gout onset [OR 0.99 (95% CI 0.96, 1.01)], allopurinol use [OR 0.88 (95% CI 0.46, 1.65)] or dose [OR 1.00 OR (95% CI 1.00, 1.00)] or serum urate [most recent serum urate OR 1.0 (95% CI 1.00, 1.00)].

Conclusions

Frequent flares and a history of oligo-/polyarticular flares were associated with poor health literacy. Since health literacy is an important determinant of health outcomes, it is important to consider health literacy when providing information and education to people with gout.

The non-causative role of abnormal serum uric acid in intervertebral disc degeneration: A Mendelian randomization study

Background

Intervertebral disc degeneration (IDD) is a common musculoskeletal disorder that contributes significantly to disability and healthcare costs. Serum urate concentration has been implicated in the development of various musculoskeletal conditions. While previous observational studies have suggested an association between the two conditions, it might confound the effect of serum urate concentrations on IDD. This Mendelian randomization (MR) study aimed to investigate the causal relationship between serum urate concentration and IDD.

Methods

We performed a two-sample MR analysis using summary-level data from genome-wide association studies (GWAS) of serum urate concentration (n = 13 585 994 European ancestry) and IDD (n = 16 380 337 European ancestry). Single nucleotide polymorphisms (SNPs) significantly associated with serum urate concentration (p < 5 × 10-8) were selected as instrumental variables. The associations between genetically predicted serum urate concentration and IDD were estimated using the inverse-variance weighted (IVW) method, with sensitivity analyses employing the weighted median, MR-Egger, and MR-PRESSO approaches to assess the robustness of the findings.

Results

In the primary IVW analysis, genetically predicted serum urate concentration was unrelated associated with IDD (odds ratio [OR] = 1.00, 95% confidence interval (CI): 1.00-1.00, p = 0.17)). The results remained consistent across the sensitivity analyses, and no significant directional pleiotropy was detected (MR-Egger intercept: p = 0.15).

Conclusions

This MR study provides evidence that there is no causal relationship between serum urate concentration and IDD. It suggests previous observational associations may be confounded. Serum urate levels are unlikely to be an important contributor to IDD.

Are patients with gout with negative dual-energy computed tomography for monosodium urate crystal deposition easy-to-treat?

OBJECTIVES

To determine the clinical associations and predictive value of two thresholds of negative dual-energy CT (DECT) for MSU crystal deposition in gout patients initiating urate lowering therapy (ULT), and identify which threshold is more clinically relevant.

METHODS

Patients from the CRYSTALILLE cohort with a diagnosis of gout naive to ULT with baseline DECT scans of knees and feet were selected. Two thresholds of positivity for DECT detection of MSU crystal deposition were considered (<0.01 cm3 and <0.1 cm3). Baseline characteristics and the prediction of key outcomes after ULT initiation including reaching serum urate (SU) levels <6.0 and 5.0 mg/dl and occurrence of flares at 6, 12 and 24 months, associated with both thresholds of negative DECTs were compared with those of.

PATIENT

s having positive DECT scans.

RESULTS

211 patients aged 66.2 years [57; 75.8] with a symptom duration of 3 years [0; 7.8] were included. 38/211 (18%) and 90/211 (43%) had negative DECT scans for the 0.01 and 0.1 cm3 thresholds, respectively. Factors associated with negative DECT scans were younger age, shorter symptom duration, and absence of cardiovascular disease for both volume thresholds. 9/39 (23.1%), 3/26 (11.5%), and 1/18 (5.6%) of patients with <0.1 cm3 MSU crystals had flares at 6, 12 and 24 months, respectively, compared with 18/45 (40.0%), 9/36 (25.0%) and 2/18 (11.1%) patients with ≥0.1 cm3 (p> 0.05).Overall, 95 patients (68.3%) reached SU levels <6.0 mg/dl and 68 (48.9%) <5.0 mg/dl, without any difference between positive and negative DECTs, with ULT dosages which tended to be lower in patients with negative DECT.

CONCLUSION

The 0.1 cm3 threshold was better correlated to clinical presentation and evolution than 0.01 cm3. Patients with gout with negative DECTs exhibit milder disease and a lower comorbidity burden. They do not exhibit particularly easy-to-treat hyperuricemia, but may have a lower risk of flares.

Incidence density of hyperuricemia and association between metabolism-related predisposing risk factors and serum urate in Chinese adults: a cohort study

Background

Evidence regarding the association between metabolism-related indicators and serum urate (SU) is limited. We aimed to obtain the incidence density of hyperuricemia and to explore the association between metabolism-related predisposing risk factors and SU.

Methods

A total of 48,979 Chinese adults from the Beijing Physical Examination Center were included in the study. The partial least squares path model was used to explore the relationship between SU and metabolism-related risk factors. The generalized additive model was used for smooth curve fitting, showing the sex-specific associations of SU at follow-up with baseline fasting blood glucose (FBG) concentrations and age.

Results

The incidence density of hyperuricemia was 78/1000 person-years. Baseline SU, age, sex, obesity, FBG, and lipid metabolism were significantly associated with SU at follow-up (all P values <0.05). Non-linear relationships were found between the baseline FBG concentrations and SU at follow-up, while U-shaped associations were observed between baseline age and SU at follow-up.

Conclusions

The SU concentration is associated with several metabolism-related risk factors such as obesity and FBG. Recognition of these associations will aid in a deeper understanding of the multifaceted nature of SU regulation.

Patient factors and health outcomes associated with illness perceptions in people with gout

OBJECTIVE

Illness perceptions are views and beliefs formed in response to a health threat which may influence self-management behaviours and chronic disease outcomes. Despite effective medication, sub-optimal outcomes in gout are common. This study aimed to quantitatively investigate illness perceptions in gout to examine how illness perceptions relate to health outcomes.

METHODS

Data were obtained from a randomised-controlled trial where people with gout (n = 493) completed surveys measuring illness perceptions (Brief Illness Perception Questionnaire (B-IPQ)), gout flares, medication adherence, health-related quality of life, healthcare utilisation and productivity, alongside serum urate blood tests at baseline, 6- and 12-month follow-ups. Multivariable linear regression identified patient factors independently associated with each B-IPQ item score. Logistic and linear regression, adjusted for age and sex, determined whether baseline B-IPQ items could predict current and future health outcomes.

RESULTS

Younger individuals and those with severe gout were more likely to experience pessimistic illness perceptions at baseline. Optimistic illness perceptions were associated with lower odds of having at least one flare in the preceding 6 months. Every 1-point increase in B-IPQ treatment control, indicating the optimistic view that gout is treatable, decreased the odds of a recent flare prior to baseline by 33% (OR : 0.67; 95%CI : 0.53,0.85; p< 0.001) and prior to 12-month follow-up by 15% (OR : 0.85; 95%CI : 0.76,0.96; p= 0.01). Pessimistic illness perceptions also predicted poorer medication adherence, health-related quality of life and productivity but not serum urate levels.

CONCLUSION

Modifying pessimistic illness perceptions, including, but not limited to, patient education, may promote prudent self-management behaviours and better outcomes in gout.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry; https://www.anzctr.org.au/; ACTRN12616000455460.

Serum Urate Levels and Ultrasound Characteristics of Carotid Atherosclerosis across Obesity Phenotypes

BACKGROUND

Existing evidence suggests a close link among high levels of serum urate (SU), obesity and carotid atherosclerosis. The aim of the present study was to evaluate the interrelations between SU levels and carotid atherosclerosis in subjects with different obesity phenotypes.

METHODS

In this study, a total of 2076 subjects (mean age 48.1 ± 13.1 years; 1307 women) were recruited: 59 with general obesity, 616 with central obesity, 715 with mixed (general-central) obesity and 686 non-obese. Anthropometric measurements, vascular risk factors, blood biochemistry analysis (including SU levels), and carotid ultrasound were performed. Ultrasound assessment included evaluation of intima-media thickness (IMT) and plaque characteristics, including number, total area and type (vulnerable vs. stable) of plaques.

RESULTS

After adjustment for potential confounders, the highest levels of SU were observed in subjects with mixed obesity, followed by subjects with central obesity, general obesity and the non-obese (309.4 ± 82.2 vs. 301.2 ± 73.1 vs. 272.9 ± 61.8 vs. 234.2 ± 59.8 μmol/L, respectively; F = 149.2, post hoc p < 0.001). Similarly, subjects with mixed and central obesity presented higher values of IMT compared to subjects with general obesity and the non-obese (0.68 ± 0.16 vs. 0.67 ± 0.16 vs. 0.62 ± 0.14 vs. 0.57 ± 0.13 mm, respectively; F = 54.2, post hoc p < 0.001). No difference in number, total area and type of plaques among obesity groups were attested (all p > 0.05). Significantly higher IMT values were observed in subjects with increased SU levels compared to subjects with normal SU levels (0.70 ± 0.10 vs. 0.62 ± 0.14 mm, p = 0.02) only within the central obesity group. Increasing levels of SU were associated with a higher frequency of increased IMT only in subjects with central obesity (OR 1.033, 95% CI 1.025-1.041). Similarly, SU levels yielded a satisfactory performance in detecting subjects with increased IMT (AUC 0.65, 95% CI 0.50-0.73, subjects with carotid plaques (0.62, 95% CI 0.55-0.68) and subjects with vulnerable plaque types (0.68, 0.59-0.76) only within the central obesity group.

CONCLUSIONS

Among the studied obesity types, the association between SU levels and markers of carotid atherosclerosis was of particular significance in subjects with central obesity.

Investigating a possible causal relationship between maternal serum urate concentrations and offspring birthweight: a Mendelian randomization study

BACKGROUND

Higher urate levels are associated with higher systolic blood pressure (SBP) in adults, and in pregnancy with lower offspring birthweight. Mendelian randomization (MR) analyses suggest a causal effect of higher urate on higher SBP and of higher maternal SBP on lower offspring birthweight. If urate causally reduces birthweight, it might confound the effect of SBP on birthweight. We therefore tested for a causal effect of maternal urate on offspring birthweight.

METHODS

We tested the association between maternal urate levels and offspring birthweight using multivariable linear regression in the Exeter Family Study of Childhood Health (EFSOCH; n = 872) and UK Biobank (UKB; n = 133 187). We conducted two-sample MR to test for a causal effect of maternal urate [114 single-nucleotide polymorphisms (SNPs); n = 288 649 European ancestry] on offspring birthweight (n = 406 063 European ancestry; maternal SNP effect estimates adjusted for fetal effects). We assessed a causal relationship between urate and SBP using one-sample MR in UKB women (n = 199 768).

RESULTS

Higher maternal urate was associated with lower offspring birthweight with similar confounder-adjusted magnitudes in EFSOCH [22 g lower birthweight per 1-SD higher urate (95% CI: -50, 6); P = 0.13] and UKB [-28 g (95% CI: -31, -25); P = 1.8 × 10-75]. The MR causal effect estimate was directionally consistent, but smaller [-11 g (95% CI: -25, 3); PIVW = 0.11]. In women, higher urate was causally associated with higher SBP [1.7 mmHg higher SBP per 1-SD higher urate (95% CI: 1.4, 2.1); P = 7.8 × 10-22], consistent with that previously published in women and men.

CONCLUSION

The marked attenuation of the MR result of maternal urate on offspring birthweight compared with the multivariable regression result suggests previous observational associations may be confounded. The 95% CIs of the MR result included the null but suggest a possible small effect on birthweight. Maternal urate levels are unlikely to be an important contributor to offspring birthweight.

Initiation Dose of Allopurinol and the Risk of Severe Cutaneous Reactions in Older Adults With CKD: A Population-Based Cohort Study

RATIONALE & OBJECTIVE

Allopurinol should be started at lower doses in patients with chronic kidney disease (CKD) to avoid adverse effects. We examined the risk of severe cutaneous reactions in older adults with CKD who were newly prescribed allopurinol at varied doses.

STUDY DESIGN

Population-based cohort study using linked health care databases.

SETTING & PARTICIPANTS

Patients in Ontario, Canada (2008-2019) aged ≥66 years, with an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m², and who were new users of allopurinol.

EXPOSURE

A new prescription for allopurinol >100 mg/d versus a dose ≤100 mg/d.

OUTCOME

The primary outcome was a hospital visit with a severe cutaneous reaction within 180 days of starting allopurinol. Secondary outcomes included all-cause hospitalization and all-cause mortality.

ANALYTICAL APPROACH

The exposure and referent groups were balanced on indicators of baseline health using inverse probability of treatment weighting on the propensity score. Weighted risk ratios (RR) were obtained using modified Poisson regression and weighted risk differences (RD) using binomial regression.

RESULTS

Of 47,315 patients (median age, 76 years; median eGFR, 45 mL/min/1.73 m²), 55% started allopurinol at >100 mg/d. Starting allopurinol at >100 versus ≤100 mg/d was associated with an increased risk of a severe cutaneous reaction: number of events (weighted), 103 of 25,802 (0.40%) versus 46 of 25,816 (0.18%), respectively (weighted RR, 2.25 [95% CI, 1.50-3.37]; weighted RD, 0.22% [95% CI, 0.12%-0.32%]. Starting allopurinol at >100 versus ≤100 mg/d was associated with an increased risk of all-cause hospitalization but not with all-cause mortality.

LIMITATIONS

This study was underpowered to detect risk differences in the association of allopurinol dose with outcomes across eGFR categories (ie, 45-59, 30-44, and <30 mL/min/1.73 m²).

CONCLUSIONS

Older patients with CKD who started allopurinol at >100 mg/d versus ≤100 mg/d were twice as likely to visit a hospital with a severe cutaneous reaction in the next 180 days.

Local genetic covariance between serum urate and kidney function estimated with Bayesian multitrait models

Hyperuricemia (serum urate &gt;6.8 mg/dl) is associated with several cardiometabolic and renal diseases, such as gout and chronic kidney disease. Previous studies have examined the shared genetic basis of chronic kidney disease and hyperuricemia in humans either using single-variant tests or estimating whole-genome genetic correlations between the traits. Individual variants typically explain a small fraction of the genetic correlation between traits, thus the ability to map pleiotropic loci is lacking power for available sample sizes. Alternatively, whole-genome estimates of genetic correlation indicate a moderate correlation between these traits. While useful to explain the comorbidity of these traits, whole-genome genetic correlation estimates do not shed light on what regions may be implicated in the shared genetic basis of traits. Therefore, to fill the gap between these two approaches, we used local Bayesian multitrait models to estimate the genetic covariance between a marker for chronic kidney disease (estimated glomerular filtration rate) and serum urate in specific genomic regions. We identified 134 overlapping linkage disequilibrium windows with statistically significant covariance estimates, 49 of which had positive directionalities, and 85 negative directionalities, the latter being consistent with that of the overall genetic covariance. The 134 significant windows condensed to 64 genetically distinct shared loci which validate 17 previously identified shared loci with consistent directionality and revealed 22 novel pleiotropic genes. Finally, to examine potential biological mechanisms for these shared loci, we have identified a subset of the genomic windows that are associated with gene expression using colocalization analyses. The regions identified by our local Bayesian multitrait model approach may help explain the association between chronic kidney disease and hyperuricemia.

Effect of sodium-glucose cotransporter-2 (SGLT2) inhibitors on serum urate levels in patients with and without diabetes: a systematic review and meta-regression of 43 randomized controlled trials

Objectives

Sodium-glucose cotransporter-2 (SGLT2) inhibitors have been found to reduce serum urate in patients with type 2 diabetes mellitus. To evaluate if this effect applies to both patients with and without diabetes, we conducted a systematic review and meta-analysis of SGLT2 inhibitors on serum urate levels in this population.

Methods

Four electronic databases (PubMed, Embase, Cochrane and SCOPUS) were searched on 25 September 2021 for articles published from 1 January 2000 up to 25 September 2021, for studies that examined the effect of SGLT2 inhibitors on serum urate in study subjects. Random-effects meta-analysis was performed, with subgroup analyses on the type of SGLT2 inhibitor agent administered, presence of type 2 diabetes mellitus, presence of chronic kidney disease and drug dose.

Results

A total of 43 randomized controlled trials, with a combined cohort of 31,921 patients, were included. Both patients with [-31.48 μmol/L; 95% confidence interval (CI): -37.35 to -25.60] and without diabetes (-91.38 μmol/L; 95% CI: -126.53 to -56.24) on SGLT2 inhibitors had significantly lower urate levels when compared with placebo. This treatment effect was similarly observed across different types of SGLT2 inhibitors. However, in type 2 diabetes mellitus (T2DM) patients with chronic kidney disease, the reduction in serum urate with SGLT2 inhibitors became insignificant (95% CI: -22.17 to 5.94, p < 0.01).

Conclusion

This study demonstrated that SGLT2 inhibitors are beneficial in reducing serum urate in patients with and without diabetes. SGLT2 inhibitors could therefore contribute to the general treatment of hyperuricaemia.

Associations between serum urate and telomere length and inflammation markers: Evidence from UK Biobank cohort

Objective

Hyperuricemia and gout have become gradually more common. The effect of serum urate on organism aging and systematic inflammation is not determined. This study aims to evaluate whether serum urate is causally associated with cellular aging markers and serum inflammation markers.

Methods

A Mendelian randomization study was performed on summary-level data from the largest published genome-wide association studies. Single nucleotide polymorphisms with a genome-wide significance level were selected as instrumental variables for leukocyte telomere length (LTL), and serum soluble makers of inflammation (CRP, IL-6, TNF-α, and IGF-1). Standard inverse variance weighted (IVW) method was used as the primary statistical method. The weighted median, MR-Egger regression, and MR-PRESSO methods were used for sensitivity analysis.

Results

An inverse causal association of genetically predicted serum urate levels and LTL was found using IVW method (OR: 0.96, 95%CI 0.95, 0.97; β=-0.040; SE=0.0072; P=4.37×10^-8). The association was also supported by MR results using MR-Egger method and weighted median method. The MR-PRESSO analysis and leave-one-out sensitivity analysis supported the robustness of the combined results. In terms of other aging-related serum biomarkers, there was no evidence supporting a causal effect of serum urate on CRP, IL-6, TNF-α, or IGF-1 levels.

Conclusions

Serum urate levels are negatively associated with telomere length but are not associated with serum soluble indicators of inflammation. Telomere length may be a critical marker that reflects urate-related organismal aging and may be a mechanism in the age-related pathologies and mortality caused by hyperuricemia.

Efficacy and safety of switching from febuxostat to dotinurad, a novel selective urate reabsorption inhibitor, in hyperuricemic patients with type 2 diabetic kidney disease: Protocol for a single-arm, open-label, prospective, exploratory study

BACKGROUND

Dotinurad is a novel uricosuric drug in Japan with selective and potent urate transporter 1 (URAT1) inhibitory activity. This study aims to evaluate the efficacy and safety of dotinurad in hyperuricemic patients with type 2 diabetic kidney disease by comparing serum levels of urate and plasma and urinary levels of indoxyl sulfate excreted via the urate excretion transporter ATP binding cassette subfamily G member 2 (ABCG2), as indices, with baseline levels after switching from febuxostat to dotinurad.

METHODS

This single-center, single-arm, open-label, prospective, exploratory study aims to evaluate the effect of switching from febuxostat to dotinurad on serum urate levels and its background factors. The study will include 50 hyperuricemic patients with type 2 diabetic kidney disease and urate levels exceeding 6 mg/dL despite administration of febuxostat 20 mg/day for at least 3 months. The primary outcome is the achievement rate of serum urate levels of ≤6 mg/dL after 24 weeks of treatment with dotinurad at 0.5 mg to a maximum of 4 mg once daily. Secondary outcomes include the changes in serum urate levels, plasma and urinary indoxyl sulfate levels, and renal injury-related markers from baseline to observation points at weeks 4, 12, and 24.

DISCUSSION

The study hypothesizes that switching to dotinurad may reduce the plasma levels of indoxyl sulfate and increase its urinary levels in patients with hyperuricemia. These suggest that dotinurad can potently lower the serum urate level by inhibiting URAT1 without adversely affecting ABCG2. Thus, findings of this study are expected to provide useful insights into the treatment of hyperuricemia associated with type 2 diabetic kidney disease and the discovery of new possibilities for dotinurad.

ETHICS AND DISSEMINATION

Prior to the study, its study protocol was scientifically and ethically reviewed and approved by the Japan Physicians Association Clinical Research Review Board (approval number: JPA007-2204-02). In addition, patients who provide written informed consent will participate in the study. The results of this study will be published through submission to a peer-reviewed scientific journal.

CLINICAL TRIAL REGISTRATION

https://jrct.niph.go.jp/en-latest-detail/jRCTs031220080, identifier jRCTs031220080.

The role of lipid traits in mediating the effect of body mass index on serum urate

OBJECTIVE

To explore whether total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglyceride (TG) are mediators in the pathway of body mass index (BMI) on serum urate and determine the proportion of the mediation effect.

METHODS

This study used observational and two-sample Mendelian randomization (MR) analyses to explore the mediation effects of TC, HDL, LDL, and TG in the pathway of BMI on serum urate. We determined the size and the extent to which these lipids mediate any effect of BMI on serum urate.

RESULTS

Observational analysis results showed that HDL and TG can partially explain the association of BMI on serum urate, and the proportion of mediation effect was 10.2% and 8.9%, respectively. MR results demonstrated that TG has a causal effect on serum urate (β = 0.22, 95% CI: 0.15, 0.29; p = 2.28×10^-10.) and its proportion of mediation effect was 14.1%. TC, HDL, and LDL are not the mediators in the pathway of BMI on serum urate in MR estimates.

CONCLUSION

To a certain extent, TG mediates the effect of BMI on serum urate, and the risk of gout may be reduced by controlling both BMI and TG.

Effects of a Behavioral Weight Loss Intervention and Metformin Treatment on Serum Urate: Results from a Randomized Clinical Trial

Background: Lower body mass index (BMI) has been associated with lower serum urate (SU), but only in observational studies. We sought to determine the effects of behavioral weight loss and metformin treatment on SU in a randomized trial. Methods and Findings: The Survivorship Promotion In Reducing IGF-1 Trial (SPIRIT) was a parallel three-arm randomized controlled trial of overweight/obese adult cancer survivors without gout at a single center in Maryland, United States. Participants were randomized to: (1) coach-directed weight loss (behavioral telephonic coaching), (2) metformin (up to 2000 mg daily), or (3) self-directed weight loss (informational brochures; reference group). SU and BMI were assessed at baseline and at 3, 6, and 12 months post-randomization. The 121 participants had a mean ± standard deviation (SD) age of 60 ± 9 years, 79% were female, and 45% were Black. At baseline, BMI was 35 ± 5 kg/m², and SU was 5.6 ± 1.3 mg/dL. Compared to the self-directed group, at 12 months, the coach-directed group reduced BMI by 0.9 kg/m² (95% confidence interval (CI): -1.5, -0.4) and metformin reduced BMI by 0.6 kg/m² (95% CI: -1.1, -0.1). However, compared to the self-directed group, the coach-directed group unexpectedly increased SU by 0.3 mg/dL (95% CI: 0.05, 0.6), and metformin non-significantly increased SU by 0.2 mg/dL (95% CI: -0.04, 0.5); these effects were attenuated when analyses included change in estimated glomerular filtration rate (eGFR). Conclusions: In this randomized trial of cancer survivors without gout, reductions in BMI either increased or did not change SU, potentially due to effects on eGFR. These results do not support a focus on BMI reduction for SU reduction; however, long-term studies are needed. ClinicalTrials.gov Registration: NCT02431676.

The efficacy and tolerability of febuxostat treatment in a cohort of Chinese Han population with history of gout

Objective

To measure the effect of febuxostat on the serum levels of uric acid (sUA) and the proinflammatory cytokines interleukin (IL)-6, IL-17 and tumour necrosis factor-α (TNF-α) in Chinese Han patients with gout and hyperuricaemia.

Methods

This randomized, double-blind, placebo-controlled pilot study enrolled patients with gout and hyperuricaemia (sUA ≥ 8 mg/dl). Patients were randomized to receive either febuxostat 80 mg or placebo once daily for 24 weeks. The serum levels of sUA, IL-6, IL-17 and TNF-α were measured at weeks 0 (baseline), 2, 4, 8, 12, 16 and 24. Baseline clinical and demographic characteristics were recorded for all patients.

Results

A total of 156 patients were randomized: placebo group (n = 78) and febuxostat group (n = 78). The febuxostat group showed a significantly greater reduction in sUA compared with the placebo group. Serum uric acid concentration was reduced below 8 mg/dl in 46 of 61 patients (75.4%) by week 24. There were also reductions in the serum levels IL-6, IL-17 and TNF-α in the febuxostat group. In the febuxostat group, 10 of 78 patients (12.82%) discontinued treatment due to adverse drug reactions.

Conclusion

Febuxostat reduced the levels of sUA, TNF-α, IL-6 and IL-17, but there were some side-effects.

A Randomized Pilot Study of DASH Patterned Groceries on Serum Urate in Individuals with Gout

The Dietary Approaches to Stop Hypertension (DASH) diet reduces serum urate (SU); however, the impact of the DASH diet has not been previously evaluated among patients with gout. We conducted a randomized, controlled, crossover pilot study to test the effects of ~$105/week ($15/day) of dietitian-directed groceries (DDG), patterned after the DASH diet, on SU, compared with self-directed grocery shopping (SDG). Participants had gout and were not taking urate lowering therapy. Each intervention period lasted 4 weeks; crossover occurred without a washout period. The primary endpoint was SU. Compliance was assessed by end-of-period fasting spot urine potassium and sodium measurements and self-reported consumption of daily servings of fruit and vegetables. We randomized 43 participants (19% women, 49% black, mean age 59 years) with 100% follow-up. Mean baseline SU was 8.1 mg/dL (SD, 0.8). During Period 1, DDG lowered SU by 0.55 mg/dL (95% CI: 0.07, 1.04) compared to SDG by 0.0 mg/dL (95% CI: −0.44, 0.44). However, after crossover (Period 2), the SU difference between groups was the opposite: SDG reduced SU by −0.48 mg/dL (95% CI: −0.98, 0.01) compared to DDG by −0.05 mg/dL (95% CI: −0.48, 0.38; P for interaction by period = 0.11). Nevertheless, DDG improved self-reported intake of fruit and vegetables (3.1 servings/day; 95% CI: 1.5, 4.8) and significantly reduced total spot urine sodium excretion by 22 percentage points (95% CI: −34.0, −8.6). Though relatively small in scale, this pilot study suggests that dietitian-directed, DASH-patterned groceries may lower SU among gout patients not on urate-lowering drugs. However, behavior intervention crossover trials without a washout period are likely vulnerable to strong carryover effects. Definitive evaluation of the DASH diet as a treatment for gout will require a controlled feeding trial, ideally with a parallel-design.

Serum Urate Polygenic Risk Score Can Improve Gout Risk Prediction: A Large-Scale Cohort Study

Gout is a painful inflammatory arthritis affecting more than 8 million Americans. Identifying high-risk patients in early life could potentially encourage people to adopt lifestyle changes to prevent gout. Polygenic risk score (PRS) provides an overall estimate of an individual's genetic liability to develop a disease and can be used for early identification of high-risk individuals. In this study, we validated a previously reported PRS in an independent cohort. The urate-PRS was constructed from 110 significant urate-associated variants identified in Europeans. Phenome-wide and PRS-wide association study showed the urate-PRS is highly specifically associated with gout (phecode: 274.10; beta = 1.495 [1.372, 1.619], p = 4.37e-124). Urate-PRS alone did not performed in the gout prediction (area under the receiver operating characteristic curve, AUROC = 0.640); however, the addition of PRS upon demographics significantly improved the model performance, yielding an AUROC of 0.804 from 0.777 (DeLong test p = 3.66e−9). Trans-ethnic PRS and European-specific PRS showed similar prediction performance. We observed increasing gout prevalence and odds ratio (OR) across the PRS quintiles. Our study showed 8.2% of the cohort had more than 2.5 odds for gout than remainders, indicating that urate-PRS may be a better marker than age and sex to stratify patient risk. With the rapid growth of large biorepositories, such as All of Us, urate-PRS can be applied quickly and widely in population to estimate individual's risk, providing a powerful tool for gout preventive purpose in population health.

Natural products for the management of hyperuricaemia and gout: a review

Hyperuricaemia is characterised by a high level of urate in the blood. The crystallisation of urate is considered a critical risk factor for the development of gout. Allopurinol and febuxostat have been commonly used medications to decrease the circulating urate levels. However, the use of these drugs is associated with undesired side effects. Therefore, the development of a new active, safety anti-hyperuricaemic and anti-inflammatory drug could be useful in gout therapy and is highly justified. Natural products have become a source of new pharmaceuticals due to their strong efficacy with less side effects, which relies on the comprising of complex bioactive compounds. There are a growing number of studies purporting decreasing serum urate with traditional medicines. This article was aimed to review these studies and identify which extracts promote urate reduction, along with their different mechanisms.

The Efficacy and Mechanism of Chinese Herbal Medicines in Lowering Serum Uric Acid Levels: A Systematic Review

Background. Chinese herbal medicines are widely used to lower serum uric acid levels. However, no systemic review summarizes and evaluates their efficacies and the underlying mechanisms of action. Objectives. To evaluate the clinical and experimental evidences for the effectiveness and the potential mechanism of Chinese herbal medicines in lowering serum uric acid levels. Methods. Four electronic databases PubMed, Wed of Science, the Cochrane Library and Embase were used to search for Chinese herbal medicines for their effects in lowering serum uric acid levels, dated from 1 January 2009 to 19 August 2020. For clinical trials, randomized controlled trials (RCTs) were included; and for experimental studies, original articles were included. The methodological quality of RCTs was assessed according to the Cochrane criteria. For clinical trials, a meta-analysis of continuous variables was used to obtain pooled effects. For experimental studies, lists were used to summarize and integrate the mechanisms involved. Results. A total of 10 clinical trials and 184 experimental studies were included. Current data showed that Chinese herbal medicines have promising clinical efficacies in patients with elevated serum uric acid levels (SMD: −1.65, 95% CI: −3.09 to −0.22; p = 0.024). There was no significant difference in serum uric acid levels between Chinese herbal medicine treatments and Western medicine treatments (SMD: −0.13, 95% CI: −0.99 to 0.74; p = 0.772). Experimental studies revealed that the mechanistic signaling pathways involved in the serum uric acid lowering effects include uric acid synthesis, uric acid transport, inflammation, renal fibrosis and oxidative stress. Conclusions. The clinical studies indicate that Chinese herbal medicines lower serum uric acid levels. Further studies with sophisticated research design can further demonstrate the efficacy and safety of these Chinese herbal medicines in lowering serum uric acid levels and reveal a comprehensive picture of the underlying mechanisms of action.

Gender-Specific Inverse Associations Between Beans Intake, Serum Urate Levels, and Hyperuricemia: A Cross-Sectional Analysis Based on the Henan Rural Cohort Study

Background and Aims: Beans are rich in purines, which are important substances that lead to elevated serum urate, especially exogenous purines. Few studies were conducted to assess the relationship between beans intake and serum urate or hyperuricemia, especially in rural people. The purpose of this study was to validate the association by gender in the rural Chinese population.

Methods: A total of 38,855 participants aged 18–79 years old were enrolled from the Henan Rural Cohort Study (Registration number: ChiCTR-OOC-15006699). Dietary data were collected using a validated food frequency questionnaire (FFQ). Linear regression models and logistic regression models were used to examine the associations between beans intake and serum urate levels or hyperuricemia. Restricted cubic spline regression was performed to display the dose–response relationship.

Results: In multivariate-adjusted linear regression, an inverse correlation was found between beans intake and serum urate level (the highest quartile Q4 vs. the bottom quartile Q1) in both men (P = 0.008) and women (P < 0.001). Per 10-g increment in beans intake was associated with 0.30 μmol/L decreased concentration of serum urate in men and 0.71 μmol/L in women. The multivariate-adjusted odds ratios (ORs) of hyperuricemia were 0.83 (0.71, 0.97) in men and 0.73 (0.63, 0.84) in women (Q4 vs. Q1). Per 10-g increment in beans intake created a 1% decreased risk of hyperuricemia in men and 3% in women. The cubic spline suggested a risk reduction for hyperuricemia with increasing intake of beans.

Conclusion: A higher beans intake was associated with a lower serum urate level and a reduced risk of hyperuricemia in both sexes, and the association was more pronounced in women.

Associations of BMI and Serum Urate with Developing Dementia: A Prospective Cohort Study

CONTEXT

Recent studies have suggested that a higher body mass index (BMI) and serum urate levels were associated with a lower risk of developing dementia. However, these reverse relationships remain controversial, and whether serum urate and BMI confound each other is not well established.

OBJECTIVES

To investigate the independent associations of BMI and urate, as well as their interaction with the risk of developing dementia.

DESIGN AND SETTINGS

We analyzed a cohort of 502 528 individuals derived from the UK Biobank that included people aged 37-73 years for whom BMI and urate were recorded between 2006 and 2010. Dementia was ascertained at follow-up using electronic health records.

RESULTS

During a median of 8.1 years of follow-up, a total of 2138 participants developed dementia. People who were underweight had an increased risk of dementia (hazard ratio [HR] = 1.91, 95% confidence interval [CI]: 1.24-2.97) compared with people of a healthy weight. However, the risk of dementia continued to fall as weight increased, as those who were overweight and obese were 19% (HR = 0.81, 95%: 0.73-0.90) and 22% (HR = 0.78, 95% CI: 0.68-0.88) were less likely to develop dementia than people of a healthy weight. People in the highest quintile of urate were also associated with a 25% (HR = 0.75, 95% CI: 0.64-0.87) reduction in the risk of developing dementia compared with those who were in the lowest quintile. There was a significant multiplicative interaction between BMI and urate in relation to dementia (P for interaction = 0.004), and obesity strengthens the protective effect of serum urate on the risk of dementia.

CONCLUSION

Both BMI and urate are independent predictors of dementia, and there are inverse monotonic and dose-response associations of BMI and urate with dementia.

Lack of effect of tart cherry concentrate dose on serum urate in people with gout

OBJECTIVES

Cherry concentrate has been suggested to reduce serum urate (SU) and gout flares. The aims of this study were to determine the magnitude of the effect of tart cherry concentrate on SU in people with gout, the most effective dose of tart cherry concentrate for lowering SU, and adverse effects.

METHODS

Fifty people with gout and SU > 0.36 mmol/l were recruited. Half were on allopurinol and half were on no urate-lowering therapy. Participants were randomized to receive tart cherry juice concentrate: placebo, 7.5 ml, 15 ml, 22.5 ml or 30 ml twice daily for 28 days. Blood samples were taken at baseline, then at 1, 3 and 5 h post cherry and then on days 1, 3, 7, 14, 21 and 28. The area under the curve for SU was calculated over the 28-day study period.

RESULTS

Cherry concentrate dose had no significant effect on reduction in SU area under the curve, urine urate excretion, change in urinary anthocyanin between day 0 and day 28, or frequency of gout flares over the 28-day study period (P = 0.76). There were 24 reported adverse events, with only one (hyperglycaemia) considered possibly to be related to cherry concentrate. Allopurinol use did not modify the effect of cherry on SU or urine urate excretion.

CONCLUSION

Tart cherry concentrate had no effect on SU or urine urate excretion. If there is an effect of cherry concentrate on gout flares over a longer time period, it is not likely to be mediated by reduction in SU.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR), https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=368887, ANZCTR 12615000741583).

Sex Differences in Urate Handling

Hyperuricemia, or elevated serum urate, causes urate kidney stones and gout and also increases the incidence of many other conditions including renal disease, cardiovascular disease, and metabolic syndrome. As we gain mechanistic insight into how urate contributes to human disease, a clear sex difference has emerged in the physiological regulation of urate homeostasis. This review summarizes our current understanding of urate as a disease risk factor and how being of the female sex appears protective. Further, we review the mechanisms of renal handling of urate and the significant contributions from powerful genome-wide association studies of serum urate. We also explore the role of sex in the regulation of specific renal urate transporters and the power of new animal models of hyperuricemia to inform on the role of sex and hyperuricemia in disease pathogenesis. Finally, we advocate the use of sex differences in urate handling as a potent tool in gaining a further understanding of physiological regulation of urate homeostasis and for presenting new avenues for treating the constellation of urate related pathologies.

Effect of Curcumin on Serum Urate in Asymptomatic Hyperuricemia: A Randomized Placebo-Controlled Trial

BACKGROUND/OBJECTIVE

Hyperuricemia leads to gout and renal complications and may increase cardiovascular risk. Curcumin inhibits xanthine oxidase and increases uricosuric activity and, as a result, decreases serum urate (SU). This randomized controlled trial aimed to determine the effects of curcumin versus placebo on SU in subjects with asymptomatic hyperuricemia (SU level ≥ 6 mg/dL in women or ≥ 7 mg/dL in men).

METHODS

Thirty-nine subjects with persistent hyperuricemia were randomized to receive curcumin (500-mg capsules twice daily, 20 subjects) or placebo (19 subjects). Primary outcome was the difference between SU before and 8 weeks after randomization. Secondary outcomes were differences between urine uric acid (UUA) clearance, fasting plasma glucose (FPG), and lipid profiles before and 8 weeks after randomization and adverse events.

RESULTS

Out of 39 subjects, there were no differences at baseline SU, UUA clearance, FPG, lipid profiles, and demographics between curcumin and placebo groups. After 8 weeks, SU was significantly decreased in both groups (6.9% in curcumin group, p = 0.002, and 5.0% in placebo group, p = 0.009). However, there was no difference in SU reduction between the two groups (p = 0.532). There were no differences in UUA, FPG, lipid profiles, or adverse events in either group at 8 weeks after randomization. The most common adverse event was diarrhea with no treatment required.

CONCLUSION

Curcumin was not superior to placebo in reducing serum urate and in increasing UUA clearance.

Association between Serum Urate and Risk of Hypertension in Menopausal Women with XDH Gene

Elevated serum urate (sUA) concentrations have been associated with an increased risk of hypertension. We aimed to examine the association of sUA concentration on the risk of hypertension in pre- and post-menopausal women and investigated the association between the polymorphism of the xanthine dehydrogenase gene and the risk of hypertension. Among 7294 women, 1415 premenopausal and 5879 postmenopausal women were recruited. Anthropometric parameters as risk factors of hypertension were identify by logistic regression models. In addition, we investigated an association between xanthine dehydrogenase gene and sUA and their combined associations on the risk of hypertension. Body mass index (BMI) and waist circumference (WC) were significantly increased in accordance to the increase of sUA levels (p < 0.001). Multivariate logistic regression analysis showed postmenopausal women with a high sUA and high BMI were 3.18 times more likely to have hypertension than in those with normal and lower sUA (Odds ratio: 3.18, 95% confidence interval: 2.54–3.96). Postmenopausal women with a high WC were 1.62 times more likely to have hypertension than in those with normal and lower sUA. Subjects with the AG genotype of rs206860 was found to be at lower risk of hypertension (odd ratio: 0.287, 95% confidence interval: 0.091–0.905, p = 0.033). This cross-sectional study indicated a high sUA is associated with a higher risk of hypertension in postmenopausal women. Further well-designed prospective studies in other populations are warranted to validate our results.

Corrigendum: Functional Urate-Associated Genetic Variants Influence Expression of lincRNAs LINC01229 and MAFTRR

[This corrects the article DOI: 10.3389/fgene.2018.00733.].

Is there a role for cherries in the management of gout?

Despite the availability of effective urate-lowering therapy (ULT) and anti-inflammatory drugs for the treatment of gout, there is considerable interest in novel treatment approaches. Patients with gout often have a multitude of comorbidities, leading to concern over drug–drug interactions and medication adverse events. The cherry is a small nutrient-rich fruit that has garnered a great deal of attention in recent years as a nonpharmacologic option for the treatment of a multitude of disease manifestations. Perhaps a quarter of patients with gout try cherries or cherry products to treat their gout, which have antioxidant and anti-inflammatory (IL-6, TNF-α, IL-1β, IL-8, COX-I and -II) properties, hypouricemic effects, and the ability to downregulate NFkB-mediated osteoclastogenesis. Based on these properties, cherries may reduce both the acute and chronic inflammation associated with recurrent gout flares and its chronic destructive arthropathy. In this review, we explore the potential benefits of cherries and cherry products as a nonpharmacologic option for the treatment of gout.

Consumption of 100% Tart Cherry Juice Reduces Serum Urate in Overweight and Obese Adults

BACKGROUND

Gout is a frequently occurring, complex rheumatologic form of inflammatory arthritis caused by the accumulation of serum uric acid (sUA) and deposition of uric acid crystals in the joints and tissues of the body. Hyperuricemia is also a significant independent risk factor for all-cause and cardiovascular morbidity and mortality and is associated with hypertension, diabetes, obesity, and osteoarthritis. However, patient adherence to prescribed urate-lowering therapies ranges from 20% to 70%, suggesting that other additional strategies, such as dietary intervention with specific, efficacious foods or beverages, may be necessary to mitigate the risk of arthritis, as well as other comorbidities. Tart cherry juice (TCJ) has been used for decades by some for gout based largely on anecdotal evidence of its efficacy and its antioxidant and anti-inflammatory properties.

OBJECTIVES

We designed this study to test the effect of TCJ on uricemia, lipidemia, glycemia, and inflammation in at-risk overweight and obese humans with a specific hypothesis that TCJ consumption would reduce sUA concentrations.

METHODS

In this randomized, placebo-controlled crossover study, we recruited overweight and obese participants with body mass index (BMI) >25.0 kg/m2 (n = 26, 18 women/8 men, 41 ±11 y; BMI 31.3 ± 6.0; 12 obese, 14 overweight) to consume 240 mL/d (8 oz/d) of either TCJ or placebo beverage, for 4 wk each with a 4-wk intervening washout period followed by 4 wk of the alternate beverage.

RESULTS

TCJ significantly reduced sUA concentration by 19.2% (P < 0.05) and reduced by 19.4% (P = 0.09) and 6.3% (P = 0.08) proinflammatory high-sensitivity C-reactive protein and monocyte chemoattractant protein-1, respectively. The participants in this study displayed risk ratios indicating increased cardiovascular disease risk and insulin resistance but no differences in the pre- and postintervention groups of either placebo or TCJ groups.

CONCLUSION

Collectively, the data suggest that 100% TCJ reduces sUA concentrations, mitigating hyperuricemia associated with gouty arthritis. This trial was registered at clinicaltrials.gov as NCT03636529.

Characterization of patients with chronic refractory gout who do and do not have clinically apparent tophi and their response to pegloticase

OBJECTIVES

To determine the characteristics and response to pegloticase of patients with chronic refractory gout with and without clinically apparent tophi.

METHODS

Results from two randomized controlled trials of pegloticase in patients with chronic refractory gout with clinically apparent tophi or without tophi were used to assess baseline and on-treatment between-group differences.

RESULTS

Patients with tophi were significantly older than those without tophi, had a significantly longer duration of disease, higher numbers of tender and swollen joints, higher Patient Global Assessment scores and Health Assessment Questionnaire-Disability Index scores, and lower Arthritis-Specific Health Index scores. Patients with tophaceous gout also had significantly lower scores for physical functioning, role physical, social functioning, and the physical component summary scores of the Short Form 36 vs patients without tophi. In addition, subjects with clinically apparent tophi had a significantly lower mean estimated glomerular filtration rate. Pegloticase treatment of tophaceous patients caused significant reductions in serum urate, flares, Patient Global Assessment, tender joints, swollen joints, Health Assessment Questionnaire-Disability Index, visual analogue scale pain and Short Form 36 Bodily Pain, whereas patients without tophi had significant improvement in serum urate, flares, Patient Global Assessment, tender joints, and Short Form 36 Bodily Pain, but not swollen joints, Health Assessment Questionnaire-Disability Index functional score or pain visual analogue scale. Treatment with pegloticase had no effect on estimated glomerular filtration rate despite significant lowering of the urinary uric acid: creatinine ratio.

CONCLUSION

Patients with chronic refractory gout and clinically apparent tophi have more severe disease as well as reduced renal function. Both groups experienced significant clinical benefit with pegloticase treatment, although no change in renal function was noted.

Lesinurad: Evaluation of Pharmacokinetic and Pharmacodynamic Interactions With Warfarin in Healthy Volunteers

Lesinurad is a selective uric acid reabsorption inhibitor approved for use in combination with xanthine oxidase inhibitors for the treatment of hyperuricemia associated with gout. In vitro, lesinurad was shown to be a weak inhibitor of cytochrome P450 (CYP)2C9 and a weak inducer of CYP3A4. Warfarin is a widely prescribed oral coumarin-based anticoagulant commonly prescribed in gout patients. In an open-label clinical study in healthy adult male subjects, the effects of multiple daily doses of 400 mg lesinurad on the pharmacokinetics and pharmacodynamics of a single dose of 25 mg warfarin (racemic mixture of R- and S- enantiomers) were evaluated. Lesinurad had no effect on the absorption or the exposure (area under the concentration-time curve [AUC] and peak concentration) of the more active S-warfarin enantiomer. A slight reduction (19%) in overall plasma exposure (AUC) was observed for the R-warfarin enantiomer. Lesinurad had no meaningful clinical impact on anticoagulation activity as measured by prothrombin time, activated partial thromboplastin time, and international normalized ratio of prothrombin time and Factor VII clotting activity. Overall, the administration of warfarin in the presence of multiple-dose lesinurad was devoid of clinically significant drug-drug interaction.

Functional Urate-Associated Genetic Variants Influence Expression of lincRNAs LINC01229 and MAFTRR

Genetic variation in the genomic regulatory landscape likely plays a crucial role in the pathology of disease. Non-coding variants associated with disease can influence the expression of long intergenic non-coding RNAs (lincRNAs), which in turn function in the control of protein-coding gene expression. Here, we investigate the function of two independent serum urate-associated signals (SUA1 and SUA2) in close proximity to lincRNAs and an enhancer that reside ∼60 kb and ∼300 kb upstream of MAF, respectively. Variants within SUA1 are expression quantitative trait loci (eQTL) for LINC01229 and MAFTRR, both co-expressed with MAF. We have also identified that variants within SUA1 are trans-eQTL for genes that are active in kidney- and serum urate-relevant pathways. Serum urate-associated variants rs4077450 and rs4077451 within SUA2 lie within an enhancer that recruits the transcription factor HNF4α and forms long range interactions with LINC01229 and MAFTRR. The urate-raising alleles of rs4077450 and rs4077451 increase enhancer activity and associate with increased expression of LINC01229. We show that the SUA2 enhancer region drives expression in the zebrafish pronephros, recapitulating endogenous MAF expression. Depletion of MAFTRR and LINC01229 in HEK293 cells in turn lead to increased MAF expression. Collectively, our results are consistent with serum urate variants mediating long-range transcriptional regulation of the lincRNAs LINC01229 and MAFTRR and urate relevant genes (e.g., SLC5A8 and EHHADH) in trans.

Serum urate levels and therapy in adults treated with long-term dialysis: a retrospective cross-sectional study

BACKGROUND

The management of gout in chronic kidney disease and end-stage renal disease is challenging and remains controversial. There are limited data on the use of urate-lowering therapy in people receiving dialysis.

AIM

To estimate the point prevalence of gout, gout treatment and achievement of target serum urate (SU) among adults treated with long-term dialysis.

METHODS

Three secular cohorts of adults receiving dialysis for at least 90 days on 1 February 2017, 1 January 2016 and 1 January 2015 were identified. Medical records were reviewed for SU concentrations. Results were compared between haemodialysis (HD) and peritoneal dialysis (PD), and participants prescribed and not prescribed urate-lowering therapy. The percentage reduction in SU 24- and 48-h post-HD was estimated based on data from a previous study. SU concentrations were then used to estimate the percentage time the SU was <0.36 mmol/L using linear interpolation.

RESULTS

Of 216 dialysis patients, 61 (point prevalence 28.2%, 95% confidence interval 22.35-34.8%) had a diagnosis of gout. The mean (SD) age among those with gout was 61 years (14.4), 46 (75.4%) were men and 18 (31.1%) identified as Māori or Pacific Island. Forty-two (68.9%) were prescribed allopurinol (mean (SD) dose 116.0 ± 66.9 mg/day). 46% had a predialysis SU ≤0.36 mmol/L on less than 25% of occasions and 23% were below target on 76-100% of occasions. SU was below target 41% of time, with no statistically significant difference in those on HD or PD (P = 0.39), and those prescribed or not prescribed allopurinol (P = 0.55).

CONCLUSIONS

Gout is experienced by approximately one in four adults treated with dialysis and two-thirds are prescribed allopurinol. A minority have SU at a target sufficient to prevent gout despite allopurinol and HD. A treat to target SU should be considered in those with SU above target.

Pharmacokinetics, pharmacodynamics, and tolerability of verinurad, a selective uric acid reabsorption inhibitor, in healthy Japanese and non-Asian male subjects

Purpose

Verinurad (RDEA3170) is a selective uric acid reabsorption inhibitor in clinical development for treatment of gout and asymptomatic hyperuricemia. This study evaluated verinurad pharmacokinetics, pharmacodynamics, and tolerability in healthy Japanese and non-Asian adult male subjects.

Methods

This was a Phase I, randomized, single-blind, placebo-controlled study. Panels of 8 Japanese subjects were randomized to receive oral verinurad (2.5–15 mg) or placebo administered as a single dose in a fasted and fed state and as once-daily doses for 7 days in a fed state. Eight non-Asian subjects received verinurad 10 mg as a single dose (fasted and fed) and multiple doses in the fed state. Serial plasma/serum and urine samples were assayed for verinurad and uric acid. Safety was assessed by adverse events and laboratory data.

Results

Of 48 randomized subjects, 46 (Japanese, 39; non-Asian, 7) completed the study. Following single or multiple doses in Japanese subjects, maximum plasma concentration (C_max) and area under the plasma concentration–time curve (AUC) increased in a near dose-proportional manner. Time to C_max (T_max) was ~1.25–2.0 hours with fasting. A moderate-fat meal delayed T_max (range 3.0–5.0 hours) and had a variable effect on AUC (0%–97% increase) and C_max (0%–26% increase) across the dose groups. Following multiple verinurad 10 mg doses, C_max and AUC were 38% and 23% higher, respectively, in Japanese vs non-Asian subjects, largely due to body weight differences. Mean reduction of serum urate following multiple verinurad 10 mg doses was 46% and 44% after 24 hours in Japanese and non-Asian subjects, respectively. Verinurad was well tolerated at all doses.

Conclusion

Verinurad monotherapy lowered serum urate and was well tolerated in both healthy Japanese and non-Asian males, while small differences in plasma pharmacokinetics were observed. These data support further evaluation of once-daily verinurad as a treatment for gout and asymptomatic hyperuricemia.

The Effect of Lesinurad in Combination With Allopurinol on Serum Uric Acid Levels in Patients With Gout

The objective of the study was to evaluate the effect of lesinurad, a selective uric acid uptake inhibitor, alone and in combination with the xanthine oxidase inhibitor allopurinol, on serum uric acid and urinary urate excretion in patients with gout and hyperuricemia. A phase 1b, multicenter, open‐label, multiple‐dose study was carried out in patients with gout with serum uric acid ≥8 mg/dL following washout of urate‐lowering therapy. Patients were treated with allopurinol 300 mg/day alone in week 1; lesinurad 400 or 600 mg/day was added in week 2, followed by lesinurad 400 or 600 mg/day alone in week 3. Serum uric acid and urine uric acid were evaluated each week. Safety was assessed throughout the study. Lesinurad 400 or 600 mg/day added to allopurinol 300 mg/day reduced serum uric acid by 60% and 72%, respectively, versus allopurinol alone (37%) or lesinurad 400 mg/day (44%) or 600 mg/day (47%) alone. A 100% response rate of serum uric acid <6 mg/dL was achieved by all combinations (serum uric acid <5 mg/dL by 50%‐90%). Mean 24‐hour urate excretion compared with baseline was –35% with allopurinol, +36% and +56.5% with lesinurad 400 mg/day and 600 mg/day, respectively, and –11.6% and –7.1% with the respective combination therapies. Treatments were well tolerated. In this phase 1 trial, lesinurad added to allopurinol resulted in greater serum uric acid reduction than did allopurinol or lesinurad monotherapy.

Hyperuricemia, Acute and Chronic Kidney Disease, Hypertension, and Cardiovascular Disease: Report of a Scientific Workshop Organized by the National Kidney Foundation

Urate is a cause of gout, kidney stones, and acute kidney injury from tumor lysis syndrome, but its relationship to kidney disease, cardiovascular disease, and diabetes remains controversial. A scientific workshop organized by the National Kidney Foundation was held in September 2016 to review current evidence. Cell culture studies and animal models suggest that elevated serum urate concentrations can contribute to kidney disease, hypertension, and metabolic syndrome. Epidemiologic evidence also supports elevated serum urate concentrations as a risk factor for the development of kidney disease, hypertension, and diabetes, but differences in methodologies and inpacts on serum urate concentrations by even subtle changes in kidney function render conclusions uncertain. Mendelian randomization studies generally do not support a causal role of serum urate in kidney disease, hypertension, or diabetes, although interpretation is complicated by nonhomogeneous populations, a failure to consider environmental interactions, and a lack of understanding of how the genetic polymorphisms affect biological mechanisms related to urate. Although several small clinical trials suggest benefits of urate-lowering therapies on kidney function, blood pressure, and insulin resistance, others have been negative, with many trials having design limitations and insufficient power. Thus, whether uric acid has a causal role in kidney and cardiovascular diseases requires further study.

Lesinurad monotherapy in gout patients intolerant to a xanthine oxidase inhibitor: a 6 month phase 3 clinical trial and extension study

Objective

To investigate the efficacy and safety of lesinurad, a selective uric acid reabsorption inhibitor, in a 6 month, phase 3 clinical trial and extension study.

Methods

Patients with gout who cannot take a xanthine oxidase inhibitor (XOI) and have serum uric acid (sUA) ⩾6.5 mg/dl were randomized to receive oral lesinurad (400 mg daily) or placebo. The primary endpoint was the proportion of patients with sUA <6.0 mg/dl at month 6. Safety assessments included treatment-emergent adverse events (TEAEs) and laboratory data. Patients who completed the study were eligible for an open-label, uncontrolled extension study of lesinurad 400 mg monotherapy.

Results

Patients (n = 214) were primarily white males (mean age 54.4 years; gout duration 11.2 years). Significantly more patients achieved the primary endpoint with lesinurad than placebo (29.9 vs 1.9%; P < 0.0001). Overall TEAE rates were higher with lesinurad (77.6 vs 65.4%); renal-related TEAEs (17.8%), renal-related serious TEAEs (4.7%) and serum creatinine elevations (1.5 times baseline, 24.3%) occurred only with lesinurad. A total of 143 patients (65 lesinurad, 78 placebo) enrolled in the extension study. Treatment with lesinurad 400 mg resulted in rapid and sustained sUA lowering that persisted for up to 18 months before the study was terminated prematurely. No new safety findings were observed in the extension.

Conclusion

In patients with gout and intolerance/contraindication to XOIs, lesinurad 400 mg monotherapy demonstrated superior sUA lowering compared with placebo, with sustained effects for up to 18 months. Due to a high incidence of serum creatinine elevations and renal-related adverse events, including serious adverse events with lesinurad 400 mg, lesinurad should not be used as monotherapy.

Trial registration

ClinicalTrials.gov (http://clinincaltrials.gov), NCT01508702.

Elevated serum urate is a potential factor in reduction of total bilirubin: a Mendelian randomization study

Aim

A Mendelian randomization study (MRS) can be linked to a "natural" randomized controlled trial in order to avoid potential bias of observational epidemiology. We aimed to study the possible association between serum urate (SU) and total bilirubin (TBIL) using MRS.

Materials and Methods

An observational epidemiological study using ordinary least squares (OLS) regression and MRS using two-stage least square (TLS) regression was conducted to assess the effect of SU on TBIL. The comparison between the OLS regression and the TLS regression was analyzed by the Durbin-Hausman test. If the p value is significant, it suggests that the OLS regression cannot evaluate the relationship between exposure and outcome, and the TLS regression is precise; while if the p value is not significant, there would be no significant difference between the two regressions.

Results

A total of 3,753 subjects were analyzed. In OLS regression, there was no significant association between SU and TBIL in all subjects and subgroup analysis (all p > 0.05). However, MRS revealed a negative correlation between SU and TBIL after adjustment for confounders (beta = -0.021, p = 0.010). Further analysis was conducted in different SU subgroups, and results show that elevated SU was associated with a significant reduction in TBIL after adjustment for hyperuricemic subjects (beta = -0.053, p = 0.027). In addition, the results using the Durbin-Hausman test further confirmed a negative effect of SU on TBIL (p = 0.002 and 0.010, respectively).

Conclusions

This research shows for the first time that elevated SU was a potential causal factor in the reduction of TBIL and it provides strong evidence to resolve the controversial association between SU and TBIL.

Effect of Febuxostat on Ambulatory Blood Pressure in Subjects With Hyperuricemia and Hypertension: A Phase 2 Randomized Placebo-Controlled Study

Background

Hyperuricemia is associated with hypertension, with elevated serum uric acid levels postulated to have a causal role in the development of hypertension. Consequently, serum uric acid reduction may help lower blood pressure (BP). A Phase 2, double‐blind, placebo‐controlled trial was conducted to assess the potential BP‐lowering effects of the xanthine oxidase inhibitor febuxostat in subjects with hypertension and hyperuricemia (serum uric acid ≥0.42 mmol/L [≥7.0 mg/dL]).

Methods and Results

Subjects (n=121) were randomized 1:1 to febuxostat 80 mg once daily or to placebo. The primary end point was change from baseline to Week 6 in 24‐hour mean ambulatory systolic BP (SBP). Additional end points included the following: change from baseline to Week 3 in 24‐hour mean SBP and changes from baseline to Weeks 3 and 6 in 24‐hour mean ambulatory diastolic BP, serum uric acid, mean daytime and nighttime ambulatory SBP/diastolic BP, and clinic SBP/diastolic BP. For the overall study population, there were no significant differences between febuxostat and placebo for changes from baseline to Weeks 3 or 6 in ambulatory, daytime or nighttime, or clinic SBP or diastolic BP. However, in a preplanned subgroup analysis, there was a significant decrease in SBP from baseline to Week 6 in subjects with normal renal function (estimated glomerular filtration rate ≥90 mL/min) treated with febuxostat versus placebo; least squares mean difference, −6.7; 95% confidence interval −13.3 to −0.0; P=0.049.

Conclusions

This study suggests that febuxostat may lower BP in hyperuricemic patients with hypertension and normal renal function; further studies should be conducted to confirm this finding.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01496469.

Allopurinol dose escalation to achieve serum urate below 6 mg/dL: an open-label extension study

OBJECTIVES

To determine the long-term safety and efficacy of allopurinol dose escalation (DE) to achieve target serum urate (SU) in gout.

METHODS

People, including those with chronic kidney disease, who completed the first 12 months of a randomised controlled trial continued into a 12-month extension study. Participants randomised to continue current dose for the first 12 months began allopurinol DE at month 12 if SU was ≥6 mg/dL (control/DE). Immediate DE participants who achieved target SU maintained allopurinol dose (DE/DE). The primary endpoints were reduction in SU and adverse events (AEs) at month 24.

RESULTS

The mean (SE) change in SU from month 12 to 24 was -1.1 (0.2) mg/dL in control/DE and 0.1 (0.2) mg/dL in DE/DE group (p<0.001). There was a significant reduction in the percentage of individuals having a gout flare in the month prior to months 12 and 24 compared with baseline in both groups and in mean tophus size over 24 months, but no difference between randomised groups. There were similar numbers of AEs and serious adverse events between groups.

CONCLUSIONS

The majority of people with gout tolerate higher than creatinine clearance-based allopurinol dose and achieve and maintain target SU. Slow allopurinol DE may be appropriate in clinical practice even in those with kidney impairment.

TRIAL REGISTRATION NUMBER

ACTRN12611000845932.

Pharmacokinetics, pharmacodynamics, and tolerability of verinurad, a selective uric acid reabsorption inhibitor, in healthy adult male subjects

PURPOSE

Verinurad (RDEA3170) is a selective uric acid reabsorption inhibitor in clinical development for the treatment of gout and asymptomatic hyperuricemia. The aim of this study was to evaluate the pharmacokinetics, pharmacodynamics, and tolerability of verinurad in healthy adult males.

SUBJECTS AND METHODS

This was a Phase I, randomized, double-blind, placebo-controlled, single and multiple ascending dose study. Panels of eight male subjects received a single oral dose of verinurad or placebo in either a fasted or fed state; panels of 10-12 male subjects received ascending doses of once-daily verinurad or placebo in a fasted state for 10 days. Serial blood and urine samples were assayed for verinurad and uric acid. Safety was assessed by adverse event (AE) reports, laboratory tests, vital signs, and electrocardiograms (ECGs).

RESULTS

A total of 81 adult males completed the study. Following single doses of verinurad, maximum observed plasma concentration (C_max) and area under the plasma concentration-time curve (AUC) increased in a dose-proportional manner; C_max occurred at 0.5-0.75 hours and 1.25 hours in the fasted and fed states, respectively. Food decreased AUC by 23% and C_max by 37%-53%. There was a modest accumulation of verinurad following multiple daily doses. Verinurad reduced serum urate levels by up to 62% (40 mg, single dose) and 61% (10 mg, multiple dose). The increase in urinary excretion of uric acid was greatest in the first 6 hours after dosing and was still evident ≥24 hours for verinurad doses ≥2 mg. Verinurad was well tolerated at all doses. No serious AEs, severe AEs, discontinuations due to AEs, or clinically significant laboratory or ECG abnormalities were reported.

CONCLUSION

Single and multiple doses of verinurad were well tolerated, absorption was rapid, and exposure was dose proportional. Verinurad increased urinary uric acid elimination and resulted in sustained reductions in serum urate. These data support further clinical evaluation of once-daily verinurad as a treatment for gout.

Effects of renal function on pharmacokinetics and pharmacodynamics of lesinurad in adult volunteers

Introduction

Lesinurad is a selective uric acid reabsorption inhibitor approved for the treatment of gout in combination with a xanthine oxidase inhibitor (XOI) in patients who have not achieved target serum uric acid (sUA) levels with an XOI alone. Most people with gout have chronic kidney disease. The pharmacokinetics, pharmacodynamics, and safety of lesinurad were assessed in subjects with impaired renal function.

Methods

Two Phase I, multicenter, open-label, single-dose studies enrolled subjects with normal renal function (estimated creatinine clearance [eCrCl] >90 mL/min; N=12) or mild (eCrCl 60–89 mL/min; N=8), moderate (eCrCl 30–59 mL/min; N=16), or severe (eCrCl <30 mL/min; N=6) renal impairment. Subjects were given a single oral lesinurad dose of 200 mg (N=24) or 400 mg (N=18). Blood and urine samples were analyzed for plasma lesinurad concentrations and serum and urine uric acid concentrations. Safety was assessed by adverse events and laboratory data.

Results

Mild, moderate, and severe renal impairment increased lesinurad plasma area under the plasma concentration–time curve by 34%, 54%–65%, and 102%, respectively. Lesinurad plasma C_max was unaffected by renal function status. Lower renal clearance and urinary excretion of lesinurad were associated with the degree of renal impairment. The sUA-lowering effect of a single dose of lesinurad was similar between mild renal impairment and normal function, reduced in moderate impairment, and greatly diminished in severe impairment. Lesinurad increased urinary urate excretion in normal function and mild renal impairment; the increase was less with moderate or severe renal impairment. Lesinurad was well tolerated by all subjects.

Conclusion

Lesinurad exposure increased with decreasing renal function; however, the effects of lesinurad on sUA were attenuated in moderate to severe renal impairment.

Utility of the Morisky Medication Adherence Scale in gout: a prospective study

BACKGROUND

The outcomes of any chronic illness often depend on patients' adherence with their treatment. A tool is lacking to assess adherence in gout that is standardized, allows real-time feedback, and is easy to understand.

OBJECTIVE

We set out to evaluate the utility of the 8-item Morisky Medication Adherence Scale (MMAS-8) in monitoring medication adherence in a multiethnic Asian gout cohort on urate-lowering therapy (ULT).

METHODS

This cohort study recruited patients with gout where baseline and 6-monthly clinical data, self-report of adherence, and health status by Gout Impact Scale (GIS) and EuroQoL-5 dimension 3 levels were collected. Those who received at least 9 months of ULT were analyzed. Convergent and construct validities of MMAS-8 were evaluated against medication possession ratio (MPR) and known groups, clinical outcomes, and patient-reported outcomes. Internal consistency and test-retest reliability were assessed using Cronbach's alpha and intraclass correlation coefficient (ICC), respectively.

RESULTS

Of 91 patients, 92.3% were male, 72.5% Chinese with mean age 53.5 years. MMAS-8 (mean 6.17) and MPR (mean 96.3%) were poorly correlated (r=0.069, P=0.521). MMAS-8 did not differ between those who did or did not achieve target serum urate (SU) <360 µmol/L (P=0.852); or among those whose SU improved, stagnated, or worsened during follow-up (P=0.777). Adherence was associated with age (β=0.256, P=0.015) and education level (P=0.011) but not comorbidities, polypharmacy, or flare frequency. Concerns for medication side effects and anxiety or depression were associated with lower MMAS-8 (P<0.005). Internal consistency was acceptable (α=0.725) and test-retest reliability was satisfactory (ICC =0.70, 95% confidence interval [CI] 0.36-0.88).

CONCLUSION

MMAS-8 had limited construct validity in assessing medication adherence to ULT in our gout patients. Nevertheless, it identified patients bothered or worried about ULT side effects, and those with underlying anxiety or depression, for whom targeted education and coping support may be useful.

Effects of azelnidipine on uric acid metabolism in patients with essential hypertension

PURPOSE

To examine effects of a long-acting calcium channel blocker (CCB) azelnidipine on uric acid metabolism in hypertensive patients.

METHODS

Azelnidipine was administered to 72 patients at a daily dose of 8 mg or 16 mg. In 22 cases out of the 72 patients, a different CCB was switched to azelnidipine. Blood pressure was measured and biochemical parameters of blood and urine were evaluated before and 2-3 months after the administration.

RESULTS

Azelnidipine significantly decreased both systolic and diastolic blood pressure and the heart rate. It decreased both serum urate levels and the urinary uric acid to creatinine ratio (Uur/Ucr), but did not affect the uric acid clearance to creatinine clearance ratio (Cur/Ccr). Azelnidipine decreased both Uur/Ucr and Cur/Ccr in patients with Uur/Ucr ≥ 0.5 or ≥ 0.34, although it did not change these clearance parameters in patients with Uur/Ucr <0.5 or <0.34. Azelnidipine decreased the serum urate levels and Uur/Ucr in hyperuricemic patients with uric acid levels ≥ 7.0 mg/dL in males and ≥ 6.0 mg/dL in females. It did not change these parameters in normouricemic patients with serum urate levels <7.0 mg/dL in males and <6.0 mg/dL in females. Azelnidipine decreased Uur/Ucr and Cur/Ccr in hyperuricemic patients with normal or over excretion of uric acid, although it did not change these clearance parameters in hyperuricemic patients with uric acid hypoexcretion.

CONCLUSIONS

Azelnidipine decreased the serum urate acid levels and Uur/Ucr, and this response was most prominent in hyperuricemic patients or patients with normal and over excretion of uric acid.