Gout epidemiology: results from the UK General Practice Research Database, 1990-1999

Association between sex hormones and gout: An analysis of the UK Biobank cohort

OBJECTIVES

To investigate the associations between sex hormones and gout.

METHODS

A total of 448,836 individuals free of gout at baseline were included from the UK Biobank. Cox regression models were used to estimate hazard ratios (HRs) for gout. Besides, we investigated the causal relationship between bioavailable testosterone (BAT) and gout using mendelian randomization (MR).

RESULTS

There were differential effects in different testosterone active states in gout. One-unit higher log-transformed total testosterone (TT) was associated with a 52 % [95 % CI, 0.39-0.58] lower risk of gout in males. In contrast, free testosterone (FT) and BAT were associated with a 74 % [95 % CI, 1.38-2.20] and a 78 % [95 % CI, 1.41-2.25] higher risk of gout in males respectively. For MR, the weighted median [OR, 1.70; 95 % CI, 1.14-2.56;] and inverse variance-weighted [OR, 1.25; 95 % CI, 0.96-1.62; P = 0.09] method revealed significant and approximately significant positive effect of genetic liability to BAT levels on the risk of gout respectively.

CONCLUSIONS

Sex hormones were potentially associated with gout. Notably, we were the first to explore different testosterone states on gout and found that FT and BAT may increase the risk of gout in males, which is opposite to TT. And the former are active states of androgens, may be more accurately reflect the association between androgens and gout.

Progress of uric acid in cardiovascular disease

Due to the global prevalence of hyperuricemia (HUA), there is growing interest in research on uric acid (UA). HUA is a common condition that has various adverse consequences, including gout and kidney disease. However, recent studies have also implicated UA in the development of cardiovascular diseases (CVD) such as atrial fibrillation (AF) and coronary heart disease (CHD). Experimental and clinical research has extensively demonstrated the detrimental effects of elevated serum UA levels on cardiovascular health. Furthermore, serum UA levels have been identified as predictors of CVD outcomes following percutaneous coronary intervention (PCI) and catheter ablation. Additionally, the use of UA-lowering therapy holds important implications for the management of CVD. This review aims to consolidate the current evidence on the relationship between serum UA and CVD.

Cohort study investigating gout flares and management in UK general practice

BACKGROUND

Gout is the most common inflammatory arthritis and is almost exclusively managed in primary care, however the course and severity of the condition is variable and poorly characterised. This research aims improve understanding about the frequency of, and factors associated with, gout flares in the UK and characterise the factors associated with the initiation of ULT.

METHODS

Using the Clinical Practice Research Database, patients with a coded incident gout diagnosis without a prior prescription for urate-lowering therapy (ULT) were identified. Gout flares post diagnosis and ULT initiation were identified through prescribing and coded data. Patient characteristics, co-morbidities and co-prescribing were co-variants. Factors associated with gout flares and ULT initiation were analysed using cox-proportional hazard model and logistic regression.

RESULTS

Fifty-one thousand seven hundred eighty-four patients were identified: 18,605 (35.9%, 95%CI 35.5-36.3%) had experienced ≥ 1 recurrent flare, 17.4% (95%CI 17.1-17.8%) within 12 months of diagnosis. Male sex, black ethnicity, higher BMI, heart failure, CKD, CVD and diuretic use were associated with flares, with the highest HR seen with high serum urate levels (≥ 540 µmol/L HR 4.63, 95%CI 4.03-5.31). ULT initiation was associated with similar variables, although higher alcohol intake and older age were associated with lower odds of ULT initiation but were not associated with flares. ULT was initiated in 27.7% (95%CI 27.3-28.0%): 5.7% (95%CI 5.5-5.9%) within 12 months of diagnosis. ULT initiation rates were higher in patients with recurrent flares.

CONCLUSION

Approximately one in six people with incident gout had a second flare within 12 months. Factors associated with flare recurrence and ULT initiation were similar, but ULT initiation occurred later after diagnosis than previously thought.

Management of Gout in the Hand and Wrist

Gout, or monosodium urate deposition disease, is the most common form of inflammatory arthritis that affects almost 4% of adults in the United States.Medical management involves lifestyle modifications and urate-lowering therapy to reduce the frequency of gout flares, decrease the tophi size, and improve upper extremity function. Goals for surgical management of gout include functional optimization, symptomatic treatment, and cosmetic restoration.This article focuses on the medical and surgical treatment of the common manifestations of gout in the upper extremity including tophi, tenosynovitis, joint contractures, neural compression, and arthropathy.

Global, regional and national burdens of gout in the young population from 1990 to 2019: a population-based study

OBJECTIVE

To use data from the Global Burden of Disease (GBD) Study 2019 to report the global, regional and national rates and trends of annual incidence, point prevalence and years lived with disability (YLD) for gout in adolescents and young adults aged 15-39 years.

METHODS

We conducted a serial cross-sectional study of gout burden in the young population aged 15-39 years using data from GBD Study 2019. We extracted rates per 100 000 population of incidence, prevalence and YLD of gout, then calculated their average annual percentage changes (AAPCs) at the global, regional and national level between 1990 and 2019 by sociodemographic index (SDI).

RESULTS

The global gout prevalent cases in individuals aged 15-39 years was 5.21 million in 2019, with the annual incidence substantially increasing from 38.71 to 45.94 per 100 000 population during 1990-2019 (AAPC 0.61, 95% CI 0.57 to 0.65). This substantial increase was observed in all SDI quintiles (low, low-middle, middle, high-middle and high) and every age subgroup (15-19, 20-24, 25-29, 30-34 and 35-39 years). Males accounted for 80% of the gout burden. High-income North America and East Asia were facing a substantial increase in gout incidence and YLD simultaneously. Elimination of high body mass index can reduce 31.74% of the gout YLD globally in 2019, which varied from 6.97% to 59.31% regionally and nationally.

CONCLUSION

Gout incidence and YLD in the young population grew simultaneously and substantially in both developed and developing countries. Improving representative national-level data on gout, interventions for obesity and awareness in young populations are strongly suggested.

Sodium-glucose cotransporter-2 inhibitors and the risk of gout in patients with type 2 diabetes mellitus: A propensity-score-matched, new-user design study with an active comparator using the IQVIA Medical Research Data UK database

AIM

To conduct a pharmacoepidemiological study to explore the association between sodium-glucose cotransporter-2 (SGLT2) inhibitors and gout in patients with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

A retrospective open cohort study using the IQVIA Medical Research Data UK database was performed between November 1, 2012 and December 31, 2018, estimating the risk of gout in patients with T2DM who were new users of SGLT2 inhibitors, compared to propensity-score-matched new users of dipeptidyl peptidase-4 (DPP-4) inhibitors.

RESULTS

A total of 85 incident cases of gout were recorded over 30 389 person-years of observation in 13 617 new users of SGLT2 inhibitors and 29 426 new users of DPP-4 inhibitors. Crude incidence rates (IRs) per 1000 person-years were 2.90 and 2.47 for new users of SGLT2 inhibitors and DPP-4 inhibitors, respectively. The unadjusted hazard ratio (HR) was 1.18 (95% confidence interval [CI] 0.76-1.83). The adjusted HR was 1.20 (95% CI 0.77-1.86). In the at-treatment analysis, crude IRs per 1000 person-years were found to be 2.68 and 2.53 for SGLT2 inhibitor and DPP-4 inhibitor users, respectively. In the adjusted model, the adjusted HR was 1.3 (95% CI 0.90-2.29). Sensitivity analyses did not change the findings.

CONCLUSIONS

In this nationwide study, no difference in the incidence of gout was documented in patients treated with SGLT2 inhibitors compared to DPP-4 inhibitor users. This neutral finding remained consistent in sensitivity analyses.

Gene Dose-Dependent and Additive Effects of ABCG2 rs2231142 and SLC2A9 rs3733591 Genetic Polymorphisms on Serum Uric Acid Levels

This study aimed to evaluate whether the single nucleotide polymorphisms of ATP-binding cassette subfamily G member 2 (ABCG2) and solute carrier family 2 member 9 (SLC2A9) affect individual blood uric acid levels using pyrosequencing. ABCG2 (rs2231142, rs72552713, rs2231137), SLC2A9 (rs3734553, rs3733591, rs16890979), and individual uric acid levels were prospectively analyzed in 250 healthy young Korean male participants. Prominent differences in uric acid levels of the alleles were observed in the SLC2A9 rs3733591 polymorphism: wild-type (AA) vs. heterozygote (AG), 0.7 mg/dL (p < 0.0001); AA vs. mutant type (GG), 1.32 mg/dL (p < 0.0001); and AG vs. GG, 0.62 mg/dL (p < 0.01). In ABCG2 single nucleotide polymorphisms (SNPs), the statistically significant differences in uric acid levels were only found in rs2231142 between CC vs. AA (1.06 mg/dL; p < 0.001), and CC vs. CA (0.59 mg/dL; p < 0.01). Serum uric acid levels based on the ABCG2 and SLC2A9 diplotype groups were also compared. The uric acid levels were the lowest in the CC/AA diplotype and highest in the AA/AG diplotype. In addition, the SNP SLC2A9 rs3733591 tended to increase the uric acid levels when the ABCG2 rs2231142 haplotypes were fixed. In conclusion, both the ABCG2 rs2231142 and SLC2A9 rs3733591 polymorphisms may additively elevate blood uric acid levels.

Association between Dietary Fat Intake and Hyperuricemia in Men with Chronic Kidney Disease

Despite a close relationship between chronic kidney disease (CKD) and uric acid level, few studies have examined the relationship between uric acid level and fat intake by kidney function status. Therefore, we investigated the association between dietary fat intake and hyperuricemia with and without decreased kidney function in males living in Shika Town, Ishikawa Prefecture, Japan. This study included 361 males with a mean age of 60.7 years. Dietary fat and fatty acid intakes were evaluated using the brief-type self-administered diet history questionnaire. Reduced kidney function was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2, while hyperuricemia was defined as a serum uric acid level >7.0 mg/dL. A two-way analysis of covariance showed that saturated fatty acid (p = 0.026), monounsaturated fatty acid (p = 0.014), and polyunsaturated fatty acid (p = 0.022) were significantly lower in the high uric acid group than in the normal uric acid group. In multiple logistic analysis stratified by renal function, lipid intake was negatively associated with hyperuricemia in the low eGFR group. These findings suggest that higher dietary lipid/fatty acid intake may be effective in the prevention and treatment of hyperuricemia in men with CKD.

Association of Hyperuricemia with 10-Year Atherosclerotic Cardiovascular Disease Risk among Chinese Adults and Elders

The purpose of this cross-sectional study is to use a representative sample of the Chinese population and the atherosclerotic cardiovascular disease (ASCVD) risk assessment tool developed specifically for the Chinese to explore the prevalence of hyperuricemia (HUA) and the relationship between hyperuricemia and 10-year ASCVD risk in Chinese adults. Data was collected from the Chinese Physiological Constant and Health Condition survey. In this study, 12,988 subjects aged between 35 and 74 were selected by two-stage, cluster and random sampling. The sex-specific 10-year ASCVD risk scores equations, which were conducted by China-PAR project and specifically designed for Chinese adults, were used to assess the risk of developing ASCVD 10 years later. The ordinal regression model was used to explore the relationship between hyperuricemia and ASCVD risk. The total prevalence of hyperuricemia was 12.69%, and males’ prevalence was significantly higher than females (17.7% vs. 8.5%). Compared with people without hyperuricemia, the 10-year ASCVD risk scores of female with hyperuricemia increased significantly, but no significant increased happened in male. The ordinal regression model indicated that hyperuricemia subjects were 1.3 (males, 95% CI: 1.11–1.52) and 4.34 (females, 95% CI: 3.16–5.91) times more likely to increase their ASCVD risk levels than those without hyperuricemia. In conclusion, Hyperuricemia is prevalent among Chinese adults. In both genders, hyperuricemia was related with higher risk of 10-year ASCVD, and the relationship is much stronger in females than in males. Thus, sex-specific serum uric acid management and intervention strategies should be done in the prevention and control of cardiovascular events.

Egyptian consensus on treat-to-target approach of gout: evidence-based clinical practice guidelines for the management of gout

Introduction

New therapies, management approaches, and evidence regarding the management of gout have become available over the past years. This triggered the need for an updated recommendation for gout management. Through an up-to-date consensus evidence-based clinical practice guideline for the management of gout including recommendations for management of gout flares, optimum usage of urate lowering therapy for chronic gout, as well as patient education and lifestyle guidance. A wide systematic literature review was performed, and evidence-based recommendations were extrapolated, based on 16-key questions identified according to population, intervention, comparator, and outcomes (PICO) approach. These were evaluated by a panel consisted of 17 rheumatology experts via online surveys over a 2-round Delphi process. The purpose of this study is to offer an updated, consensus-evidence-based, and in the meantime patient-focused, expert recommendations for the treat-to-target approach of gout management.

Results

Results revealed that after round 2 ended, a total of 30-recommendation items, categorized into 10 domains, were obtained. Agreement with the recommendations (rank 7–9) ranged from 90 to 100%. Consensus was reached (i.e., ≥ 75% of respondents strongly agreed or agreed) on the wording, the grade of recommendation, and level of evidence of all the 30 clinical standards identified by the scientific committee.

Conclusions

This guideline provides updated evidence-based recommendations for the prevention and treatment of acute as well as chronic gout. This guideline provides an approach for physicians and patients making decisions on the management of gout. It will also facilitate improvement and uniformity of care.

Comparison of Rates of Lower Extremity Amputation in Patients With and Without Gout in the US Department of Veterans Affairs Health System

Importance

Cardiometabolic and other risk factors could render patients with gout more likely to undergo lower extremity amputation (LEA).

Objective

To examine the rate of and factors associated with LEA in patients with gout.

Design, Setting, and Participants

In this matched cohort study using national administrative data, multivariable Cox proportional hazards regression models were used to examine the associations of gout with LEA. In analyses limited to patients with gout, attributes of serum urate control and treatment with urate-lowering therapy were examined as factors associated with LEA. This study included patients who used US Department of Veterans Affairs services from January 1, 2000, to July 31, 2015. Patients with gout were identified using diagnostic codes and matched with up to 10 controls by age, sex, and year of benefit enrollment. Data analysis was performed from January 26, 2021, to September 3, 2021.

Exposures

Gout classification served as the primary independent variable of interest. In analyses limited to patients with gout, factors associated with serum urate control and urate-lowering therapy were examined.

Main Outcomes and Measures

Overall LEA, as well as toe, transmetatarsal, below-the-knee, and above-the-knee amputation.

Results

This cohort study included 5 924 918 patients, 556 521 with gout (mean [SD] age, 67 [12] years; 550 963 (99.0%) male; 88 853 [16.0%] Black non-Hispanic; 16 981 [4.3%] Hispanic/Latinx; 345 818 [62.1%] White non-Hispanic; 80 929 [14.5%] with race and ethnicity data missing; and 23 940 [4.3%] classified as other) and 5 368 397 without gout (mean [SD] age, 67 [12] years; 5 314 344 [99.0%] male; 558 464 [10.4%] Black non-Hispanic; 204 291 [3.0%] Hispanic/Latinx; 3 188 504 [59.4%] White non-Hispanic; 1 257 739 [23.4%)] with race and ethnicity data missing; and 159 399 [3.0%] classified as other). Compared with patients without gout, patients with gout were more likely to undergo amputation, an increased rate that remained after adjustment (adjusted hazard ratio, 1.20; 95% CI, 1.16-1.24) and was highest for below-the-knee amputation (adjusted hazard ratio, 1.59; 95% CI, 1.39-1.81). In those with gout, poor serum urate control (mean >7 mg/dL during the preceding year) was associated with a 25% to 37% increase in the rate of amputation. In contrast, treatment with urate-lowering therapy was not associated with the LEA rate.

Conclusions and Relevance

In this matched cohort study, patients with gout were more likely to undergo LEA. This increase was independent of other comorbidities that have been associated with amputation, including diabetes and peripheral vascular disease. Serum urate control was independently associated with the LEA rate, suggesting the possibility that lower extremity amputation may be preventable in some patients.

Pretreatment and Coadministration With Methotrexate Improved Durability of Pegloticase Response: An Observational, Proof-of-Concept Case Series

BACKGROUND/OBJECTIVE

Pegloticase is used for treatment of refractory gout, which has failed maximal medical management, but only 42% of patients respond completely to treatment because of the presumed development of antidrug antibodies, which rapidly clear the pegloticase molecule. Immunomodulatory medications temper antidrug antibody development in other diseases. The aim of this case series was to investigate the utility of adding methotrexate to a pegloticase regimen to increase the response durability in a real-world practice setting.

METHODS

In this multicenter, proof-of-concept, observational case series, refractory tophaceous gouty arthropathy patients being started on pegloticase 8 mg every 2 weeks were identified. The patients began oral methotrexate 15 mg/wk and folic acid 1 mg/d, 1 month prior to the initial pegloticase administration, and continued throughout pegloticase treatment. Responders were defined by demonstrating ≥80% of preinfusion serum uric acid (sUA) levels <6.0 mg/dL between months 3 and 6.

RESULTS

Ten sequential patients, aged 35 to 80 years, identified between May 2017 and June 2018, from 3 separate infusion centers were followed for up to 10 months. All patients maintained methotrexate 15 mg/wk without dose adjustments. There were 143 total pegloticase infusions. All 10 patients completed a full course of pegloticase treatment with 100% response and no infusion reactions. No patients stopped pegloticase therapy because of increased sUA, loss of response, or gout flares.

CONCLUSIONS

Pretreatment and coadministration of methotrexate with pegloticase resulted in 100% maintenance of pegloticase sUA response with no infusion reactions. These data support the potential use of immunomodulation with methotrexate to improve durability of pegloticase response in the treatment of refractory gout.

Inosine induces acute hyperuricaemia in rhesus monkey (Macaca mulatta) as a potential disease animal model

CONTEXT

The uric acid metabolism pathway is more similar in primates and humans than in rodents. However, there are no reports of using primates to establish animal models of hyperuricaemia (HUA).

OBJECTIVES

To establish an animal model highly related to HUA in humans.

MATERIALS AND METHODS

Inosine (75, 100 and 200 mg/kg) was intraperitoneally administered to adult male rhesus monkeys (n = 5/group). Blood samples were collected over 8 h, and serum uric acid (SUA) level was determined using commercial assay kits. XO and PNP expression in the liver and URAT1, OAT4 and ABCG2 expression in the kidneys were examined by qPCR and Western blotting to assess the effects of inosine on purine and uric acid metabolism. The validity of the acute HUA model was assessed using ulodesine, allopurinol and febuxostat.

RESULTS

Inosine (200 mg/kg) effectively increased the SUA level in rhesus monkeys from 51.77 ± 14.48 at 0 h to 178.32 ± 14.47 μmol/L within 30 min and to peak levels (201.41 ± 42.73 μmol/L) at 1 h. PNP mRNA level was increased, whereas XO mRNA and protein levels in the liver were decreased by the inosine group compared with those in the control group. No changes in mRNA and protein levels of the renal uric acid transporter were observed. Ulodesine, allopurinol and febuxostat eliminated the inosine-induced elevation in SUA in tested monkeys.

CONCLUSIONS

An acute HUA animal model with high reproducibility was induced; it can be applied to evaluate new anti-HUA drugs in vivo and explore the disease pathogenesis.

Colchicine for acute gout

BACKGROUND

This is an updated Cochrane Review, first published in 2006 and updated in 2014. Gout is one of the most common rheumatic diseases worldwide. Despite the use of colchicine as one of the first-line therapies for the treatment of acute gout, evidence for its benefits and harms is relatively limited.

OBJECTIVES

To update the available evidence of the benefits and harms of colchicine for the treatment of acute gout.

SEARCH METHODS

We updated the search of CENTRAL, MEDLINE, Embase, Clinicaltrials.gov and WHO ICTRP registries to 28 August 2020. We did not impose any date or language restrictions in the search.

SELECTION CRITERIA

We considered published randomised controlled trials (RCTs) and quasi-randomised controlled trials (quasi-RCTs) evaluating colchicine therapy compared with another therapy (placebo or active) in acute gout; low-dose colchicine at clinically relevant doses compared with placebo was the primary comparison. The major outcomes were pain, participant global assessment of treatment success (proportion with 50% or greater decrease in pain from baseline up to 32 to 36 hours), reduction of inflammation, function of target joint, serious adverse events, total adverse events and withdrawals due to adverse events.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as expected by Cochrane in this review update.

MAIN RESULTS

We included four trials (803 randomised participants), including two new trials, in this updated review. One three-arm trial compared high-dose colchicine (52 participants), low-dose colchicine (74 participants) and placebo (59 participants); one trial compared high-dose colchicine with placebo (43 participants); one trial compared low-dose colchicine with non-steroidal anti-inflammatory drugs (NSAIDs) (399 participants); and one trial compared low-dose colchicine with Chuanhu anti-gout mixture (traditional Chinese Medicine compound) (176 participants). We did not identify any trials comparing colchicine to glucocorticoids (by any route). The mean age of participants ranged from 51.2 to 70 years, and trial duration from 48 hours to 12 weeks. Two trials were at low risk of bias, one was possibly susceptible to selection bias (random sequence generation), reporting bias and other bias, and one open-label trial was at high risk of performance and detection bias. For the primary comparison, low-quality evidence from one trial (103 participants, downgraded for imprecision and bias) suggests low-dose colchicine may improve treatment outcome compared to placebo with little or no increased risk of adverse events. The number of people who reported treatment success (50% or greater pain reduction) at 32 to 36 hours was slightly larger with low-dose colchicine (418 per 1000) compared with placebo (172 per 1000; risk ratio (RR) 2.43, 95% confidence interval (CI) 1.05 to 5.64; absolute improvement 25% more reported success (7% more to 42% more, the 95% CIs include both a clinically important and unimportant benefit); relative change of 143% more people reported treatment success (5% more to 464% more). The incidence of total adverse events was 364 per 1000 with low-dose colchicine compared with 276 per 1000 with placebo: RR 1.32, 95% CI 0.68 to 2.56; absolute difference 9% more events with low-dose colchicine (9% fewer to 43% more, the 95% CIs include both a clinically important effect and no effect); relative change of 32% more events (32% fewer to 156% more). No participants withdrew due to adverse events or reported any serious adverse events. Pain, inflammation and function were not reported. Low-quality evidence (downgraded for imprecision and bias) from two trials (124 participants) suggests that high-dose colchicine compared to placebo may improve symptoms, but with increased risk of harms. More participants reported treatment success at 32 to 36 hours with high-dose colchicine (518 per 1000) compared with placebo (240 per 1000): RR 2.16, 95% CI 1.28 to 3.65, absolute improvement 28% (8% more to 46% more); more also had reduced inflammation at this time point with high-dose colchicine (504 per 1000) compared with placebo (48 per 1000): RR 10.50, 95% CI 1.48 to 74.38; absolute improvement 45% greater (22% greater to 68% greater); but more adverse events were reported with high-dose colchicine (829 per 1000 compared with 260 per 1000): RR 3.21, 95% CI 2.01 to 5.11, absolute difference 57% (26% more to 74% more). Pain and function were not reported. Low-quality evidence from a single trial comparing high-dose to low-dose colchicine indicates there may be little or no difference in benefit in terms of treatment success at 32 to 36 hours but more adverse events associated with the higher dose. Similarly, low-quality evidence from a single trial indicates there may also be little or no benefit of low-dose colchicine over NSAIDs in terms of treatment success and pain reduction at seven days, with a similar number of adverse events reported at four weeks follow-up. Reduction of inflammation, function of target joint and withdrawals due to adverse events were not reported in either of these trials, and pain was not reported in the high-dose versus low-dose colchicine trial. We were unable to estimate the risk of serious adverse events for most comparisons as there were few events reported in the trials. One trial (399 participants) reported three serious adverse (one in a participant receiving low-dose colchicine and two in participants receiving NSAIDs), due to reasons unrelated to the trial (low-quality evidence downgraded for bias and imprecision).

AUTHORS' CONCLUSIONS

We found low-quality evidence that low-dose colchicine may be an effective treatment for acute gout when compared to placebo and low-quality evidence that its benefits may be similar to NSAIDs. We downgraded the evidence for bias and imprecision. While both high- and low-dose colchicine improve pain when compared to placebo, low-quality evidence suggests that high-dose (but not low-dose) colchicine may increase the number of adverse events compared to placebo, while low-quality evidence indicates that the number of adverse events may be similar with low-dose colchicine and NSAIDs. Further trials comparing colchicine to placebo or other treatment will likely have an important impact on our confidence in the effect estimates and may change the conclusions of this review. There are no trials reporting the effect of colchicine in populations with comorbidities or in comparison with other commonly used treatments, such as glucocorticoids.

Prevalence of gout in the adult general population in Spain: Estimating the proportion of undiagnosed cases

OBJECTIVE

To estimate the prevalence of gout in Spain.

METHODS

Cross-sectional, population-based study of people aged 20 years or older. First, randomly selected individuals were contacted by telephone and rheumatic disease screening questionnaires were conducted. If the first screening was positive, medical records were then reviewed and/or a phone questionnaire was conducted by a rheumatologist, followed by an appointment if necessary. Newly diagnosed cases had to fulfil the ACR/EULAR 2015 criteria. To calculate the prevalence and its 95% CI, the sample design was taken into account and weighing was calculated according to age, sex and geographic origin.

RESULTS

In all, 4916 individuals were included, 1361 had a positive screening result for gout (59 of them reported a prior diagnosis). Of these, 51 were classified as missing and 95 were classified as gout cases. An additional case was detected through a positive screening for fibromyalgia and Sjögren's syndrome, although a previous gout diagnosis was confirmed by a review of the medical records. Of the 96 gout cases, 31 (32%) were de novo diagnoses. The estimated weighted prevalence of gout was 2.4% (95% CI 1.95-2.95), with a higher prevalence in men (4.55% [95%CI 3.65-5.65]) than women (0.38% [95%CI 0.19-0.76]).

CONCLUSION

EPISER2016 is the first population-based study to estimate the prevalence of gout in Spain. Undiagnosed patients accounted for a substantial proportion of cases, highlighting the need for population-approaches when estimating the prevalence of infra-diagnosed diseases. Reliable national approaches are key to obtaining accurate estimates of diseases to better aid healthcare and workforce planning.

Genetic-epidemiological analysis of hypouricemia from 4,993 Japanese on nonfunctional variants of URAT1/SLC22A12 gene

OBJECTIVES

Up to 0.3% of Japanese have hypouricemia. Most cases appear to result from a hereditary disease, renal hypouricemia (RHUC), which causes exercise-induced acute kidney injury and urolithiasis. However, to what extent RHUC accounts for hypouricemia is not known. We therefore investigated its frequency and evaluated its risks by genotyping a general Japanese population.

METHODS

A cohort of 4,993 Japanese was examined by genotyping the nonfunctional variants R90H (rs121907896) and W258X (rs121907892) of URAT1/SLC22A12, the two commonest causative variants of RHUC in Japanese.

RESULTS

Participants' fractional excretion of uric acid and risk allele frequencies markedly increased at lower SUA levels. Ten participants (0.200%) had a serum uric acid (SUA) level of ≤ 2.0 mg/dl and nine had R90H or W258X, likely to have RHUC. Logistic regression analysis revealed these URAT1 variants to be significantly and independently associated with the risk of hypouricemia and mild hypouricemia (SUA ≤ 3.0 mg/dl) as well as sex, age, and BMI, but these URAT1 variants were the only risks in the hypouricemia population (SUA ≤ 2.0 mg/dl). W258X was only the risk in males with SUA of ≤ 3.0 mg/dl.

CONCLUSION

Our study accurately reveals the prevalence of RHUC and provides genetic evidence for its definition (SUA ≤ 2.0 mg/dl). We also show that individuals with SUA of ≤ 3.0 mg/dl, especially males, are prone to RHUC. Our findings will help to promote a better epidemiological understanding of RHUC as well as more accurate diagnosis, especially in males with mild hypouricemia.

Gout Flare Burden, Diagnosis, and Management: Navigating Care in Older Patients with Comorbidity

Gout is the most common form of inflammatory arthritis, and its incidence is highest in middle-aged and older patients. Adding to the diagnostic complexity, up to 50% of patients aged > 65 years present atypically, with subacute oligo- or polyarticular flares. Comorbidity and polypharmacy, common in older populations, affect real-world treatment decisions in gout management, and no specific guidelines are available to address these issues in these at-risk groups. Despite the growing public health burden posed by gout, suboptimal management has led to increased morbidity and substantial healthcare utilization and cost burden, as reflected by an increased incidence of emergency department visits and hospitalizations in recent years. Colchicine, nonsteroidal anti-inflammatory drugs, or glucocorticoids (oral, intraarticular, or intramuscular) should be considered as first-line agents for gout flare management. Urate-lowering therapy, with the goal of lowering and maintaining serum urate concentrations at < 6 mg/dL (< 360 μmol/L), is recommended to achieve optimal outcomes, including regression of tophi, reduction (or elimination) of flares, and reductions in total urate burden. In this review, we summarize the current burden posed by gout and discuss best practices in its diagnosis and management, focusing on best practices in the context of gout flare in older patients with comorbid conditions.

Minimally Invasive Embedding of Saturated MSU Induces Persistent Gouty Arthritis in Modified Rat Model

Introduction

Animal models are valid for in vivo research on the pathophysiological process and drug screening of gout arthritis. Intra-articular injection of monosodium urate (MSU) is the most common method, while stable MSU deposition enveloped by inflammatory cells was rarely reported.

Objective

To develop a modified gouty arthritis rat model characterized by intra-articular MSU deposition and continuous joint pain with a minimally invasive method.

Method

A total of twenty-four rats were randomly allocated into six groups. Three intervention groups of rats received intra-articular MSU embedment. Sham groups received pseudosurgeries with equal normal saline (NS). Gross parameters and pathological features of synovium harvested from anterior capsule were estimated. Mechanical pain threshold tests were conducted over a 96-hour period postoperatively. Moreover, quantitative immunofluorescence was conducted to assess tissue inflammation.

Result

After MSU embedding, rats got more persistent arthritic symptoms as well as tissue MSU deposition. More significant synovial swelling was detected in the MSU group compared to sham groups (P < 0.025). Behavioral tests showed that the embedding of MSU resulted in prolonged mechanical hyperalgesia during 2 hours to 96 hours postoperatively (P < 0.05). MSU depositions enveloped by inflammatory cells that express IL-1β and TNF-α were detected in embedding groups. Quantitative immunofluorescence suggested that the frequencies of MSU interventions upregulated expression of proinflammatory factors including IL-1β and TNF-α (P < 0.05).

Conclusion

A minimally invasive method was developed to establish modified rat model of intra-articular MSU deposition. This model was proved to be a simple reproducible method to mimic the pathological characteristics of persistent gouty arthritis.

Identification of Gout Flares in Chief Complaint Text Using Natural Language Processing

Many patients with gout flares treated in the Emergency Department (ED) often do not receive optimal continuity of care after an ED visit. Thus, developing methods to identify patients with gout flares in the ED and referring them to appropriate outpatient gout care is required. While Natural Language Processing (NLP) has been used to detect gout flares retrospectively, it is much more challenging to identify patients prospectively during an ED visit where documentation is usually minimal. We annotate a corpus of ED triage nurse chief complaint notes for the presence of gout flares and implement a simple algorithm for gout flare ED alerts. We show that the chief complaint alone has strong predictive power for gout flares. We make available a de-identified version of this corpus annotated for gout mentions, which is to our knowledge the first free text chief complaint clinical corpus available.

Age-Specific Imbalance of Circulating Tfh Cell Subsets and Its Association With Gout-Targeted Kidney Impairment

Objective

Gout is a chronic disease characterized by the deposition of monosodium urate (MSU) crystals in tissue. Study with a focus on adaptive immune response remains to be understood although innate immune response has been reported extensively in gout etiology. Our study attempted to investigate the association of gout-related immune cell imbalance with clinical features and comorbidity with renal impairment and the implicated pathogenesis via the assessment of T and B cell subsets in different activity phases or with immune effects combined with the analyses of clinical parameters.

Methods

Fifty-eight gout patients and 56 age- and sex-matched healthy individuals were enrolled. To learn the roles of circulating T cells, a lymphocyte profile incorporating 32 T cell subsets was tested from isolated freshly peripheral blood monocyte cells (PBMCs) with multiple-color flow cytometry. Furthermore, the collected clinical features of participants were used to analyze the characteristics of these differential cell subsets. Stratified on the basis of the level of creatinine (Cr, enzymatic method), all patients were categorized into Cr^low (Cr ≤ 116 μmol/L) and Cr^hi (Cr > 116 μmol/L) groups to exploit whether these gout-associated T cell subsets were functional in gout-targeted kidney dysfunction. The differentiation of B cells was investigated in gout patients.

Results

Our results show that CD 4⁺ T cells, Th2 cells, and Tc2 cells were upregulated, whereas Tc17 cells were downregulated. Tfh cells skewed toward the polarization of Tfh2 cells. Specifically, Tfh2 cells increased, but Tfh1 cells decreased, accompanied with aging for gout patients, suggesting that age might trigger the skewing of Tfh1/Tfh2 cell subsets to influence gout development. Moreover, Tfh2 cells were connected to renal dysfunction as well. No alterations of B cell subsets were observed in patients when compared to controls.

Conclusions

Our data demonstrate age-specific dysfunctions of Tfh1/2 cells in gout occurrence, and Tfh2 cell upregulation is associated with gout-targeted renal dysfunction. However, Tfh2 cells may function in auto-inflammatory gout independent of helping B differentiation, and an in-depth study remains to be conducted.

Effects of Urate-Lowering Therapy on Risk of Hyperlipidemia in Gout by a Population-Based Cohort Study and on In Vitro Hepatic Lipogenesis-Related Gene Expression

Patients with gout are at a higher risk of cardiovascular disease, which is associated with hyperlipidemia. Management of gout in Taiwan is poor, and the association between urate-lowering therapy (ULT) among gout patients and hyperlipidemia is unclear. We conducted a retrospective cohort study using data from the Longitudinal Health Insurance Database (LHID) of Taiwan on new-onset gout patients and a comparison cohort without gout. A Cox proportional hazards model was used to analyze differences in the risk of hyperlipidemia between patients with and without gout after considering related comorbidities. We also examined the ULT medications on the hepatic expression of lipogenesis-related genes. After adjusting for potential confounders, the case group (44,413 patients) was found to have a higher risk of hyperlipidemia than the control cohort (177,652 patients) [adjusted hazards ratio (aHR) = 2.55]. Gout patients without antigout treatment had significantly higher risk of hyperlipidemia than the control cohort (aHR = 3.10). Among gout patients receiving ULT, except those receiving probenecid (aHR = 0.80), all had significantly lower risk of hyperlipidemia than gout patients without ULT (all aHR < 0.90). Using real-time polymerase chain reaction, we found that most of the antigout drugs decreased the expression of hepatic genes related to lipogenesis in differentiated HepaRG cells. These data indicate that these antigout drugs reduce hyperlipidemia in gout patients, partly via the reduction in expression of lipogenesis-related genes, leading to improved blood lipid profiles. We provide evidence of the strong association between gout and hyperlipidemia and highlight the need for appropriate treatment guidelines.

Particulate matter (PM10) as a newly identified environmental risk factor for acute gout flares: A time-series study

OBJECTIVES

This study aimed to investigate the effect of short-term exposure to ambient particulate matter less than 10μm in diameter (PM₁₀) on occurrence of acute gout flares in the general population and identify susceptible groups accordingly.

METHODS

The data of emergency department (ED) cases with acute gout flare in Incheon city, Korea between January 1st 2008 and December 31st 2015 were collected from the National Health Insurance Service claims data. The levels of PM₁₀ and meterological measurements were provided by the Ministry of Environment and the National Meterological Office, respectively. To estimate the risk of daily ED visits due to acute gout flare, these time-series data set were analyzed using generalized additive models with Poisson distribution, including daily average PM₁₀ level, temperature, relative humidity, day of the week, national holiday, season, and date.

RESULTS

The risk of daily ED visits for acute gout flares per interquartile range increment of the average daily PM₁₀ levels significantly increased in the cumulative lag 0-7 model (relative risk, 1.018; 95% confidence interval, 1.008-1.027, P<0.001). In particular, men aged≥40 years and those with a history of diabetes mellitus or gout were significantly at a high risk of acute gout flares by subgroup analysis.

CONCLUSIONS

Our time-series study demonstrated a modest, but significant effect of short-term exposure to PM₁₀ on ED visits for acute gout flares. Ambient PM₁₀ may be a newly identified environmental risk factor for acute gout flares.

Use of the Gout Impact Scale to Evaluate Quality of Life in Chinese Subjects with Gout: A Cross-Sectional Study

BACKGROUND To use a gout-specific quality of life (QoL) tool, the Gout Impact Scale (GIS), to evaluate characteristics of gout affecting QoL in subjects with gout. MATERIAL AND METHODS In this cross-sectional study, 169 individuals with gout completed the 24-item GIS and a general questionnaire regarding gout characteristics. The reliability and validity of the GIS were verified by Cronbach's a and exploratory factor analysis, respectively. The impact of gout characteristics on the QoL of subjects with gout was assessed by stepwise multiple regression analysis. RESULTS The 169 subjects with gout included 149 (88.2%) men and 20 (11.8%) women, of median age 43 years. The reliability of the GIS was appropriate (0.84-0.90), except for Gout Medication Side Effects (0.69) and Unmet Gout Treatment Need (0.59). Exploratory factor analysis showed that construct validity was acceptable, with a cumulative variance contribution rate of 5 common factors of 70.09% and factor loading >0.5 between each pair of items of the GIS. Univariate analysis showed that male sex was positively correlated with Well-being During Attack (p<0.05), and that source of medical expenses, current cigarette use and drinking were significantly correlated with Unmet Gout Treatment Need (p<0.05 each). A family history of gout, gout flares, and attack frequency were significantly correlated with total GIS, Well-being During Attack, and Gout Concern during Attack (p<0.05 each). Multivariate analysis suggested that history of gouty arthritis, acute attack and attack frequency had a considerable impact on QoL (p<0.05 each). CONCLUSIONS The GIS showed acceptable reliability and validity in identifying associations between poor QoL and gout characteristics.

Intraosseous Tophaceous Gout in Hallux Mimicking a Bone Tumor in a Young Patient: A Case Report

CASE

A 17-year-old man experienced night pain in his right hallux. Radiographs revealed a lytic lesion in the proximal phalanx of the right hallux. Magnetic resonance imaging showed a low-signal intensity mass on T1-weighted sequences and isointense-high-signal intensity on T2-weighted sequences. We suspected a benign bone tumor such as osteoid osteoma or a bone cyst and consequently performed biopsy and surgical treatment. The lesion was filled with a whitish chalk-like substance, and pathologic examination revealed tophaceous gout.

CONCLUSIONS

It can be difficult to distinguish intraosseous tophaceous gout from other diseases, including bone tumors, using imaging; hence, pathological examination may be necessary for the diagnosis.

EPS8 regulates an NLRP3 inflammasome-independent caspase-1 activation pathway in monosodium urate crystal-treated RAW264.7 macrophages

Gout is an inflammatory arthritis caused by the phagocytosis of monosodium urate (MSU) crystal deposition in joints. NOD-, LRR-, and pyrin domain-containing 3 (NLRP3) inflammasome-dependent caspase-1 activation is implicated in the processing of interleukin-1β (IL-1β), which is the major effector cytokine in the acute inflammatory response of gout. Mechanisms underlying caspase-1 activation remain unclear. Epidermal growth factor receptor pathway substrate no. 8 (Eps8) is a signal transducer and actin filament organizer that plays a key role in lipopolysaccharide-stimulated phagocytosis in macrophages. Here, RAW264.7 macrophages that have no intact NLRP3 inflammasomes were used to investigate the role of Eps8 in MSU crystal-mediated caspase-1 activation. A kinetic study revealed that the induction of Eps8 expression by MSU crystals occurred before NLRP3, p46/p33 caspase-1, and mature IL-1β in RAW 264.7 cells. In addition, actin cytoskeleton dynamics was required for Eps8 induction and caspase-1 activation in MSU crystal stimulation. Silencing Eps8 had no effect on the basal expression of p46/p33 caspase-1 and NLRP3, but nearly abolished MSU crystal-induced NLRP3 expression and caspase-1 activation. Furthermore, MSU crystals induced Eps8-pro-caspase-1 complex formation and Eps8 formed a stable complex with p33 caspase-1, but not with NLRP3. In summary, our results demonstrated for the first time the importance of Eps8 in MSU crystal-mediated caspase-1 activation without the involvement of NLRP3 inflammasomes.

Variation in methods, results and reporting in electronic health record-based studies evaluating routine care in gout: A systematic review

OBJECTIVE

To perform a systematic review examining the variation in methods, results, reporting and risk of bias in electronic health record (EHR)-based studies evaluating management of a common musculoskeletal disease, gout.

METHODS

Two reviewers systematically searched MEDLINE, Scopus, Web of Science, CINAHL, PubMed, EMBASE and Google Scholar for all EHR-based studies published by February 2019 investigating gout pharmacological treatment. Information was extracted on study design, eligibility criteria, definitions, medication usage, effectiveness and safety data, comprehensiveness of reporting (RECORD), and Cochrane risk of bias (registered PROSPERO CRD42017065195).

RESULTS

We screened 5,603 titles/abstracts, 613 full-texts and selected 75 studies including 1.9M gout patients. Gout diagnosis was defined in 26 ways across the studies, most commonly using a single diagnostic code (n = 31, 41.3%). 48.4% did not specify a disease-free period before 'incident' diagnosis. Medication use was suboptimal and varied with disease definition while results regarding effectiveness and safety were broadly similar across studies despite variability in inclusion criteria. Comprehensiveness of reporting was variable, ranging from 73% (55/75) appropriately discussing the limitations of EHR data use, to 5% (4/75) reporting on key data cleaning steps. Risk of bias was generally low.

CONCLUSION

The wide variation in case definitions and medication-related analysis among EHR-based studies has implications for reported medication use. This is amplified by variable reporting comprehensiveness and the limited consideration of EHR-relevant biases (e.g. data adequacy) in study assessment tools. We recommend accounting for these biases and performing a sensitivity analysis on case definitions, and suggest changes to assessment tools to foster this.

Association of gout and colorectal cancer in Taiwan: a nationwide population-based cohort study

OBJECTIVES

This study aimed to determine colorectal cancer (CRC) risks among patients with gout through a follow-up study on a nationwide population-based cohort that included patients with gout and the general population in Taiwan.

PARTICIPANT

From the Taiwan National Health Insurance Research Database, we identified 28 061 patients who were newly diagnosed with gout between 2000 and 2010 as the study cohort. We randomly selected 84 248 subjects matching in gender, age and baseline year as comparison cohort. The cohorts were followed up until CRC occurrence, withdrawal from the system of National Health Insurance, or Dec. 31, 2013.

PRIMARY AND SECONDARY OUTCOME MEASURES

Cumulative incidences and incidence rate ratios (IRRs) of CRC between two cohorts were examined. The Cox proportional hazards model was used to evaluate risk factors associated with CRC development.

RESULTS

During the 13-year follow-up, the incidence rate of CRC development in the gout cohort reached 2.44 per 1000 person-years, which was higher than the 2.13 per 1000 person-years in the control cohort (IRR=1.15; 95% CI 1.04 to 1.26). After adjusting for age, gender, urbanisation status and comorbidities, including hypertension, diabetes and hyperlipidaemia, gout showed no significant association with increased risk of CRC occurrence (adjusted HR=1.03; 95% CI 0.93 to 1.14).

CONCLUSIONS

Similar risks of CRC incidence were observed in patients with and without gout in Taiwan. Allopurinol and colchicine are commonly used as urate-lowering drug and anti-inflammation medication in Taiwan and had been shown to reduce the risk of CRC incidence. Thus, further pharmaco-epidemiological studies should be carried out to specifically assess the role of allopurinol in the relationship between gout and CRC.

Bone mineral density and serum osteocalcin levels in patients with gout

Objective: The objective of the study is to evaluate the relation of gout with osteoporosis and serum osteocalcin (OC) levels. Material and methods: Seventy-five patients diagnosed with gout and 55 controls were included in the study. Comorbid conditions and drugs associated with osteoporosis were excluded. The T and Z scores from lumbar spine (L2-L4) and femur (neck, ward, trochanter, total) were determined by dual-energy X-ray absorptiometry (DXA). OC levels were measured by enzyme-linked immunosorbent assay. Results: Osteoporosis according to T scores of lumbar vertebrae L2-L4 was found to be significantly higher in patients with gout compared to the control group (p = 0.02). Lumbar spine T-score was -1.6 in gout group and -1.0 in controls. OC level was 7.9 ng/mL in the gout group and 18.9 ng/mL in the control group. There was a significant difference (p < 0.001). In addition, mean OC level was 12.4 ± 6.9 ng/mL in the patients diagnosed with osteoporosis and 17.2 ± 10.6 ng/mL in the patients that were classified as normal and a significant difference was established between the two groups (p = 0.03). A significant negative correlation was found between OC level and body mass index, age, and age at first attack. Similarly, femoral T-score established a negative correlation with parathyroid hormone, age, age at first attack, and allopurinol dose. Conclusion: Serum OC level can be a useful marker in the assessment of bone turnover and clinicians should keep osteoporosis in mind in gout patients.

Genome-wide association study revealed novel loci which aggravate asymptomatic hyperuricaemia into gout

Objective

The first ever genome-wide association study (GWAS) of clinically defined gout cases and asymptomatic hyperuricaemia (AHUA) controls was performed to identify novel gout loci that aggravate AHUA into gout.

Methods

We carried out a GWAS of 945 clinically defined gout cases and 1003 AHUA controls followed by 2 replication studies. In total, 2860 gout cases and 3149 AHUA controls (all Japanese men) were analysed. We also compared the ORs for each locus in the present GWAS (gout vs AHUA) with those in the previous GWAS (gout vs normouricaemia).

Results

This new approach enabled us to identify two novel gout loci (rs7927466 of CNTN5 and rs9952962 of MIR302F) and one suggestive locus (rs12980365 of ZNF724) at the genome-wide significance level (p<5.0×10^–8). The present study also identified the loci of ABCG2, ALDH2 and SLC2A9. One of them, rs671 of ALDH2, was identified as a gout locus by GWAS for the first time. Comparing ORs for each locus in the present versus the previous GWAS revealed three ‘gout vs AHUA GWAS’-specific loci (CNTN5, MIR302F and ZNF724) to be clearly associated with mechanisms of gout development which distinctly differ from the known gout risk loci that basically elevate serum uric acid level.

Conclusions

This meta-analysis is the first to reveal the loci associated with crystal-induced inflammation, the last step in gout development that aggravates AHUA into gout. Our findings should help to elucidate the molecular mechanisms of gout development and assist the prevention of gout attacks in high-risk AHUA individuals.

The Curve of Optimal Sample Size (COSS): A Graphical Representation of the Optimal Sample Size from a Value of Information Analysis

Value of information (VOI) analysis quantifies the opportunity cost associated with decision uncertainty, and thus informs the value of collecting further information to avoid this cost. VOI can inform study design, optimal sample size selection, and research prioritization. Recent methodological advances have reduced the computational burden of conducting VOI analysis and have made it easier to evaluate the expected value of sample information, the expected net benefit of sampling, and the optimal sample size of a study design ([Formula: see text]). The volume of VOI analyses being published is increasing, and there is now a need for VOI studies to conduct sensitivity analyses on VOI-specific parameters. In this practical application, we introduce the curve of optimal sample size (COSS), which is a graphical representation of [Formula: see text] over a range of willingness-to-pay thresholds and VOI parameters (example data and R code are provided). In a single figure, the COSS presents summary data for decision makers to determine the sample size that optimizes research funding given their operating characteristics. The COSS also presents variation in the optimal sample size given variability or uncertainty in VOI parameters. The COSS represents an efficient and additional approach for summarizing results from a VOI analysis.

Calculating incidence rates and prevalence proportions: not as simple as it seems

BACKGROUND

Incidence rates and prevalence proportions are commonly used to express the populations health status. Since there are several methods used to calculate these epidemiological measures, good comparison between studies and countries is difficult. This study investigates the impact of different operational definitions of numerators and denominators on incidence rates and prevalence proportions.

METHODS

Data from routine electronic health records of general practices contributing to NIVEL Primary Care Database was used. Incidence rates were calculated using different denominators (person-years at-risk, person-years and midterm population). Three different prevalence proportions were determined: 1 year period prevalence proportions, point-prevalence proportions and contact prevalence proportions.

RESULTS

One year period prevalence proportions were substantially higher than point-prevalence (58.3 - 206.6%) for long-lasting diseases, and one year period prevalence proportions were higher than contact prevalence proportions (26.2 - 79.7%). For incidence rates, the use of different denominators resulted in small differences between the different calculation methods (-1.3 - 14.8%). Using person-years at-risk or a midterm population resulted in higher rates compared to using person-years.

CONCLUSIONS

All different operational definitions affect incidence rates and prevalence proportions to some extent. Therefore, it is important that the terminology and methodology is well described by sources reporting these epidemiological measures. When comparing incidence rates and prevalence proportions from different sources, it is important to be aware of the operational definitions applied and their impact.

Hyperuricemia in Children and Adolescents: Present Knowledge and Future Directions

Recent evidence suggests that hyperuricemia is an important condition in children and adolescents, particularly in association with noncommunicable diseases. This review aims to summarize our current understanding of this condition in pediatric patients. An analysis of serum uric acid reference values in a healthy population indicates that they increase gradually with age until adolescence, with differences between the sexes arising at about 12 years of age. This information should be taken into consideration when defining hyperuricemia in studies. Gout is extremely rare in children and adolescents, and most patients with gout have an underlying disease. The major causes of hyperuricemia are chronic conditions, including Down syndrome, metabolic or genetic disease, and congenital heart disease, and acute conditions, including gastroenteritis, bronchial asthma (hypoxia), malignant disorders, and drug side effects. The mechanisms underlying the associations between these diseases and hyperuricemia are discussed, together with recent genetic information. Obesity is a major cause of hyperuricemia in otherwise healthy children and adolescents. Obesity is often accompanied by metabolic syndrome; hyperuricemia in obese children and adolescents is associated with the components of metabolic syndrome and noncommunicable diseases, including hypertension, insulin resistance, dyslipidemia, and chronic kidney disease. Finally, strategies for the treatment of hyperuricemia, including lifestyle intervention and drug administration, are presented.

Differential risk group of developing stroke among older women with gouty arthritis: A latent transition analysis

OBJECTIVE

Gout-related comorbidities are intricate and its clinical features may demonstrate sex difference; however, few studies have evaluated the links between comorbidities and gout in a female population. The objectives of this study were to compare the aggregation and transitive trajectories of comorbidities of gout, and their consequences in female and male gout populations.

METHODS

A prospective cohort study was conducted using data from the Taiwan National Health Insurance Research Database. A female and male gout population were followed up from 2000 to 2009 to identify the comorbidities of cardiovascular disease, hyperlipidemia, hypertension, diabetes mellitus (DM) and chronic kidney disease. The cumulative incidence of stroke from 2000 to 2010 was examined. A latent trajectory analysis was used to determine the transitive trajectories of the comorbidities of gout.

RESULTS

Both female and male patients with gout had five risk cluster transition (CT) phenotypes of comorbidities within 10-year follow-up: CT1 and CT2, with various persistent comorbidities; CT3, with few persistent comorbidities; and CT4 and CT5, with transfer to cluster 1 from other clusters. The female participants in CT2 predominantly experienced DM and were associated with significantly increased risk of developing stroke.

CONCLUSION

Diabetes is a notable risk factor for the development of stroke in female patients with gout. Early assessment and management for the comorbidities of gout, particularly in DM, would effectively reduce future stroke risk in female gout population.

A meta-analysis of the association between gout, serum uric acid level, and obstructive sleep apnea

Previous epidemiological investigations have evaluated the association between gout, serum uric acid levels, and obstructive sleep apnea syndrome (OSAS), but with inconsistent results. We conducted this meta-analysis aiming at providing clear evidence about whether OSAS patients have higher serum uric acid levels and more susceptible to gout. Relevant studies were identified via electronic databases from inception to December 17, 2018. Study selection was conducted according to predesigned eligibility criteria, and two authors independently extracted data from included studies. The hazard ratio (HR) and weighted mean difference (WMD) and their corresponding 95% confidence interval (CI) were derived using random-effects models. We conducted meta-, heterogeneity, publication bias, sensitivity, and subgroup analyses. Eighteen studies, involving a total of 157,607 individuals (32,395 with OSAS, 125,212 without OSAS) and 12,262 gout cases, were included. Results show that serum uric acid levels are elevated in patients with OSAS (WMD = 52.25, 95% CI 36.16-64.33); OSAS did not reach statistical significance as a predictor of gout (but there was a trend, HR = 1.25, 95% CI 0.91-1.70) and that the association between OSAS and serum uric acid was quite robust. OSAS may be a potential risk factor for hyperuricemia and the development of gout and thus, effective OSAS therapy may present as a valuable preventive measure against gout. Still, it is vital to undertake clinical studies with better designing to corroborate these associations and shed new light on it.

Integrative Genome-Wide Association Studies of eQTL and GWAS Data for Gout Disease Susceptibility

There is a paucity of genome-wide association study on Han Chinese gout patients. We performed a genome-wide association meta-analysis on two Taiwanese cohorts consisting of 758 gout cases and 14166 controls of Han Chinese ancestry. All the participants were recruited from the Taiwan Biobank. For pathway analysis, we applied ICSNPathway (Identify candidate Causal SNPs and Pathways) analysis, and to investigate whether expression-associated genetic variants contribute to gout susceptibility, we systematically integrated lymphoblastoid expression quantitative trait loci (eQTL) and genome-wide association data of gout using Sherlock, a Bayesian statistical frame-work. In the meta-analysis, we found 4 SNPs that reached genome-wide statistical significance (P < 5.0 × 10⁻⁸). These SNPs are in or close to ABCG2, PKD2 and NUDT9 gene on chromosome 4. ICSNPathway analysis identified rs2231142 as the candidate causal SNP, and ABCG2 as the candidate gene. Sherlcok analysis identified three genes, which were significantly associated with the risk of gout (PKD2, NUTD9, and NAP1L5). To conclude, we reported novel susceptible loci for gout that has not been previously addressed in the literature.

Joint Clinical Consensus Statement of the American College of Foot and Ankle Surgeons® and the American Association of Nurse Practitioners®: Etiology, Diagnosis, and Treatment Consensus for Gouty Arthritis of the Foot and Ankle

Gout is a condition that commonly affects the foot and ankle, and practitioners who treat these structures should be aware of the methods to diagnose and treat this form of arthritis. Practitioners also need to recognize extra-articular manifestations of the disease. Although the acutely red, hot, swollen joint is a common presentation, chronic tophaceous gout can be associated with pain, nodule formation, and cutaneous compromise. Since the underlying causes that lead to excessive monosodium urate deposition may be treatable, early and accurate diagnosis can be very beneficial and may even prevent articular degeneration.

Long-term prognostic impact of hyperuricemia in community

The debate whether an elevated level of serum uric acid (SUA) is an independent marker of cardiovascular risk is still going on. We examined morbidity and mortality related to SUA and hyperuricemia in a well-characterized population with very long follow-up. Study included 4696 participants (aged 30-59 years at baseline) of the coronary heart disease (CHD) Study of the Finnish Mobile Clinic Health Examination Survey. Adjusted hazard ratios (HRs) of hyperuricemia (defined as ≥360 µmol/l and ≥420 µmol/l) and SUA quintiles for mortality and adverse cardiovascular outcomes are reported. During the mean follow up of 30.6 years there were 2723 deaths, 887 deaths for CHD of which 340 were classified as sudden cardiac deaths, 1642 hospitalizations due to CHD and 798 hospitalizations due to congestive heart failure. After adjusting to baseline risk factors and presence of cardiovascular diseases as well as the use of diuretics there were no significant differences in the risk of any of the outcomes when analyzed either according to quintiles of SUA or using a cut-off point SUA ≥360 µmol/l for hyperuricemia. Only a rare finding of hyperuricemia SUA ≥420 µmol/l among women (n = 17, 0.9%) was independently associated with significantly higher risk of mortality (adjusted HR: 2.59, 95% CI: 1.54-4.34) and a combination end-point of major adverse cardiac events (MACEs) (HR: 2.69; 95% CI: 1.56-4.66). SUA was not an independent indicator of morbidity and mortality, with the exception of particularly high levels of SUA among women.

The risk of clinically diagnosed gout by serum urate levels: results from 30 years follow-up of the Malmö Preventive Project cohort in southern Sweden

Background

Hyperuricemia (HU) is in the causal pathway for developing clinical gout. There are few population-based assessments of the absolute and relative risk of clinically diagnosed incident gout in subjects with HU. We aimed to explore the long-term risk of developing incident gout among asymptomatic adults with different levels of serum urate (SU).

Methods

Malmö Preventive Project was a population-based screening program for cardiovascular risk factors, alcohol abuse, and breast cancer in Malmö, Sweden. The study population was screened between 1974 and 1992. At baseline, subjects were assessed with a questionnaire, physical examination, and laboratory tests. Follow-up ended at first gout diagnosis, death, moving from area, or December 31, 2014. Incident gout (using ICD10 codes) was diagnosed based on national registers for specialized inpatient and outpatient care, and from 1998 onward in the Skåne Healthcare Register including primary healthcare. Incidence rates, absolute risk, hazard ratios (HRs) and potentially associated factors were analyzed by baseline SU levels, i.e. normal levels (≤ 360 μmol/L); 361–405 (levels below tissue solubility of SU), and > 405 (HU), overall, and by sex.

Results

Overall, 1275 individuals [3.8%; 1014 men (4.5%) and 261 women (2.4%)] of the 33,346 study participants (mean age: 45.7 (SD: 7.4), 67% men), developed incident gout during follow-up (mean 28.2 years). Of those with HU, 14.7% of men and 19.5% of women developed gout. Compared to subjects in the lowest SU category, the age-adjusted HR in men increased from 2.7 to 6.4, and in women from 4.4 to 13.1 with increasing baseline SU category, and with a statistically significant interaction of sex (p < 0.001). Body mass index, estimated glomerular filtration rate (negative), triglycerides, alcohol risk behavior (only in men), and comorbidities such as hypertension, cardiovascular disease, and diabetes were strongly associated with SU at baseline in both sexes.

Conclusions

The absolute risk for developing clinically diagnosed gout over 30 years in middle-aged subjects was 3.8%, and increased progressively in both men and women in relation to baseline SU. This risk increase was significantly higher in women than in men, whereas the associations between baseline risk markers and SU levels were similar in both sexes.

Metabolism and disposition of lesinurad, a uric acid reabsorption inhibitor, in humans

The objectives of this study were to determine the absolute bioavailability of lesinurad and to characterized its disposition in humans. The oral bioavailability assessment was performed using a clinical design of simultaneous dosing of a therapeutic oral dose of lesinurad with an intravenous infusion of [¹⁴C]lesinurad microdose. The bioavailability of lesinurad was determined to be 100%. The disposition of lesinurad in humans involves hepatic oxidation and renal elimination following administration of oral [¹⁴C]lesinurad dose. Metabolism of lesinurad occurred post-systemically with low circulating levels of metabolites <3% of total radioactivity as 74.2% of total radioactivity was attributed to lesinurad. In vitro metabolism studies identified CYP2C9 as the predominant isoform, and summation of metabolites indicated that it was responsible for ∼50% of metabolism.

Uric acid and cardiovascular disease

Uric acid (UA) is an end product of purine metabolism in humans and great apes. UA acts as an antioxidant and it accounts for 50% of the total antioxidant capacity of biological fluids in humans. When present in cytoplasm of the cells or in acidic/hydrophobic milieu in atherosclerotic plaques, UA converts into a pro-oxidant agent and promotes oxidative stress and through this mechanism participates in the pathophysiology of human disease including cardiovascular disease (CVD). Most epidemiological studies but not all of them suggested the existence of an association between elevated serum UA level and CVD, including coronary heart disease (CHD), stroke, congestive heart failure, arterial hypertension and atrial fibrillation as well as an increased risk for mortality due to CVD in general population and subjects with confirmed CHD. Evidence available also suggests an association between elevated UA and traditional cardiovascular risk factors, metabolic syndrome, insulin resistance, obesity, non-alcoholic fatty liver disease and chronic kidney disease. Experimental and clinical studies have evidenced several mechanisms through which elevated UA level exerts deleterious effects on cardiovascular health including increased oxidative stress, reduced availability of nitric oxide and endothelial dysfunction, promotion of local and systemic inflammation, vasoconstriction and proliferation of vascular smooth muscle cells, insulin resistance and metabolic dysregulation. Although the causality in the relationship between UA and CVD remains unproven, UA may be pathogenic and participate in the pathophysiology of CVD by serving as a bridging mechanism mediating (enabling) or potentiating the deleterious effects of cardiovascular risk factors on vascular tissue and myocardium.

Metabolism and Disposition of Verinurad, a Uric Acid Reabsorption Inhibitor, in Humans

Verinurad (RDEA3170) is a second generation selective uric acid reabsorption inhibitor for the treatment of gout and asymptomatic hyperuricemia. Following a single oral solution of 10-mg dose of [¹⁴C]verinurad (500 μCi), verinurad was rapidly absorbed with a median time to occurrence of maximum observed concentration (T_max) of 0.5 hours and terminal half-life of 15 hours. In plasma, verinurad constituted 21% of total radioactivity. Recovery of radioactivity in urine and feces was 97.1%. Unchanged verinurad was the predominant component in the feces (29.9%), whereas levels were low in the urine (1.2% excreted). Acylglucuronide metabolites M1 (direct glucuronidation) and M8 (glucuronidation of N-oxide) were formed rapidly after absorption of verinurad with terminal half-life values of approximately 13 and 18 hours, respectively. M1 and M8 constituted 32% and 31% of total radioactivity in plasma and were equimolar to verinurad on the basis of AUC ratios. M1 and M8 formed in the liver were biliary cleared with complete hydrolysis in the GI tract, as metabolites were not detected in the feces and/or efflux across the sinusoidal membrane; M1 and M8 accounted for 29.2% and 32.5% of the radioactive dose in urine, respectively. In vitro studies demonstrated that CYP3A4 mediated the formation of the N-oxide metabolite (M4), which was further metabolized by glucuronyl transferases (UGTs) to form M8, as M4 was absent in plasma and only trace levels were present in the urine. Several UGTs mediated the formation of M1, which could also be further metabolized by CYP2C8. Overall, the major clearance route of verinurad is metabolism via UGTs and CYP3A4 and CYP2C8.