A systematic review and meta-analysis on the safety and efficacy of febuxostat versus allopurinol in chronic gout

Two sides of the same coin: a complex presentation of autosomal dominant tubulointerstitial kidney diseases: a literature review and case reports

Introduction

Genetic kidney diseases are underdiagnosed; namely, from 7% to 40% of patients suffering from chronic kidney disease (CKD) can carry a pathogenic variant, depending on population characteristics. Hereditary tubulointerstitial kidney diseases, including autosomal dominant tubulointerstitial kidney diseases (ADTKD), are even more challenging to diagnose. ADTKD is a rare form of genetic kidney disease resulting from pathogenic variants in the MUC1, UMOD, HNF1B, REN, SEC61A1, and DNAJB11 genes. There is no typical clinical or histopathological sign of ADTKD, it is characterized by progressive CKD, an autosomal dominant inheritance pattern, and tubular atrophy with interstitial fibrosis on kidney biopsy. There is no significant proteinuria, and the urinary sediment is bland. The patients usually do not have severe arterial hypertension. There can be a history of early gout, especially when compared to the UMOD gene variants. Children can have enuresis due to a loss of renal concentration. On ultrasound, the kidneys can appear normal or small in size. Renal cysts are not pathognomonic for any of the named diseases. End-stage renal disease (ESRD) develops at the average age of 45, but this can be very variable. Family history that suggests autosomal dominant inheritance and CKD fulfilling the aforementioned characteristics of tubulointerstitial kidney disease should raise suspicion of ADTKD. In the setting of a negative family history for CKD, clinical suspicion should be raised based on clinical characteristics, including early onset of hyperuricemia or gout and compatible histology on the kidney biopsy. Contrary to the aforementioned characteristics of ADTKD, in the case of HNF1B-related disease, there is a more complex clinical presentation with extrarenal manifestations of the disease (diabetes mellitus, hypomagnesemia, neurologic and psychiatric disturbances, etc.). The diagnosis of ADTKD is based on a positive family history and a detection of the pathogenic variant in one of the genes in an affected individual.

Aim

The aim of our study is to present two case reports of ADTKD with different characteristics (slowly progressive CKD vs. complex clinical presentation with an extrarenal manifestation of the disease) with a literature review.

Methods

A 34-year-old patient with CKD and a positive family history of CKD in whom kidney biopsy showed nonspecific chronic changes, with only genetic analysis confirming the diagnosis of MUC1-related ADTKD. Our second case is of a 17-year-old patient with an unremarkable family history who was initially referred to genetic counseling due to cognitive and motor impairment with long-lasting epilepsy. Extensive workup revealed increased serum creatinine levels with no proteinuria and bland urinary sediment, along with hypomagnesemia. His genetic analysis revealed 17q12 deletion syndrome, causing the loss of one copy of the HNF1B gene, the AATF, and the LHX1 gene.

Conclusion

Autosomal dominant tubulointerstitial kidney diseases are challenging to diagnose due to a lack of typical clinical or histopathological signs as well as an uncharacteristic and versatile clinical presentation. Increased clinical awareness is crucial for the detection of these diseases.

Cardiovascular Safety Evaluation of Febuxostat and Allopurinol: Findings from the FDA Adverse Event Reporting System

BACKGROUND

Febuxostat and allopurinol are the most commonly used uric acid-lowering medications, and their safety is of great concern, especially the cardiovascular adverse reactions associated with febuxostat. We propose to study the cardiovascular toxicity of febuxostat and allopurinol using the FDA Adverse Event Reporting System (FAERS) database.

METHODS

A total of 64 quarters of FAERS data were downloaded from 2004 to 2019. Febuxostat- and allopurinol-related cardiovascular adverse events were extracted after data cleaning. Signal detection was conducted by reporting odds ratio (ROR) and proportional reporting ratio (PRR).

RESULTS

There were 2939 and 25,219 reports of febuxostat- and allopurinol-related cardiovascular adverse events (CVAEs), respectively. The most frequent CVAEs with febuxostat and allopurinol were edema peripheral (14.38%) and peripheral swelling (8.76%), respectively. In elderly gout patients, febuxostat is associated with an increased risk of heart failure, ischemic heart disease, hypertension, and cardiomyopathy. Febuxostat in combination with acetic acid derivatives nonsteroidal anti-inflammatory drug (NSAIDS) also increases the risk of cardiovascular adverse events.

CONCLUSIONS

Compared with allopurinol, febuxostat may increase cardiovascular toxicity in patients with gout.

The Hong Kong Society of Rheumatology consensus recommendations for the management of gout

Gout is one of the most common noncommunicable diseases in Hong Kong. Although effective treatment options are readily available, the management of gout in Hong Kong remains suboptimal. Like other countries, the treatment goal in Hong Kong usually focuses on relieving symptoms of gout but not treating the serum urate level to target. As a result, patients with gout continue to suffer from the debilitating arthritis, as well as the renal, metabolic, and cardiovascular complications associated with gout. The Hong Kong Society of Rheumatology spearheaded the development of these consensus recommendations through a Delphi exercise that involved rheumatologists, primary care physicians, and other specialists in Hong Kong. Recommendations on acute gout management, gout prophylaxis, treatment of hyperuricemia and its precautions, co-administration of non-gout medications with urate-lowering therapy, and lifestyle advice have been included. This paper serves as a reference guide to all healthcare providers who see patients who are at risk and are known to have this chronic but treatable condition.

Role of asymptomatic hyperuricemia in the progression of chronic kidney disease and cardiovascular disease

Previous research has investigated whether hyperuricemia serves as an independent risk factor for cardiovascular and renal diseases. Hyperuricemia is defined as an abnormally high level of uric acid (UA; i.e., serum urate level > 6.8 mg/dL). Hyperuricemia has been considered a complication of chronic kidney disease (CKD). However, it seems to play a pathogenic role in the progression of renal diseases. There has been increasing focus on the link between hyperuricemia and CKD. The results of randomized controlled trials have implied independent associations between hyperuricemia and the progression of cardiovascular and renal morbidities. These associations may be mediated by renin-angiotensin system activation, nitric oxide synthase inhibition, and macrovascular/microvascular disease development. There remains controversy regarding the use of serum UA level as an indirect index of renal vascular disease. This literature review focuses on the role of asymptomatic hyperuricemia in the progression of CKD, as well as the association between hyperuricemia and cardiovascular disease. It also provides a general overview of the physiological metabolism of UA.

Cardiovascular safety of febuxostat compared to allopurinol for the treatment of gout: A systematic and meta-analysis

The cardiovascular safety of febuxostat compared to allopurinol for the treatment of gout remains equivocal. Febuxostat had a better safety outcome compared with allopurinol. In this systematic review and meta-analysis, we searched MEDLINE and Embase for articles published between March 1, 2000 and April 4, 2021, without any language restrictions. We did a systematic review and meta-analysis of included clinical trials to evaluate the cardiovascular safety of febuxostat compared to allopurinol for treatment of chronic gout. Two reviewers independently selected studies, assessed study quality, and extracted data. Risk ratios were calculated with random effects and were reported with corresponding 95% confidence intervals (CI). From 240 potentially relevant citations, 224 papers were excluded; 16 studies were ultimately included in the analysis. Febuxostat had a better safety outcome compared with allopurinol，which was the composite of urgent coronary revascularization (OR: 0.84, 95% CI: 0.77-0.90, p < .0001) and stroke (OR: 0.87, 95% CI: 0.79-0.97, p = .009). However, that difference was not found in nonfatal myocardial infarction (OR: 0.99, 95% CI: 0.80-1.22, p = .91), cardiovascular related mortality (OR: 0.98, 95% CI: 0.69-1.38, p = .89) and all-cause mortality (OR: 0.93, 95% CI: 0.75-1.15, p = .52). No significant differences in cardiovascular related mortality and all-cause mortality were observed across any subgroup. This meta-analysis adds new evidence regarding the cardiovascular safety of febuxostat in patients. Initiation of febuxostat in patients was not associated with an increased risk of death or serious cardiovascular related adverse events compared with allopurinol.

Xanthine oxidase inhibition in SARS-CoV-2 infection: the mechanism and potency of allopurinol and febuxostat in COVID-19 management

The number of coronavirus disease 2019 (COVID-19) infection cases has been increasing globally, including in Indonesia. Definitive therapy for COVID-19 has not yet been found; hence, repurposed drugs for COVID-19 have been considered and have been practiced by several researchers in the world. This literature review investigates the action of xanthine oxidase as a component of the biomolecular pathway against severe acute respiratory syndrome-related coronavirus-2, the cause of COVID-19, and describes the mechanism and potential of uric acid drugs (allopurinol and febuxostat) as prophylaxis and curative therapy for COVID-19. 

Volumetric reduction and dissolution prediction of monosodium urate crystal during urate-lowering therapy - a study using dual-energy computed tomography

METHODS

Baseline and follow-up DECTs were performed under a standard ULT protocol. Monthly dissolution rates were calculated by simple and compound methods. Correlations with average SU were compared and analyzed. Best-fit regression model was identified. MSU dissolution times were plotted against SU at different endpoints.

RESULTS

In 29 tophaceous gout patients, MSU volume reduced from baseline 10.94 ± 10.59 cm³ to 2.87 ± 5.27 cm³ on follow-up (p = .00). Dissolution rate had a stronger correlation with SU if calculated by compound method (Pearson's correlation coefficient r= -0.77, p = .00) and was independent of baseline MSU load. The ensuing dissolution model was logarithmic and explained real-life scenarios. When SU > 0.43 mmol/l, dissolution time approached infinity. It improved to 10-19 months at SU = 0.24 mmol/l. When SU approximated zero (as with pegloticase), dissolution flattened and still took 4-8 months.

CONCLUSION

MSU dissolution is better described as a logarithmic function of SU, which explains, predicts, and facilitates understanding of the dissolution process.

Cost-effectiveness of allopurinol versus febuxostat in the treatment of gout patients: A systematic review

Background: In recent years, increased longevity, poor dietary habits, and the rising prevalence of metabolic syndrome and hypertension have increased the prevalence of gout. Gout significantly increases direct and indirect costs and reduces the quality of life. Allopurinol and febuxostat are the most commonly used drugs for reducing uric acid levels and controlling this disease with different cost-effectiveness. The present systematic review compares the cost-effectiveness of these drugs. Methods: This was a systematic review of economic evaluations. Cochrane CENTRAL, Web of Science, PubMed, Embase, and the Cost-Effectiveness Analysis (CEA) Registry were searched up to April 30, 2018, based on the specific search strategy of each database. Keywords used in the search include gout, cost-effectiveness, allopurinol, and febuxostat in MeSH and free-text forms. Screening of identified studies, data extraction, and quality assessment were done independently by 2 reviewers. The quality of studies was assessed based on Drummond Checklist. Finally, a qualitative analysis was done to analyze the results. Results: A total of 94 studies were identified through database search and the review of references. After screening the titles, abstracts, and full-texts, 6 economic evaluations were included in the review. The majority of the studies had been conducted in the US using the Markov model, within a 5-year horizon, and from the payer's perspective, with the quality of life as a measure of effectiveness. In most studies, the incremental cost-effectiveness ratios (ICERs) of febuxostat per quality-adjusted life year (QALY) were below the threshold (10 000$/QALY and 30 000€/QALY). Conclusion: Febuxostat has been shown to be more cost-effective than allopurinol in all treatment sequences in studies that have used uric acid levels as the measure of effectiveness. Furthermore, in studies with the quality of life as the measure of effectiveness, febuxostat has been shown to be very cost-effective as the second-line treatment.

Xanthine Oxidoreductase Inhibitors

Xanthine oxidase inhibitors are primarily used in the clinical prevention and treatment of gout associated with hyperuricemia. The archetypal xanthine oxidase inhibitor, Allopurinol has been shown to have other beneficial effects such as a reduction in vascular reactive oxygen species and mechano-energetic uncoupling. This chapter discusses these properties and their relevance to human pathophysiology with a focus on Allopurinol as well as newer xanthine oxidase inhibitors such as Febuxostat and Topiroxostat. Xanthine oxidase (XO) and xanthine dehydrogenase (XDH) are collectively referred to as xanthine oxidoreductase (XOR). XDH is initially synthesised as a 150-kDa protein from which XO is derived, e.g. under conditions of ischemia/hypoxia either reversibly by conformational changes (calcium or SH oxidation) or irreversibly by proteolysis, the latter leading to formation of a 130-kDa form of XO. Both, XO and XDH, catalyse the conversion of hypoxanthine via xanthine to uric acid, the former by using oxygen forming superoxide and hydrogen peroxide and the latter NAD⁺. However, XDH is in principle also able to generate ROS.

Comparison of efficacy and safety of urate-lowering therapies for hyperuricemic patients with gout: a meta-analysis of randomized, controlled trials

OBJECTIVES

To assess the efficacy and safety of the commonly used urate-lowering therapies (ULTs): febuxostat, allopurinol, and lesinurad in hyperuricemic patients with gout.

METHODS

We included all randomized controlled trials (RCTs) that compared ULTs with placebo or head to head. The primary efficacy endpoint was the proportion of subjects achieving the target serum urate (SU) level at month 6. Safety outcomes included total adverse events (AEs), serious AEs, withdrawals due to AEs, and AEs per organ system. A Bayesian network model was used to compare all ULTs with placebo and among themselves.

RESULTS

Fifteen RCTs were included for the analysis, in which 7968 patients were randomly assigned to take either placebo or one of 11 ULTs: allopurinol, febuxostat 40/80/120/240 mg/day, lesinurad 400 mg/day, lesinurad 200/400/600 mg/day plus allopurinol, and lesinurad 200/400 mg/day plus febuxostat. All ULTs were effective in achieving the target SU level at month 6 compared with placebo (ORs between 26.81 and 1928). Febuxostat 80/120/240 mg/day was superior to allopurinol and well tolerated for urate reduction. And as febuxostat dosage increased, more patients achieved the target SU level. Furthermore, the lesinurad combination with xanthine oxidase inhibitor (XOI) groups had a higher proportion of patients achieving the target SU level than the febuxostat 40 mg/day group (ORs between 2.89 and 9.17), the allopurinol group (ORs between 3.56 and 11.27), or the lesinurad 400 mg/day monotherapy group (ORs between 12.30 and 39.17) but might have a high risk of AEs.

CONCLUSIONS

All ULTs are effective in achieving the target SU level compared with placebo in hyperuricemic patients with gout. Lesinurad in combination with febuxostat or allopurinol is effective in urate lowering, especially for patients with inadequate response to XOI monotherapy. Key Points • All urate-lowering therapies (ULTs) were effective in achieving the target serum urate (SU) level at month 6 compared with placebo in hyperuricemic patients with gout. • Febuxostat 80/120/240 mg/day was superior to allopurinol and well tolerated for urate reduction. And as febuxostat dosage increased, more patients achieved the target SU level. • Lesinurad in combination with febuxostat or allopurinol was effective in urate lowering, especially for patients with inadequate response to xanthine oxidase inhibitor monotherapy, but might have a high risk of AEs.

New prenylflavonol glycosides with xanthine oxidase inhibitory activity from the leaves of Cyclocarya paliurus

Eight new prenylflavonol glycosides (1-8), along with five known analogues (9-13) were isolated from the n-butanol extract of the dried leaves of Cyclocarya paliurus (family Juglandaceae) for the first time. The structures of these compounds were characterized by comprehensive analysis of 1D, 2D NMR, HRESIMS, UV data and acid hydrolysis. In bioassay, all these thirteen prenylflavonol glycosides exhibited inhibitory effects on xanthine oxidase (XOD) activity. Especially compounds 2 and 7, showed outstanding IC₅₀ values of 31.81 ± 2.20 and 29.71 ± 3.69 μM, respectively.

Anti-hyperuricemia activity and toxicity prediction of a novel xanthine oxidoreductase inhibitor

A potent xanthine oxidoreductase inhibitor (LS087) was recently proved to exhibit a similar hypouricemic potency to febuxostat. A hyperuricemia model induced by potassium oxonate and hypoxanthine was proposed in specific pathogen-free male Kunming mice, and the serum urea nitrogen, creatinine and uric acid levels were measured after oral administration of LS087. Furthermore, renal histopathology was conducted by staining with hematoxylin and eosin, periodic acid-Schiff and Masson's trichrome stains, respectively. The results showed that the levels of serum urea nitrogen and uric acid significantly decreased compared with the model group, but the level of creatinine showed no significant changes. The pathological abnormalities in kidney tubules were improved after LS087 administration. Ten metabolites (M1-M10) of LS087 were identified after a single oral dosing of 10 mg/kg in rats. M6 was the primary LS087 metabolite in vivo with a pathway of methylation. The toxicity and potential risks of LS087 and its metabolites were predicted using the ProTox-II software. LS087 and the major metabolites (M2, M3, M5, M6, M7 and M8) were predicted to have no potential hepatotoxicity, but some metabolites with a total rate of <1% (M1, M4, M9, and M10) showed potential hepatotoxicity. M1 and M8 showed potential carcinogenicity. The LS087 biotransformation pathway in rat was well characterized.

Autosomal dominant tubulointerstitial kidney disease

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a recently defined entity that includes rare kidney diseases characterized by tubular damage and interstitial fibrosis in the absence of glomerular lesions, with inescapable progression to end-stage renal disease. These diseases have long been neglected and under-recognized, in part due to confusing and inconsistent terminology. The introduction of a gene-based, unifying terminology led to the identification of an increasing number of cases, with recent data suggesting that ADTKD is one of the more common monogenic kidney diseases after autosomal dominant polycystic kidney disease, accounting for ~5% of monogenic disorders causing chronic kidney disease. ADTKD is caused by mutations in at least five different genes, including UMOD, MUC1, REN, HNF1B and, more rarely, SEC61A1. These genes encode various proteins with renal and extra-renal functions. The mundane clinical characteristics and lack of appreciation of family history often result in a failure to diagnose ADTKD. This Primer highlights the different types of ADTKD and discusses the distinct genetic and clinical features as well as the underlying mechanisms.

Switching from allopurinol to febuxostat: efficacy and safety in the treatment of hyperuricemia in renal transplant recipients

The aim of this study was to evaluate the efficacy and tolerability of febuxostat in renal transplant recipients who were previously treated with allopurinol (the daily oral dose is 100 mg). A 6-month cohort study was conducted with 46 renal transplant recipients who had hyperuricemia. In 22 patients, treatment was changed from allopurinol to febuxostat (febuxostat was given at an oral dose of 20 mg once a day), and the other 24 patients continued the allopurinol treatment (the daily oral dose is 100 mg). The serum levels of uric acid (UA), creatinine, other biochemical parameters, estimated glomerular filtration rate (eGFR), and adverse events were measured at baseline as well as at 1, 3, and 6 months after the switch to febuxostat. Serum UA levels significantly decreased from 470.82 ± 34.37 to 378.77 ± 51.97 μmol/L in the febuxostat group, and decreased from 469.46 ± 33.47 to 428.21 ± 23.37 μmol/L in the allopurinol group. The eGFR increased from 75.55 to 85.23 mL/min in the febuxostat group, and decreased from 78.79 to 70.31 mL/min in the allopurinol group. In renal transplant recipients, febuxostat reduced the serum UA levels resulting in minor short-term improvement of renal function with no changes in the other biochemical parameters.

Febuxostat and Cardiovascular Events: A Systematic Review and Meta-Analysis

BACKGROUND

Febuxostat is approved in the United States for the management of hyperuricemia in patients with gout. In November 2017 the FDA released a warning alert on a possible link between febuxostat and cardiovascular disease (CVD) reported in a single clinical trial.

OBJECTIVE

To conduct a systematic review and meta-analysis and assess the risk of major adverse cardiovascular events (MACE) in patients receiving febuxostat compared to a control group.

METHODS

We searched the MEDLINE and EMBASE database for studies published up until March 2018. We included randomized clinical trials (RCTs) that compared febuxostat to control groups including placebo and allopurinol. We calculated the pooled relative risk (RR) of MACE and cardiovascular disease (CVD) mortality with the corresponding 95% confidence intervals (CI).

RESULTS

Our search yielded 374 potentially relevant studies. Among the 25 RCTs included in the systematic review, 10 qualified for the meta-analysis. Among the 14,402 subjects included, the median age was 54 years (IQR 52-67) and 90% were male (IQR 82-96); 8602 received febuxostat, 5118 allopurinol, and 643 placebo. The pooled RR of MACE for febuxostat was 0.9; 95% CI 0.6-1.5 (p= 0.96) compared to the control. The RR of CV-related death for febuxostat was 1.29; 95% CI 1.01-1.66 (p=0.03).

CONCLUSIONS

Compared with other SU-lowering treatments, febuxostat does not increase or decrease the risk of cardiovascular disease but may increase the risk of CVD death. More RCTs measuring cardiovascular safety as a primary outcome are needed to adequately evaluate the risk of CVD with febuxostat.

Comparison of efficacy and safety between febuxostat and allopurinol in early post-renal transplant recipients with new onset of hyperuricemia

What is known and objective

Febuxostat and allopurinol are xanthine oxidase inhibitors for urate‐lowering therapy. The efficacy and safety of febuxostat and allopurinol have been mostly reported in hyperuricemia patients with normal renal function. Here, we aimed to compare the effects of these two drugs in early post‐renal transplant recipients, focusing on evaluating the urate‐lowering effect and recovery of allograft renal function.

Methods

A retrospective cohort study was performed in early post‐renal transplant recipients with new onset of hyperuricemia receiving febuxostat or allopurinol therapy. Serum uric acid (UA) and estimated glomerular filtration rate (eGFR) were detected on days 3, 7 and 15 and months 1, 3 and 6 after therapy initiation. Liver and blood functions were monitored and other adverse events were recorded.

Results and discussion

A total of 48 and 33 patients were enrolled in the febuxostat and allopurinol groups, respectively. Significant UA‐lowering effects were observed on day 3 in both groups. Febuxostat caused a more rapid UA decline, starting on day 3 and lasting for 1 month. The most apparent contrast was found in UA level (267.25 ± 93.66 vs 334.18 ± 96.56 μmol/L, P = 0.003) on day 7; 62.5% and 30.3% of patients achieved target UA level in febuxostat and allopurinol groups respectively on day 3 (P = 0.004), but there was no significant difference between two groups from days 15 to months 6. The median times to achieve target UA level were 3 and 5 days in febuxostat and allopurinol groups respectively (P = 0.002). The eGFR levels and recovering rates were gradually upregulated but no significant differences were found between two groups. No abnormities related to febuxostat or allopurinol were observed.

What is new and conclusion

This is the first comprehensive evaluation of UA‐lowering effects of febuxostat and allopurinol in early post‐renal transplant recipients. Febuxostat caused a marginally quicker serum UA‐lowering effect than allopurinol, but there was no advantage for long‐term use of febuxostat. The drugs had no significant differences in impacting renal allograft function recovery, and both were well tolerated.

Efficacy and Safety of Lesinurad in Patients with Hyperuricemia Associated with Gout: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

To evaluate the efficacy and safety of lesinurad for the treatment of hyperuricemia in patients with gout.

DESIGN

Systematic review and meta-analysis of randomized controlled trials (RCTs).

PATIENTS OR PARTICIPANTS

Five RCTs, which included 1959 patients, compared the efficacy and safety of lesinurad in patients with hyperuricemia associated with gout.

MEASUREMENTS AND RESULTS

Relevant studies were identified from PubMed, EMBASE, Cochrane Library databases, and the ClinicalTrials.gov registry. Two reviewers independently assessed the studies. Individual effect sizes were standardized, and a meta-analysis was conducted to calculate the pooled effect size by using a random-effect model. The primary outcomes were the proportion of patients achieving target serum uric acid (sUA) levels by month 6 and the mean sUA levels at month 6 and month 12. Gout-related outcomes were also assessed. The secondary outcome was the number of treatment-emergent adverse events (TEAEs). Compared with xanthine oxidase inhibitor (XOI) monotherapy, lesinurad 200 mg or 400 mg in combination with allopurinol or febuxostat exhibited a higher proportion of patients achieving target sUA levels of < 6.0 mg/dl or < 5.0 mg/dl, respectively, by month 6. Lesinurad-plus-XOI groups also significantly sustained lower mean sUA levels at month 6 and month 12 compared to XOI alone group. In gout-related outcomes, no significant treatment group differences favored lesinurad. The number of TEAEs was comparable between the lesinurad 200 mg-plus-XOI group and the XOI-monotherapy group. Although lesinurad 400 mg monotherapy demonstrated superior efficacy compared with placebo, significantly more TEAEs occurred.

CONCLUSIONS

Although the combination of lesinurad 200 mg and XOI is effective and well tolerated for treating patients with gout who have not achieved an adequate response to XOI monotherapy, clinical gout-related outcomes were not improved. Therefore, additional studies investigating the long-term clinical implication of lesinurad are warranted.

"Yellow-dragon Wonderful-seed Formula" for hyperuricemia in gout patients with dampness-heat pouring downward pattern: a pilot randomized controlled trial

BACKGROUND

In Traditional Chinese Medicine (TCM) theories, the typical clinical manifestations of gout are attributed to the "dampness-heat pouring downward." Therefore, TCM practitioners always consider prescribing the formulae which are believed to clear heat and drain dampness for the management of gout. This clinical trial aims: (1) to determine the hypouricemic effect of "Yellow-dragon Wonderful-seed Formula" (YWF) decoction in gout patients with dampness-heat pouring downward pattern and (2) to determine if gypsum could provide additional significant benefits to YWF.

METHODS

A total of 72 hyperuricemic individuals with gout and dampness-heat pouring downward pattern were included with 62 of them completing the trial. Participants were randomly assigned to the YWF group, the YWF + gypsum group, or the allopurinol group. YWF and YWF + gypsum decoctions were orally administered for four weeks. Allopurinol was also orally administered for four weeks as the active control. Serum uric acid (sUA) level was the primary outcome measure. Urine urate level, scores on the SF-36 scale, erythrocyte sedimentation rate (ESR), X ray film, and C reactive protein (CRP) level were the secondary outcome measures.

RESULTS

Compared with the values at week 0, YWF and YWF + gypsum did not significantly decrease the sUA level at each weekend reading. YWF, YWF + gypsum, and allopurinol decreased the urine urate levels and there were significant differences between the YWF group and the YWF + gypsum group. All the changes in the eight structures of SF-36 during the intervention period were not significantly different among the three groups and there was no significant difference in the CRP level among the three groups at each weekend reading.

CONCLUSIONS

YWM, which modified on the basis of Two Wonderful Herbs Powder (2WHP), does not show significant hypouricemic effect. There is a possibility that Gypsum Fibrosum may provide additional effects to YWF in decreasing the urine urate levels but cannot add benefits to YWF in other outcome measures.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR-TRC-12001933 . Registered on 10 February 2012.

Efficacy and safety of febuxostat for treating hyperuricemia in patients with chronic kidney disease and in renal transplant recipients: A systematic review and meta-analysis

Febuxostat is potent and well-tolerated in the management of chronic gout. However, its clinical efficacy and safety in the treatment of hyperuricemia in patients with chronic kidney disease (CKD) and in renal transplant recipients have remained to be fully determined. The MEDLINE, EMBASE and Cochrane Library databases were searched for relevant articles. Data were extracted and pooled results were estimated from the standard mean difference (SMD) with 95% confidence intervals (95% CIs). The quality of the studies included was assessed, and their publication bias was examined. Four prospective randomized controlled trials and two retrospective observational studies were included in the systematic review and meta-analysis. Febuxostat administration significantly reduced the serum uric acid concentration in patients with CKD and in renal transplant recipients when compared with allopurinol or placebo in the short-term (1 month: SMD, −2.24; 95% CI, −3.59 to −0.89; P-value of SMD=0.001; I², 92.4%; 3 months: SMD, −1.20; 95% CI, −2.04 to −0.36; P-value of SMD=0.005; I², 88.9%; 6 months: SMD, −1.49; 95% CI, −2.68 to −0.30; P-value of SMD=0.014; I², 92.9%). Furthermore, the increase in the estimated glomerular filtration rate in the febuxostat group was significantly higher than that in the control group (SMD, 0.30; 95% CI, 0.031 to 0.58; P-value of SMD=0.029; I², 0.0%). No significant difference in the changes in serum creatinine (Scr), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) was identified between the two groups (Scr: SMD, −0.17; 95% CI, −0.97 to 0.63; P-value of SMD=0.67; I², 79.2%; LDL: SMD, −0.21; 95% CI, −0.49 to 0.07; P-value of SMD=0.13; I², 34.1%; HDL: SMD, −0.05; 95% CI, −0.70 to 0.61; P-value of SMD=0.89; I², 69.2%). In conclusion, febuxostat is a potent and well-tolerated agent for the short-term management of hyperuricemia in patients with CKD and in renal transplant recipients. However, these data should be interpreted with caution due to the varied design of the studies included in the present meta-analysis.

Management of hyperuricemia and gout in obese patients undergoing bariatric surgery

BACKGROUND

Hyperuricemia and gout represent important issues in the obese patients. Considering the epidemic trend of overweight and obesity in developed countries, the impact of these conditions is likely to increase. At present, bariatric surgery represents the most effective treatment for the management of severe obesity for reducing weight and the impact of associated comorbidities, but its effects on hyperuricemia and gout have not been fully elucidated.

METHODS

In this narrative review, we discuss the current knowledge about hyperuricemia and gout in obese patients undergoing bariatric surgery. We also suggest a useful approach to prevent gouty attacks in the perioperative period.

RESULTS

Weight loss seems to reduce hyperuricemia in the long-term follow-up, but there is evidence also of a high frequency of acute attacks early after surgery in patients with a diagnosis of gout.

CONCLUSION

Bariatric surgery has a high impact on hyperuricemia and gout. A perioperative approach is suggested, based on appropriate hydration, early physical resumption, urate lowering drugs and nonsteroidal anti-inflammatory drugs (NSAIDs), or colchicine and corticosteroids if NSAIDs are ineffective or not tolerated.

Side Effects and Interactions of the Xanthine Oxidase Inhibitor Febuxostat

The paper addresses the safety of febuxostat and summarizes reports on side effects and interactions of febuxostat published by the cut-off date (last day of literature search) of 20 March 2018. Publications on side effects and the interactions of febuxostat were considered. Information concerning the occurrence of side effects and interactions in association with the treatment with febuxostat was collected and summarized in the review. The incidence of severe side effects was much less frequent than mild side effects (1.2–3.8% to 20.1–38.7%). The rate and range of febuxostat side effects are low at doses of up to 120 mg and only increase with a daily dose of over 120 mg. The publications reveal no age-dependent increase in side effects for febuxostat. In patients with impaired renal function, no increase in adverse events is described with a dose of up to 120 mg of febuxostat per day. Patients with impaired liver function had no elevated risk for severe side effects. A known allopurinol intolerance increases the risk of skin reactions during treatment with febuxostat by a factor of 3.6. No correlation between treatment with febuxostat and agranulocytosis has been confirmed. Possible interactions with very few medications (principally azathioprine) are known for febuxostat. Febuxostat is well tolerated and a modern and safe alternative to allopurinol therapy.

A review on autosomal dominant tubulointerstitial kidney disease

In recent years there has been a reclassification of hereditary tubulointerstitial renal diseases. The old concepts of nephronoptisis or medullary cystic disease have been reordered based on the discovery of new genes. The 2015 KDIGO guidelines proposed a unification of terminology, diagnostic criteria and monitoring. So far 4genes causing autosomal dominant tubulointerstitial kidney disease have been described: MUC1, UMOD, HNF1B and REN. Although the mutation in each of them causes distinctive features in how they present, all have in common the progressive tubulointerstitial damage and renal fibrosis. In this article, we present a review of the guidelines and the literature, and some practical recommendations for dealing with this disease.

Population Pharmacodynamic Analysis of Uric Acid-Lowering Effects of Febuxostat Based on Electronic Medical Records in Two Hospitals

The aim of this study was to develop a population pharmacodynamic (PPD) model to describe uric acid (UA)-lowering effects in patients treated with febuxostat based on electronic medical records in 2 independent hospitals (university and city hospitals). Interhospital differences in the PPD model were also evaluated. We conducted the following 2 approaches to build the PPD models. A PPD model was developed separately using individual hospital data, and structural models and covariates between the two hospitals were compared (approach A). Another PPD model was developed using all available data from both hospitals, and differences between the 2 hospitals were evaluated by performing a covariate analysis on all PPD parameters (approach B). PPD analyses were performed by NONMEM using data from 358 patients. In both approaches, one indirect response model was established. In approach A, 2 diuretics (loops and thiazides) and renal function tests (Scr or BUN) were selected as covariates for the UA baseline level (serum UA levels just before the febuxostat treatment), whereas 2 diuretics and BUN were selected in approach B. A covariate analysis indicated that loops and thiazides increased UA baseline levels by 7%-14% and 6%-11%, respectively. In approach B, "hospital" was identified as a significant covariate for the UA baseline level; the baseline level was 7% higher in the city hospital. A PPD analysis may provide a precise description of the time course of the UA-lowering effects of febuxostat and quantitatively detect an interhospital difference in the UA baseline level.

Comparative effectiveness of allopurinol versus febuxostat for preventing incident renal disease in older adults: an analysis of Medicare claims data

OBJECTIVE

To assess the comparative effectiveness of allopurinol versus febuxostat for preventing incident renal disease in elderly.

METHODS

In a retrospective cohort study using 2006-2012 Medicare claims data, we included patients newly treated with allopurinol or febuxostat (baseline period of 183 days without either medication). We used 5:1 propensity-matched Cox regression analyses to compare the HR of incident renal disease with allopurinol use (and dose) versus febuxostat (reference). Sensitivity analyses included multivariable-adjusted regression models.

RESULTS

There were 31 465 new allopurinol or febuxostat treatment episodes in 26 443 patients; 8570 ended in incident renal disease. Crude rates of incident renal disease per 1000 person-years were 192 with allopurinol versus 338 with febuxostat. Crude rates of incident renal disease per 1000 person-years were lower with higher daily dose: allopurinol <200, 200-299 and ≥300 mg/day with 238, 176 and 155; and febuxostat 40 and 80 mg/day with 341 and 326, respectively. In propensity-matched analyses, compared with febuxostat, allopurinol use was associated with lower HR of incident renal disease, 0.61 (95% CI 0.49 to 0.77). Compared with febuxostat 40 mg/day, allopurinol doses <200, 200-299 and ≥300 mg/day were associated with lower HR of incident renal disease, 0.75 (95% CI 0.65 to 0.86), 0.61 (95% CI 0.52 to 0.73) and 0.48 (95% CI 0.41 to 0.55), respectively. Sensitivity analyses using multivariable-adjusted regression confirmed these findings.

CONCLUSIONS

Allopurinol was associated with a lower risk of incident renal disease in elderly patients than febuxostat. Future studies need to examine the mechanism of this potential renal benefit of allopurinol.

Management of Gout and Hyperuricemia in CKD

Hyperuricemia and gout, the clinical manifestation of monosodium urate crystal deposition, are common in patients with chronic kidney disease (CKD). Although the presence of CKD poses additional challenges in gout management, effective urate lowering is possible for most patients with CKD. Initial doses of urate-lowering therapy are lower than in the non-CKD population, whereas incremental dose escalation is guided by regular monitoring of serum urate levels to reach the target level of <6mg/dL (or <5mg/dL for patients with tophi). Management of gout flares with presently available agents can be more challenging due to potential nephrotoxicity and/or contraindications in the setting of other common comorbid conditions. At present, asymptomatic hyperuricemia is not an indication for urate-lowering therapy, though emerging data may support a potential renoprotective effect.

Effect of Rhizoma Polygoni Cuspidati and Ramulus Cinnamomi compatibility on uric acid metabolism and urinary neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 in rats with hyperuricemia

OBJECTIVE

To explore the effects of Rhizoma Polygoni Cuspidati and Ramulus Cinnamomi compatibility (PR) on uric acid metabolism and the expression of urinary neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) in rats with hyperuricemia.

METHODS

Seventy male Sprague Dawley (SD) rats were randomly divided into 7 groups with 10 rats per group, including the normal group, model group, allopurinol group, benzbromarone group and PR groups at 3 doses (3.5, 7, 14 g/kg). Except the normal group, rats of the other groups were intragastrically administered 100 mg/kg hypoxanthine and 250 mg/kg ethambutol, and subcutaneously injected with 200 mg/kg potassium oxonate. All rats were continuously modeled for 17 days, and gavaged with corresponding drugs. The rats of the normal and model groups were gavaged with saline, once a day, for 2 weeks. The levels of serum uric acid (SUA), blood urea nitrogen (BUN) and creatinine (Cr) were determined. In addition, the contents of NGAL and KIM-1 in urine and the mRNA and protein expressions of xanthine oxidase (XOD) in liver of hyperuricemia rats were measured by reverse transcription polymerase chain reaction (RT-PCR) and Western blot, respectively. Moreover, the pathological changes of kidney were analyzed by hematoxylin and eosin (HE) stain method.

RESULTS

Compared with the normal group, the levels of SUA, BUN, NGAL and KIM-1 and the expressions of hepatic XOD mRNA and protein in the hyperuricemia rats were increased signifificantly (P<0.01). PR signifificantly decreased the levels of SUA, BUN, NGAL and KIM-1 and down-regulated the mRNA and protein expressions of hepatic XOD (P<0.05 or P<0.01). In addition, the pathological changes of kidney were signifificantly suppressed by oral administration of PR.

CONCLUSIONS

PR ameliorated uric acid metabolism and protected renal function, the underlying mechanism was mediated by decreasing the levels of SUA, BUN, NGAL and KIM-1, inhibiting the expression of hepatic XOD and ameliorating the pathological change of kidney.

Identifying Patient Candidates for IL-1 Inhibition: Lessons From Real-World Cases

A subgroup of patients with gouty arthritis have a chronic recurring form that is particularly difficult to treat. Such patients experience repeated flares and often have abundant tophi. Many also have underlying comorbidities, such as renal impairment, cardiovascular disease, gastrointestinal disorders, obesity, and hypertension, which contraindicate the use of standard anti-inflammatory medications. Five patients with difficult to treat gouty arthritis who were either candidates and/or treated with anti-IL therapy are described.

Comparative efficacy and safety of urate-lowering therapy for the treatment of hyperuricemia: a systematic review and network meta-analysis

The prevalence of hyperuricemia and gout has been increasing, but the comparative effectiveness and safety of different treatments remain uncertain. We aimed to compare the effectiveness and safety of different treatments for hyperuricemia using network meta-analysis methodology. We systematically reviewed fifteen randomized controlled trials (involving 7,246 patients through January 2016) that compared the effects of different urate-lowering drugs (allopurinol, benzbromarone, febuxostat, pegloticase and probenecid) on hyperuricemia. Drug efficacy and safety, as outcomes, were measured by whether the target level of serum urate acid was achieved and whether any adverse events occurred, respectively. We derived pooled effect sizes expressed as odds ratios (ORs) and 95% confidence intervals (CIs). The efficacy and safety of the drugs were ranked by cumulative ranking probabilities. Our findings show that febuxostat, benzbromarone, probenecid, pegloticase, and allopurinol were all highly effective at reducing the risk of hyperuricemia compared to placebo. Febuxostat had the best efficacy and safety compared to the other drugs. Furthermore, febuxostat 120 mg QD was more effective at achieving urate-lowering targets (OR: 0.17, 95% CI: 0.12-0.24) and safer (OR: 0.72, 95% CI: 0.56-0.91) than allopurinol.

Rationale and design of a multicenter randomized study for evaluating vascular function under uric acid control using the xanthine oxidase inhibitor, febuxostat: the PRIZE study

BACKGROUND

Xanthine oxidase inhibitors are anti-hyperuricemic drugs that decrease serum uric acid levels by inhibiting its synthesis. Xanthine oxidase is also recognized as a pivotal enzyme in the production of oxidative stress. Excess oxidative stress induces endothelial dysfunction and inflammatory reactions in vascular systems, leading to atherosclerosis. Many experimental studies have suggested that xanthine oxidase inhibitors have anti-atherosclerotic effects by decreasing in vitro and in vivo oxidative stress. However, there is only limited evidence on the clinical implications of xanthine oxidase inhibitors on atherosclerotic cardiovascular disease in patients with hyperuricemia. We designed the PRIZE study to evaluate the effects of febuxostat on a surrogate marker of cardiovascular disease risk, ultrasonography-based intima-media thickness of the carotid artery in patients with hyperuricemia.

METHODS

The study is a multicenter, prospective, randomized, open-label and blinded-endpoint evaluation (PROBE) design. A total of 500 patients with asymptomatic hyperuricemia (uric acid >7.0 mg/dL) and carotid intima-media thickness ≥1.1 mm will be randomized centrally to receive either febuxostat (10-60 mg/day) or non-pharmacological treatment. Randomization is carried out using the dynamic allocation method stratified according to age (<65, ≥65 year), gender, presence or absence of diabetes mellitus, serum uric acid (<8.0, ≥8.0 mg/dL), and carotid intima-media thickness (<1.3, ≥1.3 mm). In addition to administering the study drug, we will also direct lifestyle modification in all participants, including advice on control of body weight, sleep, exercise and healthy diet. Carotid intima-media thickness will be evaluated using ultrasonography performed by skilled technicians at a central laboratory. Follow-up will be continued for 24 months. The primary endpoint is percentage change in mean intima-media thickness of the common carotid artery 24 months after baseline, measured by carotid ultrasound imaging.

CONCLUSIONS

PRIZE will be the first study to provide important data on the effects of febuxostat on atherosclerosis in patients with asymptomatic hyperuricemia. Trial Registration Unique trial Number, UMIN000012911 ( https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000015081&language=E ).

Kidney Disease in Adenine Phosphoribosyltransferase Deficiency

BACKGROUND

Adenine phosphoribosyltransferase (APRT) deficiency is a purine metabolism disorder causing kidney stones and chronic kidney disease (CKD). The course of nephrolithiasis and CKD has not been well characterized. The objective of this study was to examine long-term kidney outcomes in patients with APRT deficiency.

STUDY DESIGN

An observational cohort study.

SETTING & PARTICIPANTS

All patients enrolled in the APRT Deficiency Registry of the Rare Kidney Stone Consortium.

OUTCOMES

Kidney stones, acute kidney injury (AKI), stage of CKD, end-stage renal disease, estimated glomerular filtration rate (eGFR), and changes in eGFR.

MEASUREMENTS

Serum creatinine and eGFR calculated using creatinine-based equations.

RESULTS

Of 53 patients, 30 (57%) were females and median age at diagnosis was 37.0 (range, 0.6-67.9) years. Median duration of follow-up was 10.3 (range, 0.0-31.5) years. At diagnosis, kidney stones had developed in 29 (55%) patients and 20 (38%) had CKD stages 3 to 5, including 11 (21%) patients with stage 5. At latest follow-up, 33 (62%) patients had experienced kidney stones; 18 (34%), AKI; and 22 (42%), CKD stages 3 to 5. Of 14 (26%) patients with stage 5 CKD, 12 had initiated renal replacement therapy. Kidney stones recurred in 18 of 33 (55%) patients. The median eGFR slope was -0.38 (range, -21.99 to 1.42) mL/min/1.73m(2) per year in patients receiving treatment with an xanthine dehydrogenase inhibitor and -5.74 (range, -75.8 to -0.10) mL/min/1.73m(2) per year in those not treated prior to the development of stage 5 CKD (P=0.001).

LIMITATIONS

Use of observational registry data.

CONCLUSIONS

Progressive CKD and AKI episodes are major features of APRT deficiency, whereas nephrolithiasis is the most common presentation. Advanced CKD without a history of kidney stones is more prevalent than previously reported. Our data suggest that timely therapy may retard CKD progression.

Switching from allopurinol to febuxostat: efficacy and tolerability in hemodialysis patients

Background

Febuxostat is a novel xanthine oxidase inhibitor. However, few studies have examined the long-term efficacy and tolerability of febuxostat after switching from allopurinol in hemodialysis (HD) patients. Therefore, the present study evaluated the long-term efficacy and tolerability of febuxostat in HD patients after switching from allopurinol.

Findings

We monitored the levels of hemoglobin, hematocrit, platelet count, blood urea nitrogen, serum creatinine, serum sodium, serum potassium, serum chloride, serum calcium, serum inorganic phosphorus, aspartate transaminase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, and total protein that were considered overall as a tolerability index, while the serum uric acid (UA) level was considered an index of efficacy. All values were measured at baseline and at 1, 6, 12, and 16 months after the switch to febuxostat therapy. All subjects switched from allopurinol (100 mg/day) to febuxostat (10 mg/day) in August 2013. Clinical laboratory data were collected at baseline in July 2013 until December 2014. Nine patients were included in the study analysis. Results showed that clinical laboratory data at baseline versus those at 16 months were not significantly different. Serum UA levels, which represented the efficacy index, were significantly different between the baseline level (6.8 ± 1.4) and those at 1, 6, 12, and 16 months (5.2 ± 1.1, 5.1 ± 1.1, 4.6 ± 0.9, and 5.4 ± 1.8 mg/dL, respectively; all p < 0.05).

Conclusion

Switching from allopurinol to febuxostat in HD patients reduced serum UA levels, with no changes in other clinical laboratory data in the long term.

Autosomal dominant tubulointerstitial kidney disease: diagnosis, classification, and management--A KDIGO consensus report

Rare autosomal dominant tubulointerstitial kidney disease is caused by mutations in the genes encoding uromodulin (UMOD), hepatocyte nuclear factor-1β (HNF1B), renin (REN), and mucin-1 (MUC1). Multiple names have been proposed for these disorders, including 'Medullary Cystic Kidney Disease (MCKD) type 2', 'Familial Juvenile Hyperuricemic Nephropathy (FJHN)', or 'Uromodulin-Associated Kidney Disease (UAKD)' for UMOD-related diseases and 'MCKD type 1' for the disease caused by MUC1 mutations. The multiplicity of these terms, and the fact that cysts are not pathognomonic, creates confusion. Kidney Disease: Improving Global Outcomes (KDIGO) proposes adoption of a new terminology for this group of diseases using the term 'Autosomal Dominant Tubulointerstitial Kidney Disease' (ADTKD) appended by a gene-based subclassification, and suggests diagnostic criteria. Implementation of these recommendations is anticipated to facilitate recognition and characterization of these monogenic diseases. A better understanding of these rare disorders may be relevant for the tubulointerstitial fibrosis component in many forms of chronic kidney disease.

Asymptomatic hyperuricemia following renal transplantation

Evidence is accumulating indicating a role for uric acid in the genesis and progression of kidney disease, and a few studies are beginning to show a possible beneficial effect of urate-lowering therapy. Whether this holds true for renal allograft recipients is not clear. In this short review evidence from epidemiological as well as intervention studies is summarized and discussed, with some practical considerations presented at the end.

A phase 3, multicenter, randomized, allopurinol-controlled study assessing the safety and efficacy of oral febuxostat in Chinese gout patients with hyperuricemia

AIM

To compare the efficiency and safety of febuxostat with those of allopurinol in Chinese patients with gout and hyperuricemia.

METHODS

The trial which was conducted at 13 centers in China during 2011-2013 included a 2-week run-in and a 24-week treatment period. A total of 504 eligible participants with gout and with serum urate ≥ 480 μmol/L were randomly assigned 1 : 1 : 1 to febuxostat 40 mg/day, febuxostat 80 mg/day and allopurinol 300 mg/day groups. The primary efficacy endpoint was the percentage of subjects whose last three serum urate levels were < 360 μmol/L.

RESULTS

The primary efficacy endpoint was reached by 33.5% of subjects taking febuxostat 80 mg/day, 22.5% of those taking febuxostat 40 mg/day and 17.0% of those taking allopurinol 300 mg/day (P < 0.001 for the comparison between febuxostat 80 mg/day and allopurinol 300 mg/day groups; P = 0.216 for the comparison between febuxostat 40 mg/day and allopurinol 300 mg/day groups). The incidence of gout flare was relatively high in each group during the first 8 weeks and gradually decreased thereafter. There was no statistically significant difference between the three groups (P > 0.05). The incidence of adverse events was similar in the three treatment groups. The most frequent treatment-related adverse events were liver function test abnormalities.

CONCLUSIONS

Febuxostat 80 mg/day had superior urate-lowering efficacy to that of febuxostat 40 mg/day or allopurinol 300 mg/day, which was comparable in Chinese gout patients with hyperuricemia. Febuxostat, at a daily dose of 40 or 80 mg, was safe and well tolerated.

Allopurinol for chronic gout

BACKGROUND

Allopurinol, a xanthine oxidase inhibitor, is considered one of the most effective urate-lowering drugs and is frequently used in the treatment of chronic gout.

OBJECTIVES

To assess the efficacy and safety of allopurinol compared with placebo and other urate-lowering therapies for treating chronic gout.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE on 14 January 2014. We also handsearched the 2011 to 2012 American College of Rheumatology (ACR) and European League against Rheumatism (EULAR) abstracts, trial registers and regulatory agency drug safety databases.

SELECTION CRITERIA

All randomised controlled trials (RCTs) or quasi-randomised controlled clinical trials (CCTs) that compared allopurinol with a placebo or an active therapy in adults with chronic gout.

DATA COLLECTION AND ANALYSIS

We extracted and analysed data using standard methods for Cochrane reviews. The major outcomes of interest were frequency of acute gout attacks, serum urate normalisation, pain, function, tophus regression, study participant withdrawal due to adverse events (AE) and serious adverse events (SAE). We assessed the quality of the body of evidence for these outcomes using the GRADE approach.

MAIN RESULTS

We included 11 trials (4531 participants) that compared allopurinol (various doses) with placebo (two trials); febuxostat (four trials); benzbromarone (two trials); colchicine (one trial); probenecid (one trial); continuous versus intermittent allopurinol (one trial) and different doses of allopurinol (one trial). Only one trial was at low risk of bias in all domains. We deemed allopurinol versus placebo the main comparison, and allopurinol versus febuxostat and versus benzbromarone as the most clinically relevant active comparisons and restricted reporting to these comparisons here.Moderate-quality evidence from one trial (57 participants) indicated allopurinol 300 mg daily probably does not reduce the rate of gout attacks (2/26 with allopurinol versus 3/25 with placebo; risk ratio (RR) 0.64, 95% confidence interval (CI) 0.12 to 3.52) but increases the proportion of participants achieving a target serum urate over 30 days (25/26 with allopurinol versus 0/25 with placebo, RR 49.11, 95% CI 3.15 to 765.58; number needed to treat for an additional beneficial outcome (NNTB) 1). In two studies (453 participants), there was no significant increase in withdrawals due to AE (6% with allopurinol versus 4% with placebo, RR 1.36, 95% CI 0.61 to 3.08) or SAE (2% with allopurinol versus 1% with placebo, RR 1.93, 95% CI 0.48 to 7.80). One trial reported no difference in pain reduction or tophus regression, but did not report outcome data or measures of variance sufficiently and we could not calculate the differences between groups. Neither trial reported function.Low-quality evidence from three trials (1136 participants) indicated there may be no difference in the incidence of acute gout attacks with allopurinol up to 300 mg daily versus febuxostat 80 mg daily over eight to 24 weeks (21% with allopurinol versus 23% with febuxostat, RR 0.89, 95% CI 0.71 to 1.1); however more participants may achieve target serum urate level (four trials; 2618 participants) with febuxostat 80 mg daily versus allopurinol 300 mg daily (38% with allopurinol versus 70% with febuxostat, RR 0.56, 95% CI 0.48 to 0.65, NNTB with febuxostat 4). Two trials reported no difference in tophus regression between allopurinol and febuxostat over a 28- to 52-week period; but as the trialists did not provide variance, we could not calculate the mean difference between groups. The trials did not report pain reduction or function. Moderate-quality evidence from pooled data from three trials (2555 participants) comparing allopurinol up to 300 mg daily versus febuxostat 80 mg daily indicated no difference in the number of withdrawals due to AE (7% with allopurinol versus 8% with febuxostat, RR 0.89, 95% CI 0.62 to 1.26) or SAE (4% with allopurinol versus 4% with febuxostat, RR 1.13, 95% CI 0.71 to 1.82) over a 24- to 52-week period.Low-quality evidence from one trial (65 participants) indicated there may be no difference in the incidence of acute gout attacks with allopurinol up to 600 mg daily compared with benzbromarone up to 200 mg daily over a four-month period (0/30 with allopurinol versus 1/25 with benzbromarone, RR 0.28, 95% CI 0.01 to 6.58). Based on the pooled results of two trials (102 participants), there was moderate-quality evidence of no probable difference in the proportion of participants achieving a target serum urate level with allopurinol versus benzbromarone (58% with allopurinol versus 74% with benzbromarone, RR 0.79, 95% CI 0.56 to 1.11). Low-quality evidence from two studies indicated there may be no difference in the number of participants who withdrew due to AE with allopurinol versus benzbromarone over a four- to nine-month period (6% with allopurinol versus 7% with benzbromarone, pooled RR 0.80, 95% CI 0.18 to 3.58). There were no SAEs. They did not report tophi regression, pain and function.All other comparisons were supported by small, single studies only, limiting conclusions.

AUTHORS' CONCLUSIONS

Our review found low- to moderate-quality evidence indicating similar effects on withdrawals due to AEs and SAEs and incidence of acute gout attacks when allopurinol (100 to 600 mg daily) was compared with placebo, benzbromarone (100 to 200 mg daily) or febuxostat (80 mg daily). There was moderate-quality evidence of little or no difference in the proportion of participants achieving target serum urate when allopurinol was compared with benzbromarone. However, allopurinol seemed more successful than placebo and may be less successful than febuxostat (80 mg daily) in achieving a target serum urate level (6 mg/dL or less; 0.36 mmol/L or less) based on moderate- to low-quality evidence. Single studies reported no difference in pain reduction when allopurinol (300 mg daily) was compared with placebo over 10 days, and no difference in tophus regression when allopurinol (200 to 300 mg daily) was compared with febuxostat (80 mg daily). None of the trials reported on function, health-related quality of life or participant global assessment of treatment success, where further research would be useful.

Controlling serum uric acid using febuxostat in cancer patients at risk of tumor lysis syndrome

Tumor lysis syndrome (TLS) is a life-threatening oncological emergency, in which control of serum uric acid (S-UA) levels is important. S-UA-lowering efficacy of a new xanthine oxidase inhibitor, febuxostat, was retrospectively evaluated in seven patients with hematological malignancies who were at an intermediate risk of developing TLS. A 10-mg dose of febuxostat was initiated and chemotherapy was started within 24 h of administering the first dose of febuxostat. Febuxostat was continued until at least day 7 of chemotherapy treatment. The UA-lowering treatment was considered effective if febuxostat reduced S-UA levels to ≤7.5 mg/dl by day 5. The mean S-UA level at base line was 6.4±2.6 mg/dl and, on day 5, the mean S-UA level was 4.7±1.8 mg/dl. All the patients achieved S-UA levels ≤7.5 mg/dl. Serum creatinine levels decreased from 0.93±0.25 to 0.85±0.25 mg/dl. The estimated glomerular filtration rate values increased from 69.7±24.5 to 76.9±26.2 ml/min. No adverse reactions were noted during the study period and no patients experienced progressive TLS. Successful control of S-UA and improved renal function were obtained in response to febuxostat treatment in cancer patients at a risk of TLS.