Sodium-Glucose Cotransporter-2 Inhibitors vs Sulfonylureas for Gout Prevention Among Patients With Type 2 Diabetes Receiving Metformin

Importance

Sodium-glucose cotransporter type 2 inhibitors (SGLT2i) are a revolutionary treatment for type 2 diabetes (T2D) with cardiovascular, kidney, and serum urate-lowering benefits.

Objective

To compare risk of incident gout and rate of recurrent flares between patients with T2D initiating SGLT2i vs sulfonylurea, most common second-line glucose-lowering therapy, when added to metformin monotherapy.

Design, Setting, and Participants

This sequential, propensity score-matched, new-user comparative effectiveness study using target trial emulation framework included adults with T2D receiving metformin monotherapy in a Canadian general population database from January 1, 2014, to June 30, 2022.

Exposures

Initiation of SGLT2i vs sulfonylurea.

Main Outcomes and Measures

The primary outcome was incident gout diagnosis, ascertained by emergency department (ED), hospital, outpatient, and medication dispensing records. Secondary outcomes were gout-primary hospitalizations and ED visits and major adverse cardiovascular events (MACE), as well as recurrent flare rates among prevalent gout patients. Heart failure (HF) hospitalization was assessed as positive control outcome and osteoarthritis encounters as negative control. For target trial emulations, we used Cox proportional hazards and Poisson regressions with 1:1 propensity score matching (primary analysis) and overlap weighting (sensitivity analysis). The analysis was conducted from September to December, 2023.

Results

Among 34 604 propensity score matched adults with T2D initiating SGLT2i or sulfonylurea (20 816 [60%] male, mean [SD] age, 60 [12.4] years), incidence of gout was lower among SGLT2i initiators (4.27 events per 1000 person-years) than sulfonylurea initiators (6.91 events per 1000 person-years), with a hazard ratio (HR) of 0.62 (95% CI, 0.48-0.80) and a rate difference (RD) of -2.64 (95% CI, -3.99 to -1.29) per 1000 person-years. Associations persisted regardless of sex, age, or baseline diuretic use. SGLT2i use was also associated with fewer recurrent flares among gout patients (rate ratio, 0.67; 95% CI, 0.55-0.82; and RD, -20.9; 95% CI, -31.9 to -10.0 per 1000 person-years). HR and RD for MACE associated with SGLT2i use were 0.87 (95% CI, 0.77-0.98) and -3.58 (95% CI, -6.19 to -0.96) per 1000 person-years. For control outcomes, SGLT2i users had lower risk of HF (HR, 0.53; 95% CI, 0.38-0.76), as expected, with no difference in osteoarthritis (HR, 1.11; 95% CI, 0.94-1.34). Results were similar when applying propensity score overlap weighting.

Conclusions

In this population-based cohort study, the gout and cardiovascular benefits associated with SGLT2i in these target trial emulations may guide selection of glucose-lowering therapy in patients with T2D, at risk for or already with gout.

Biomimetic Integrated Nanozyme for Flare and Recurrence of Gouty Arthritis

Flare and multiple recurrences pose significant challenges in gouty arthritis. Traditional treatments provide temporary relief from inflammation but fail to promptly alleviate patient pain or effectively prevent subsequent recurrences. It should also be noted that both anti-inflammation and metabolism of uric acid are necessary for gouty arthritis, calling for therapeutic systems to achieve these two goals simultaneously. In this study, we propose a biomimetic integrated nanozyme, HMPB-Pt@MM, comprising platinum nanozyme and hollow Prussian blue. It demonstrates anti-inflammatory properties by eliminating reactive oxygen species and reducing infiltration of inflammatory macrophages. Additionally, it rapidly targets inflamed ankles through the camouflage of macrophage membranes. Furthermore, HMPB-Pt@MM exhibits urate oxidase-like capabilities, continuously metabolizing locally elevated uric acid concentrations, ultimately inhibiting multiple recurrences of gouty arthritis. In summary, HMPB-Pt@MM integrates ROS clearance with uric acid metabolism, offering a promising platform for the treatment of gouty arthritis.

Clustering of gout-related comorbidities and their relationship with gout flares: a data-driven cluster analysis of eight comorbidities

OBJECTIVES

To study the aggregation of multiple comorbidities in people with gout and explore differences in prognosis of gout flares among different subgroups.

METHODS

Hierarchical clustering was performed to identify homogeneous subgroups among 2639 people with gout using eight comorbidities. A one-year follow-up of acute gout flares in 463 of these people was conducted; the incidence and the timing of gout flares in each cluster were assessed to explore prognosis of gout flares. Binary logistic regression was applied to assess factors associated with gout flares.

RESULTS

In baseline study, we identified five subgroups (C1-C5). C1 (n = 671, 25%) was characterized by isolated gout with few comorbidities. C2 (n = 258, 10%) were all obese. Almost all people in C3 (n = 335, 13%) had diabetes (99.7%). All people in C4 (n = 938, 36%) had dyslipidemia. C5 (n = 437, 17%) had the highest proportion of cardiovascular disease (CVD, 53%), chronic kidney disease (CKD, 56%), and cancer (7%). In follow-up study, C5 had the highest incidence (71.9%) and earliest onset (median 3 months) of gout flares. C2 had the lowest incidence (52.1%) and the latest onset (median 10 months) of gout flares. The highest relative risk for gout recurrent was seen for C5 (OR = 2.09). Other factors associated with the risk of gout flares were age at diagnosis of gout, duration of gout, presence of tophi, and smoking ≥ 20 cigarettes/day.

CONCLUSIONS

We clustered people with gout into five groups with varying comorbidities. People with CVD, CKD, and cancer had the highest risk of gout flares and should receive comprehensive care.

Clinical characteristics of adolescent-onset gout in Chinese: A hospital-based cross-sectional study

OBJECTIVE

Adolescent-onset gout has a greater impact on the lives and health of patients than adult-onset gout. However, there is a relative lack of clinical information on adolescent-onset gout. Hence, we analyzed a Chinese cohort.

METHODS

We studied clinical features of 9,003 Chinese patients. Gout onset age of 12 - 19 years is defined as adolescent-onset group (AG), 20 - 40 years as early-onset group (EG), and 41 - 64 years as late-onset group (LG). Multivariable regression analysis evaluated factors associated with recurrent flares, serum urate (SU) levels, and underexcretion type in AG.

RESULTS

Compared with EG and LG, the AG had higher SU levels [AG: 9.5 (2.2) mg/dL, EG: 8.6 (2.1) mg/dL, LG: 7.73 (2.0) mg/dL, P < 0.001], higher percentage of positive family history of gout (AG: 41.8 %, EG: 29.6 %, LG: 24.6 %, P < 0.001), underexcretion type (AG: 62.4 %, EG: 62.5 %, LG: 58.8 %, P = 0.04), recurrent flares (AG: 78.1 %, EG: 70.3 %, LG: 68.9 %, P = 0.01). Urate-lowering therapy (ULT) initiated [OR 6.58 (95 % CI 1.35 - 32.00)] and hypercholesterolemia [OR 4.16 (95 % CI 1.28 - 13.53)] were associated with recurrent flares. eGFR was identified to be a significant variable of increasing SU levels [beta -0.24 (95 % CI -0.04 to -0.01)]. Hypertriglyceridemia [OR 0.35 (95 % CI 0.17 - 0.71)] was related to underexcretion type.

CONCLUSION

Adolescent-onset gout patients had clinically distinctive features with higher SU levels, BMI, positive gout family history, underexcretion type and recurrent flares. These specific populations were less likely to achieve ULT target, requiring more clinical attention.

Serum Urate and Recurrent Gout

Importance

Approximately 12 million adults in the US have a history of gout, but whether serum urate levels can help predict recurrence is unclear.

Objective

To assess associations of a single serum urate measurement with subsequent risk of acute gout flares and subsequent risk of hospitalizations for gout among patients in the UK with a history of gout.

Design, Setting, and Participants

This retrospective study included patients with a history of gout identified from the UK between 2006 and 2010 who were followed up through Primary Care Linked Data medical record linkage until 2017 and through the Hospital Episode Statistics database until 2020.

Exposures

Serum urate levels at enrollment.

Main Outcome and Measure

Rate of recurrent acute gout, ascertained by hospitalization, outpatient, and prescription/procedure records, and adjusted rate ratios using negative binomial regressions.

Results

Among 3613 patients with gout (mean age, 60 years; 3104 [86%] men), 1773 gout flares occurred over a mean follow-up of 8.3 years. Of these, 1679 acute gout flares (95%) occurred in people with baseline serum urate greater than or equal to 6 mg/dL and 1731 (98%) occurred in people with baseline serum urate greater than or equal to 5 mg/dL. Rates of acute gout flares per 1000 person-years were 10.6 for participants with baseline urate levels less than 6 mg/dL, 40.1 for levels of 6.0 to 6.9 mg/dL, 82.0 for levels of 7.0 to 7.9 mg/dL, 101.3 for levels of 8.0 to 8.9 mg/dL, 125.3 for urate levels of 9.0 to 9.9 mg/dL, and 132.8 for levels greater than or equal to 10 mg/dL. Rate ratio of flares were 1.0, 3.37, 6.93, 8.67, 10.81, and 11.42, respectively, over 10 years (1.61 [1.54-1.68] per mg/dL). Rates of hospitalization per 1000 person-years during follow-up were 0.18 for those with baseline serum urate less than 6 mg/dL, 0.97 for serum urate of 6.0 to 6.9 mg/dL, 1.8 for serum urate of 7.0 to 7.9 mg/dL, 2.2 for serum urate of 8.0 to 8.9 mg/dL, 6.7 for serum urate of 9.0 to 9.9 mg/dL, and 9.7 for serum urate greater than or equal to 10 mg/dL. Rate ratios of hospitalization for gout, adjusting for age, sex, and race were 1.0, 4.70, 8.94, 10.37, 33.92, and 45.29, respectively (1.87 [1.57-2.23] per mg/dL).

Conclusions and Relevance

In this retrospective study of patients with a history of gout, serum urate levels at baseline were associated with the risk of subsequent gout flares and rates of hospitalization for recurrent gout. These findings support using a baseline serum urate level to assess risk of recurrent gout over nearly 10 years of follow-up.

Metabolomics and Machine Learning Identify Metabolic Differences and Potential Biomarkers for Frequent Versus Infrequent Gout Flares

OBJECTIVE

The objective of this study was to discover differential metabolites and pathways underlying infrequent gout flares (InGF) and frequent gout flares (FrGF) using metabolomics and to establish a predictive model by machine learning (ML) algorithms.

METHODS

Serum samples from a discovery cohort of 163 patients with InGF and 239 patients with FrGF were analyzed by mass spectrometry-based untargeted metabolomics to profile differential metabolites and explore dysregulated metabolic pathways using pathway enrichment analysis and network propagation-based algorithms. ML algorithms were performed to establish a predictive model based on selected metabolites, which was further optimized by a quantitative targeted metabolomics method and validated in an independent validation cohort with 97 participants with InGF and 139 participants with FrGF.

RESULTS

A total of 439 differential metabolites between InGF and FrGF groups were identified. Top dysregulated pathways included carbohydrates, amino acids, bile acids, and nucleotide metabolism. Subnetworks with maximum disturbances in the global metabolic networks featured cross-talk between purine metabolism and caffeine metabolism, as well as interactions among pathways involving primary bile acid biosynthesis, taurine and hypotaurine metabolism, alanine, aspartate, and glutamate metabolism, suggesting epigenetic modifications and gut microbiome in metabolic alterations underlying InGF and FrGF. Potential metabolite biomarkers were identified using ML-based multivariable selection and further validated by targeted metabolomics. Area under receiver operating characteristics curve for differentiating InGF and FrGF achieved 0.88 and 0.67 for the discovery and validation cohorts, respectively.

CONCLUSION

Systematic metabolic alterations underlie InGF and FrGF, and distinct profiles are associated with differences in gout flare frequencies. Predictive modeling based on selected metabolites from metabolomics can differentiate InGF and FrGF.

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.

Risk of Venous Thromboembolism With Gout Flares

OBJECTIVE

Previous studies demonstrated that the risk of venous thromboembolism (VTE) is increased in patients with gout, but not whether there was a temporal association between gout flare and VTE. This study was undertaken to evaluate potential temporal associations between gout flare and VTE.

METHODS

Data were obtained from electronic primary-care records from the UK's Clinical Practice Research Datalink, which links data from hospitalization and mortality registers. Using self-controlled case series analysis adjusted for season and age, we evaluated the temporal association between gout flare and VTE. The 90 days after primary-care consultation or hospitalization for gout flare was designated the exposed period. This was divided into three 30-day intervals. The baseline period was up to 2 years before the start of and up to 2 years after the end of the exposed period. The association between gout flare and VTE was measured using adjusted incidence rate ratios (IRRs) with 95% confidence intervals (95% CIs).

RESULTS

In total, 314 patients met the inclusion criteria (age ≥18 years, incident gout, no presence of VTE or use of a primary-care anticoagulant prescription before the start of the pre-exposure period). Among the 314 patients, VTE incidence was significantly higher in the exposed period than in the baseline period (adjusted IRR 1.83, 95% CI 1.30-2.59). The adjusted IRR of VTE during the first 30 days after gout flare was 2.31 (95% CI 1.39-3.82) relative to the baseline period. No increase in the adjusted IRRs was observed in days 31-60 (adjusted IRR 1.49, 95% CI 0.79-2.81) and days 61-90 (adjusted IRR 1.67, 95% CI 0.91-3.06) relative to baseline. Results were consistent across sensitivity analyses.

CONCLUSION

Among patients with gout, there was a transient increase in the rate of VTE within 30 days after primary-care consultation or hospitalization for gout flare.

Gout Flares and Mortality After Sodium-Glucose Cotransporter-2 Inhibitor Treatment for Gout and Type 2 Diabetes

Importance

Recurrent flares are the hallmark of clinical manifestation of gout. Sodium-glucose cotransporter-2 inhibitors (SGLT2i) have been associated with a lower risk of incident gout; however, their association with recurrent flares is unknown.

Objective

To examine the association of SGLT2i vs active comparators (ie, glucagonlike peptide-1 receptor agonists [GLP-1 RA] or dipeptidyl peptidase-4 inhibitors [DPP-4i]) with the risk of recurrent gout flares and all-cause mortality among patients with gout and type 2 diabetes.

Design, Setting, and Participants

This population-based retrospective cohort study was performed from January 1, 2013, to March 31, 2022, using a UK primary care database. Participants included patients with gout and type 2 diabetes with visits to their general practitioners.

Exposures

Initiation of treatment with SGLT2i or active comparators.

Main Outcomes and Measures

The primary outcome was the number of recurrent gout flares ascertained using recorded codes and prescription records. Secondary outcomes were the first recurrent gout flare and all-cause mortality. The association of SGLT2i compared with active comparators for the risk of recurrent flares, the first recurrent flare, and all-cause mortality was assessed using Poisson regression or the Cox proportional hazards model with propensity score overlap weighting.

Results

Of a total of 5931 patients included in the analysis (mean [SD] age, 66.0 [11.6] years; 4604 [77.6%] men), 1548 initiated SGLT2i treatment and 4383 initiated treatment with active comparators during the study period. The relative rate of the recurrent flares with SGLT2i vs active comparators was 0.79 (95% CI, 0.65-0.97). Similar results were observed in the association of SGLT2i with the rate of recurrent flares when compared with DPP-4i or GLP-1 RA. For the first recurrent flare for SGLT2i vs active comparators, rate difference was -8.8 (95% CI, -17.2 to -0.4) per 1000 person-years and the hazard ratio was 0.81 (95% CI, 0.65-0.98). All-cause mortality per 1000 person-years was 18.8 for SGLT2i and 24.9 for active comparators, with rate difference of -6.1 (95% CI, -10.6 to -1.6) per 1000 person-years and hazard ratio of 0.71 (95% CI, 0.52-0.97).

Conclusions and Relevance

The findings of this cohort study suggest that SGLT2i were associated with a lower risk of recurrent gout flares and mortality than their active comparators in patients with gout and type 2 diabetes. These findings further suggest that SGLT2i could help reduce the burden of recurrent gout flares and could also narrow the mortality gap between patients with gout and the general population.

Comparative Effectiveness of Sodium-Glucose Cotransporter-2 Inhibitors for Recurrent Gout Flares and Gout-Primary Emergency Department Visits and Hospitalizations : A General Population Cohort Study

BACKGROUND

Sodium-glucose cotransporter-2 inhibitors (SGLT2is) decrease serum urate levels, but whether this translates into prevention of recurrent flares among patients with gout and gout-primary emergency department (ED) visits or hospitalizations is unknown.

OBJECTIVE

To compare gout flares and cardiovascular events among patients with gout initiating SGLT2is versus dipeptidyl peptidase 4 inhibitors (DPP-4is), another second-line glucose-lowering agent not associated with serum urate levels or cardiovascular risk.

DESIGN

Propensity score-matched, new-user cohort study.

SETTING

General population database from 1 January 2014 to 30 June 2022.

PARTICIPANTS

Patients with gout and type 2 diabetes.

MEASUREMENTS

The primary outcome was recurrent gout flare counts ascertained by ED, hospitalization, outpatient, and medication dispensing records. Secondary outcomes included myocardial infarction and stroke; genital infection (positive control) and osteoarthritis encounter (negative control) were also assessed. Poisson and Cox proportional hazards regressions were used with 1:1 propensity score matching (primary analysis) and overlap weighting (sensitivity analysis).

RESULTS

After propensity score matching, the flare rate was lower among SGLT2i initiators than DPP-4i initiators (52.4 and 79.7 events per 1000 person-years, respectively), with a rate ratio (RR) of 0.66 (95% CI, 0.57 to 0.75) and a rate difference (RD) of -27.4 (CI, -36.0 to -18.7) per 1000 person-years. The corresponding RR and RD for gout-primary ED visits and hospitalizations were 0.52 (CI, 0.32 to 0.84) and -3.4 (CI, -5.8 to -0.9) per 1000 person-years, respectively. The corresponding hazard ratio (HR) and RD for myocardial infarction were 0.69 (CI, 0.54 to 0.88) and -7.6 (CI, -12.4 to -2.8) per 1000 person-years; the HR for stroke was 0.81 (CI, 0.62 to 1.05). Those who initiated SGLT2is showed higher risk for genital infection (HR, 2.15 [CI, 1.39 to 3.30]) and no altered risk for osteoarthritis encounter (HR, 1.07 [CI, 0.95 to 1.20]). Results were similar when propensity score overlap weighting was applied.

LIMITATION

Participants had concurrent type 2 diabetes.

CONCLUSION

Among patients with gout, SGLT2is may reduce recurrent flares and gout-primary ED visits and hospitalizations and may provide cardiovascular benefits.

PRIMARY FUNDING SOURCE

National Institute of Arthritis and Musculoskeletal and Skin Diseases.

Elevated serum CA72-4 predicts gout flares during urate lowering therapy initiation: a prospective cohort study

OBJECTIVE

Gout flares during urate-lowering therapy (ULT) initiation are common, but predictors of these flares are poorly understood. The aim of this study was to determine whether serum CA72-4 is an independent predictor for gout flares during ULT initiation.

METHODS

A prospective cohort study was conducted between March 2021 and January 2022. Men with gout, at least one gout flare in the past year, and at least three serum CA72-4 measurements in the previous six months were enrolled. Participants were grouped according to their highest recorded serum CA72-4 levels (above or within the normal range). All participants took oral febuxostat 20 mg daily without flare prophylaxis therapy, and attended face-to-face visits every four weeks until 24 weeks. The incidence of gout flare was compared between the two groups. Backward stepwise logistic regression analyses were used to identify risk factors associated with flares. Receiver operating characteristic curve analysis was used to evaluate prediction efficacy.

RESULTS

A total of 193 completed the study (79 with high CA72-4; 114 with normal CA72-4). The cumulative incidence of at least one gout flare was 48.1% (62.1% in the high CA72-4 group, 38.4% in the normal CA72-4 group, P = 0.001), and recurrent (≥2) flares was 33.0% (47.1% in the high CA72-4 group, 23.2% in the normal CA72-4, P < 0.001). High CA72-4, disease duration, intra-articular tophus size, glucose, high-density lipoprotein-cholesterol and ESR were independent risk factors for gout flares. Serum CA72-4 alone predicted recurrent flares with an area under the curve of 0.63 (95% CI = 0.54, 0.71), and 0.78 (95% CI = 0.71, 0.85) when combined with other independent variables.

CONCLUSION

High serum CA72-4 predicts the risk of gout flares during ULT initiation.

TRIAL REGISTRATION

ChiCTR; https://www.chictr.org.cn/; ChiCTR2100043573.

Ultrasonography in the prediction of gout flares: a 12-month prospective observational study

OBJECTIVES

To evaluate whether US findings indicating MSU deposits and US-detected inflammation (i.e. power Doppler signal) predict gout flares over 12 months.

METHODS

Gout patients on urate-lowering therapy for at least the preceding 6 months were enrolled consecutively in this 12-month prospective, observational, single-centre study. A nested case-control analysis was performed. Cases were participants with at least one flare in the follow-up period, while controls did not self-report any gout flare. The US assessment included elbows, wrists, second MCP joints, knees, ankles, and first MTP joints. The US findings indicating MSU deposits [i.e. aggregates, double contour (DC) sign and tophi] were identified as present/absent according to the Outcome Measure in Rheumatology definitions. Power Doppler signal was scored semiquantitatively. Summated scores were calculated for each US finding.

RESULTS

Eighty-one gout participants were enrolled, and 71 completed the study. Thirty (42.3%) of 71 participants experienced at least one flare over 12 months, with a median of 2.0 flares. Cases had a greater US burden of MSU deposits (6.7 ± 4.7 vs 2.9 ± 2.6, P = 0.01) and power Doppler signal (3.73 ± 3.53 vs 0.82 ± 1.44, P < 0.01) than controls, at baseline. The baseline US scores indicating MSU deposits and US-detected inflammation were significantly associated with the occurrence (total MSU score, adjusted odds ratio:1.75, 95% CI: 1.26, 2.43; power Doppler score, adjusted odds ratio: 1.63, 95% CI: 1.12, 2.40) and the number (total MSU score, adjusted incidence risk ratio: 1.17, 95% CI: 1.08, 1.26; power Doppler score, adjusted incidence risk ratio: 1.29, 95% CI: 1.19, 1.40) of flares over 12 months in multivariate analyses.

CONCLUSIONS

Baseline US findings indicating MSU deposits and US-detected inflammation are independent predictors of gout flares over 12 months.

Acute gout attacks during the perioperative period and risk factors of recurrence after orthopedic surgery among untreated gout patients

BACKGROUND

This study aimed to explore the clinical characteristics of perioperative acute gout attacks in patients with varying uric acid levels undergoing orthopedic surgery, identify the risk factors for gout recurrence within the first postoperative year, and provide a disease prevention and diagnostic reference.

METHODS

This hospital-based retrospective study was conducted between January 2018 and December 2020. According to the blood uric acid levels at admission, the patients were grouped into either the normal uric acid level group or the hyperuricemia group. Patient comorbidities, serum uric acid levels, inflammatory indicators, follow-up recurrence rates, and other indicators were compared.

RESULT

The uric acid decline ratio and the inflammatory indexes (white blood cell count and C-reactive protein level) at the time of the attack were significantly higher in the normal uric acid level group than in the hyperuricemia group (P < 0.05). Patients in the hyperuricemia group with diabetes and tophi and those administered diuretics were more prone to acute gout attacks than those in the normal uric acid level group (P < 0.05). In the normal uric acid level group, 22 patients (84.6%) exhibited single joint involvement, whereas only 18 patients (47.4%) in the hyperuricemia group demonstrated single joint involvement (P < 0.05). After 1 year of follow-up, the gout recurrence rate in the hyperuricemia group was 44.7%, which was significantly higher that the recurrence rate in the normoglycemic group (11.5%; P < 0.05). Presenting tophi in perioperative orthopedic surgery patients was found to be an independent risk factor for gout recurrence within 1 year (RR = 4.80; P = 0.029).

CONCLUSION

The recurrence rate of gout in patients with hyperuricemia during perioperative period increased 1 year after operation. Therefore, it is crucial to monitor the uric acid level to prevent acute gout attacks during the perioperative period and recurrence during the 1-year follow-up period. Moreover, the risk of an acute gout recurrence 1 year after operation increased in patients who presented tophi; therefore, it is necessary to maintain appropriate blood uric acid level during perioperative period among patients undergoing orthopedic surgery.

Gout and Excess Risk of Severe SARS-CoV-2 Infection Among Vaccinated Individuals: A General Population Study

OBJECTIVE

Gout patients often have multiple comorbidities, making them susceptible to SARS-CoV-2 infection and poor outcomes. This study was undertaken to examine the association between gout and the risk of SARS-CoV-2 infection and severe outcomes, especially in patients who have received a SARS-CoV-2 vaccine.

METHODS

We conducted 2 cohort studies using The Health Improvement Network in the UK. Individuals with gout and those without gout from the general population were followed up from December 8, 2020 to October 31, 2021. We estimated the rate difference (RD) and hazard ratio (HR) of SARS-CoV-2 infection and severe outcomes (i.e., hospitalization and death within 30 days after SARS-CoV-2 infection) for individuals with gout versus those without gout using a Cox proportional hazards model according to SARS-CoV-2 vaccination status. We adjusted for potential confounders by using overlap weighting of exposure scores.

RESULTS

Among the vaccinated cohort, 1,955 cases of breakthrough COVID-19 infection occurred in 54,576 individuals with gout (4.68 cases per 1,000 person-months), and 52,468 cases occurred in 1,336,377 individuals without gout (3.76 cases per 1,000 person-months). The partially adjusted RD of breakthrough infection was 0.91 cases per 1,000 person-months (95% confidence interval [95% CI] 0.62-1.20 cases per 1,000 person-months), and the partially adjusted HR was 1.24 (95% CI 1.19-1.30). Gout was also associated with an increased risk of hospitalization (adjusted HR 1.30 [95% CI 1.10-1.53]) and death (adjusted HR 1.36 [95% CI 0.87-2.13]). Women with gout had an increased risk of hospitalization (adjusted HR 1.55 [95% CI 1.15-2.10]) and death (adjusted HR 2.46 [95% CI 1.12-5.41]). Similar associations with gout were observed in the unvaccinated cohort.

CONCLUSION

These general population data suggest that individuals with gout, especially women, have higher risks of SARS-CoV-2 infection and severe outcomes, even when vaccinated.

A retrospective observational study of the appropriate starting dose of febuxostat in patients with gout

BACKGROUND/AIMS

The occurrence of gout attacks at the start of uric acid lowering treatment worsens compliance. We aimed to determine the appropriate dose of febuxostat to reduce the occurrence of gout attacks during the initial treatment period.

METHODS

We retrospectively analyzed the data of patients diagnosed with gout who underwent treatment at Jeju National University Hospital between May 2018 and May 2020.

RESULTS

Two-hundred and twenty-seven patients were included, with a mean age of 53.2 ± 16.4 years, and 219 (96.5%) were male. The patients were divided into two groups according to the starting dose of febuxostat (20 mg vs. 40 mg). There were no significant differences in mean age, disease duration, colchicine, estimated glomerular filtration rate (eGFR), initial uric acid levels, and presence of subcutaneous tophi between the two groups. Gout attacks occurred more frequently in the 20 mg group than in the 40 mg group during the first 3 months of treatment (32.0% vs. 14.3%, p = 0.002), particularly during the first month (21.3% vs. 7.5%, p = 0.005). Multivariate logistic regression analysis was conducted adjusting for the effects of disease duration, the presence of subcutaneous tophi, eGFR, and initial uric acid levels. A febuxostat starting dose of 40 mg (odds ratio, 0.464; 95% confidence interval [CI], 0.246 to 0.862; p = 0.015) and anti-inflammatory prophylaxis (odds ratio, 0.359; 95% CI, 0.158 to 0.813; p = 0.014) were found to be independent factors associated with a gout attack.

CONCLUSIONS

Starting uric acid lowering treatment with febuxostat 40 mg rather than 20 mg may reduce the incidence of gout attacks in the early period of treatment in Korean patients with gout.

Risk of gout flares after COVID-19 vaccination: A case-crossover study

OBJECTIVE

Routine vaccinations are associated with an increased risk of gout flares. We examined the association between COVID-19 vaccination, an immunization program implemented to a large proportion of population, and the risk of gout flares.

METHODS

We conducted a time-stratified case-crossover study among patients with gout who experienced gout flares between December 2020 and September 2021, using data from The Health Improvement Network. We compared the risk of gout flares on each of the seven days on and after the day of COVID-19 vaccination vs. no vaccination during that period using conditional logistic regression. In addition, we performed subgroup analyses stratified by different COVID-19 vaccines (i.e., BNT162b2, hereafter referred to as BNT, and ChAdOx1 nCov-19, hereafter referred to as ChAd).

RESULTS

Among 5,904 patients with gout (mean age: 63·1 years; 85·5% male) who experienced gout flares within one month, the risk of gout flares slightly increased on the second day after COVID-19 vaccination (odds ratio: 1·44; 95% CI: 1·02 to 2·07). The risk of gout flares also slightly increased after receiving COVID-19 vaccine on other remaining days (ORs ranged from 1·03 to 1·22); however, none of them was statistically significant. An increased risk of gout flares on the second day after vaccination was mainly observed for the ChAd vaccine (odds ratio: 1·44; 95% CI: 1·00 to 2·05), but not for BNT vaccine (odds ratio: 1·18; 95% CI: 0·67 to 2·02).

CONCLUSION

COVID-19 vaccination, mainly ChAd vaccination, slightly increases the risk of gout flares on the second day after vaccination. This finding reassures the safety of COVID-19 vaccination for patients with gout.

Association Between Gout Flare and Subsequent Cardiovascular Events Among Patients With Gout

IMPORTANCE

Gout is associated with cardiovascular diseases. The temporal association between gout flares and cardiovascular events has not been investigated.

OBJECTIVE

To investigate whether there is a transient increase in risk of cardiovascular events after a recent gout flare.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective observational study was conducted using electronic health records from the Clinical Practice Research Datalink in England between January 1, 1997, and December 31, 2020. A multivariable nested case-control study was performed among 62 574 patients with gout, and a self-controlled case series, adjusted for season and age, was performed among 1421 patients with gout flare and cardiovascular event.

EXPOSURES

Gout flares were ascertained using hospitalization, primary care outpatient, and prescription records.

MAIN OUTCOMES AND MEASURES

The primary outcome was a cardiovascular event, defined as an acute myocardial infarction or stroke. Association with recent prior gout flares was measured using adjusted odds ratios (ORs) with 95% CIs in a nested case-control study and adjusted incidence rate ratios (IRRs) with 95% CIs in a self-controlled case series.

RESULTS

Among patients with a new diagnosis of gout (mean age, 76.5 years; 69.3% men, 30.7% women), 10 475 patients with subsequent cardiovascular events were matched with 52 099 patients without cardiovascular events. Patients with cardiovascular events, compared with those who did not have cardiovascular events, had significantly higher odds of gout flare within the prior 0 to 60 days (204/10 475 [2.0%] vs 743/52 099 [1.4%]; adjusted OR, 1.93 [95% CI, 1.57-2.38]) and within the prior 61 to 120 days (170/10 475 [1.6%] vs 628/52 099 [1.2%]; adjusted OR, 1.57 [95% CI, 1.26-1.96]). There was no significant difference in the odds of gout flare within the prior 121 to 180 days (148/10 475 [1.4%] vs 662/52 099 [1.3%]; adjusted OR, 1.06 [95% CI, 0.84-1.34]). In the self-controlled case series (N = 1421), cardiovascular event rates per 1000 person-days were 2.49 (95% CI, 2.16-2.82) within days 0 to 60; 2.16 (95% CI, 1.85-2.47) within days 61 to 120; and 1.70 (95% CI, 1.42-1.98) within days 121 to 180 after a gout flare, compared with cardiovascular event rates of 1.32 (95% CI, 1.23-1.41) per 1000 person-days within the 150 days before or the 181 to 540 days after the gout flare. Compared with 150 days before or the 181 to 540 days after a gout flare, incidence rate differences for cardiovascular events were 1.17 (95% CI, 0.83-1.52) per 1000 person-days, and adjusted IRRs were 1.89 (95% CI, 1.54-2.30) within days 0 to 60; 0.84 (95% CI, 0.52-1.17) per 1000 person-days and 1.64 (95% CI, 1.45-1.86) within days 61 to 120; and 0.38 (95% CI, 0.09-0.67) per 1000 person-days and 1.29 (95% CI, 1.02-1.64) within days 121 to 180 after a gout flare.

CONCLUSIONS AND RELEVANCE

Among individuals with gout, those who experienced a cardiovascular event, compared with those who did not experience such an event, had significantly higher odds of a recent gout flare in the preceding days. These findings suggest gout flares are associated with a transient increase in cardiovascular events following the flare.

A Pain in the Foot: Delayed Diagnosis of Primary Septic Arthritis of Naviculocuneiform and Second/Third Tarsometatarsal Joints

Patient: Male, 65-year-old

Final Diagnosis: Septic arthritis of midfoot

Symptoms: Foot pain

Medication: —

Clinical Procedure: Debridement • drainage

Specialty: Family Medicine • General and Internal Medicine • Orthopedics • Emergency Medicine

Dietary and Lifestyle-Centered Approach in Gout Care and Prevention

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Unravelling the mysteries of gout by multimodality imaging

Gout is a common inflammatory arthritis that manifests as an aggregate of variably symptomatic monosodium urate crystals (MSU) in the joints and surrounding tissues in addition to multisystem involvement such as genitourinary and cardiovascular systems. In recent decades, there has been a documented increase in the prevalence and incidence of gout. Risk factors for gout include obesity, dietary influences, hypertension, renal impairment, and diuretic use. A prompt diagnosis followed by uric acid lowering treatment prior to the onset of bone destruction is the goal in any suspected case of gout. Advanced imaging modalities, such as dual energy computed tomography (DECT) and ultrasonography (US), employed for the diagnosis of gout are each accompanied by advantages and disadvantages. Conventional radiography (CR), although useful in visualizing joint erosions and mineralization, is limited in its ability to diagnose gout flare. Although synovial fluid aspiration remains the gold standard for MSU crystal visualization, less-invasive imaging modalities are preferred to avoid potential complications. DECT and US in particular are useful in the diagnosis of gout. In this review, we will discuss the current state and role of imaging in the detection of gout.

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

Objectives

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

Methods

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

Results

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

Conclusions

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

Trial registration number

UMIN000039985.

Outcomes of Care Among Patients With Gout in Europe: A Cross-sectional Survey

OBJECTIVE

To assess health- and patient-centered outcomes in gout across Europe, and explore patient-, care-, and country-level characteristics associated with these outcomes.

METHODS

Patients with self-reported physician-diagnosed gout from 14 European countries completed an online survey. Multivariable mixed-effect logistic and linear regressions were computed for health outcomes (gout flare recurrence) and patient-centered outcomes (patient satisfaction with current medication, and unaddressed goals), accounting for clustering within countries. The role of patient-, care-, and country-level factors was explored.

RESULTS

Participants included 1029 patients, predominantly diagnosed by a general practitioner (GP). One or more gout flares were reported by 70% of patients and ≥ 3 flares by 32%. Gout patients reported 1.1 ± 1.2 unaddressed goals, and 80% were satisfied with current medication. Patients with ≥ 3 and ≥ 1 flares were less likely to be treated with urate-lowering therapy (ULT) (OR 0.52, 95% CI 0.39-0.70 and OR 0.38, 95% CI 0.28-0.53, respectively), but more likely to have regular physician visits (OR 2.40, 95% CI 1.79-3.22 and OR 1.77, 95% CI 1.30-2.41). Three or more gout flares were also associated with lower satisfaction (OR 0.39, 95% CI 0.28-0.56) and more unaddressed goals (β 0.36, 95% CI 0.19-0.53). Notwithstanding, the predicted probability of being satisfied was still between 57% and 75% among patients with ≥ 3 flares but who were not receiving ULT. Finally, patients from wealthier and Northern European countries more frequently had ≥ 3 gout flares.

CONCLUSION

Across Europe, many patients with gout remain untreated despite frequent reported flares. Remarkably, a substantial proportion of them were still satisfied with gout management. A better understanding of patients' satisfaction and its role in physicians' gout management decisions is warranted to improve quality of care and gout outcomes across Europe.

Gout

Gout is a common and treatable disease caused by the deposition of monosodium urate crystals in articular and non-articular structures. Increased concentration of serum urate (hyperuricaemia) is the most important risk factor for the development of gout. Serum urate is regulated by urate transporters in the kidney and gut, particularly GLUT9 (SLC2A9), URAT1 (SLC22A12), and ABCG2. Activation of the NLRP3 inflammasome by monosodium urate crystals with release of IL-1β plays a major role in the initiation of the gout flare; aggregated neutrophil extracellular traps are important in the resolution phase. Although presenting as an intermittent flaring condition, gout is a chronic disease. Long-term urate lowering therapy (eg, allopurinol) leads to the dissolution of monosodium urate crystals, ultimately resulting in the prevention of gout flares and tophi and in improved quality of life. Strategies such as nurse-led care are effective in delivering high-quality gout care and lead to major improvements in patient outcomes.

Reducing Immunogenicity of Pegloticase With Concomitant Use of Mycophenolate Mofetil in Patients With Refractory Gout: A Phase II, Randomized, Double-Blind, Placebo-Controlled Trial

OBJECTIVE

Pegloticase is used for the treatment of severe gout, but its use is limited by immunogenicity. This study was undertaken to evaluate whether mycophenolate mofetil (MMF) prolongs the efficacy of pegloticase.

METHODS

Participants were randomized 3:1 to receive 1,000 mg MMF twice daily or placebo for 14 weeks, starting 2 weeks before receiving pegloticase and continuing while receiving intravenous pegloticase 8 mg biweekly for 12 weeks. Participants then received pegloticase alone from week 12 to week 24. The primary end points were the proportion of patients who sustained a serum urate level of ≤6 mg/dl at 12 weeks and the rate of adverse events (AEs). Secondary end points included 24-week durability of serum urate level ≤6 mg/dl. Fisher's exact test and Wilcoxon's 2-sample test were used for analyses, along with Kaplan-Meier estimates and log rank tests.

RESULTS

A total of 32 participants received ≥1 dose of pegloticase. Participants were predominantly men (88%), with a mean age of 55.2 years, mean gout duration of 13.4 years, and mean baseline serum urate level of 9.2 mg/dl. At 12 weeks, a serum urate level of ≤6 mg/dl was achieved in 19 (86%) of 22 participants in the MMF arm compared to 4 (40%) of 10 in the placebo arm (P = 0.01). At week 24, the serum urate level was ≤6 mg/dl in 68% of MMF-treated patients versus 30% of placebo-treated patients (P = 0.06), and rates of AEs were similar between groups, with more infusion reactions occurring in the placebo arm (30% versus 0%).

CONCLUSION

Our findings indicate that MMF therapy with pegloticase is well tolerated and shows a clinically meaningful improvement in targeted serum urate level of ≤6 mg/dl at 12 and 24 weeks. This study suggests an innovative approach to pegloticase therapy in gout.

Onset of comorbidities and flare patterns within pre-existing morbidity clusters in people with gout: 5-year primary care cohort study

Objective

To investigate the onset of comorbidities and pattern of flares over 5 years according to baseline comorbidity clusters in people with gout.

Methods

In a prospective primary care-based cohort study, adults aged ≥18 years with gout were identified from primary care medical records in 20 general practices across the West Midlands, UK and followed up over 5 years. Four clusters of participants have been defined previously according to baseline comorbidity status. The associations of (i) incident comorbidities and (ii) gout flares with baseline cluster membership were estimated using age and sex-adjusted Poisson regression and mixed effects ordinal logistic regression, respectively.

Results

The comorbidity with the highest incidence was coronary artery disease (39.2%), followed by hypertension (36.7%), chronic kidney disease stage ≥3 (18.1%), obesity (16.0%), hyperlipidaemia (11.7%), diabetes (8.8%) and cancer (8.4%). There were statistically significant associations observed between cluster membership and incidence of coronary artery disease, hyperlipidaemia, heart failure and hypertension. In each cluster, nearly one-third of participants reported two or more gout flares at each time-point. History of oligo/polyarticular flares (odds ratio [OR]= 2.16, 95% confidence interval [CI]: 1.73, 2.70) and obesity (1.66, 95% CI: 1.21, 2.25) were associated with increasing flares whereas current use of allopurinol was associated with lower risk (0.42, 95% CI: 0.34–0.53). Cluster membership was not associated with flares.

Conclusion

Substantial numbers of people in each cluster developed new comorbidities that varies by cluster membership. People also experienced multiple flares over time, but these did not differ between clusters. Clinicians should be vigilant for the development of new comorbidities in people with gout.

Comorbidities and factors influencing frequent gout attacks in patients with gout: a cross-sectional study

OBJECTIVES

The objective was to identify the comorbidities of gout, to compare gender difference and independent factors of frequent gout attacks (> 20 times).

METHOD

Demographic, clinical variables, self-reported comorbidities, and biochemical variables (i.e., initial serum uric acid (UA) and UA at visit) were collected in this cross-sectional study. Gout attack times were recorded as ≤ 5, 6-10, 11-20, and > 20. Adjusted odds ratio (OR) and corresponding 95% confidence interval (CI) were calculated to explore the association between selected risk factors and frequent gout attacks.

RESULTS

Six hundred fifty-three gout patients with a mean age of 48.3 ± 15.8 years were included, 84.7% of whom were males. The median gout duration was 6.0 (3.0-12.0) years. The most common comorbidities involved hypertension (166, 25.4%), coronary artery disease (CAD) (67, 10.3%), chronic kidney disease (66, 10.1%), and hyperlipidemia (57, 8.7%). Abnormalities including nephrolithiasis (29.4%), hydronephrosis (3.2%), and gallstones (11.9%) were also found. Although female patients had a longer disease duration and more CAD, they had a lower level of UA, creatine, and C-reactive protein (CRP) but higher high-density lipoprotein cholesterol (HDL-C) (p < 0.05). A positive correlation between UA and triglycerides was found in females (p = 0.039). Patients with renal insufficiency or nephrolithiasis had longer disease duration and more gout attacks (p < 0.001). In multivariable regression analysis, only gout duration (OR = 7.89, p < 0.001) and UA (OR = 1.48, p < 0.001) was independent factors of frequent gout attacks.

CONCLUSIONS

Comorbidity screening involving dyslipidemia is often neglected in gout patients. Gout duration and UA are the risk factors of frequent gout attacks. Key Points • Comorbidities can be overlooked if the screening for lipid levels, cardiovascular disease, and kidney disease is not completed. • There are differences in comorbidities and biochemical findings between male and female patients with gout. • Gout duration and serum uric acid level are independent risk factors of frequent gout attacks.

Association of urate deposition shown by ultrasound and frequent gout attacks

BACKGROUND

There are few data demonstrating the association between urate burden assessed by ultrasound (US) and gout flares. The aim of this study was to determine the association of urate deposition shown by US and frequent gout attacks.

MATERIALS AND METHODS

Patients with gout were divided into two groups according to the frequency of gout attacks in the previous 12 months: frequent (>2 attacks) and infrequent (0-2 attacks). Urate deposition in the hands, knees, and feet was assessed by US.

RESULTS

Overall, 106 patients were enrolled in this study, of whom 32 (30.1%) had had frequent gout attacks (>2 attacks) in the previous 12 months (the average number of gout attacks was 4.7, range 3-12). Those with frequent gout attacks had significantly longer gout duration, a higher serum urate level, and more urate deposition shown by US than those with infrequent gout attacks (P < 0.05). In both univariate and logistic regression analyses, frequent gout attacks were correlated with gout duration, serum urate level, and urate deposition as shown by US (P < 0.05).

CONCLUSION

These findings indicate that urate deposition shown by US is independently associated with frequent gout attacks. Special attention should be given to the prevention of flares in patients with an initially high urate burden as assessed by US.

Real-world treatment of gout and asymptomatic hyperuricemia: A cross-sectional study of Japanese health insurance claims data

OBJECTIVES

To assess gout and asymptomatic hyperuricemia in Japan and review treatment conditions.

METHODS

This retrospective cross-sectional study analyzed the prevalence of hyperuricemia and gout, and characteristics and treatment of patients with those conditions, using Japanese health insurance claims and medical check-up data collected from April 2016 through March 2017.

RESULTS

Among 2,531,383 persons registered in the database, 1.1% (men 1.9%, women <0.1%) were diagnosed with gout and 2.6% (4.1%, 0.4%) with asymptomatic hyperuricemia. Medical check-ups showed 13.4% (19.6%, 1.0%) of patients with hyperuricemia (serum uric acid [sUA] > 7.0 mg/dL). Urate-lowering therapy (ULT) was prescribed for 80.7% of patients identified with gout and 72.4% identified with asymptomatic hyperuricemia. ULT adherence was satisfactory, but most patients were treated with low-dose ULT. Less than half of patients receiving ULT achieved the sUA target (≤6.0 mg/dL). In gout patients, the incidence of gout flare was 47.8% (0.74 flares/person-year).

CONCLUSIONS

Although hyperuricemia prevalence is similar in Japan and worldwide, gout is comparatively rare in Japan. Gout and asymptomatic hyperuricemia are often treated with low-dose ULT, and many patients fail to reach target sUA, suggesting that gout management is suboptimal in Japan. Patients would benefit from stricter focus on a treat-to-target approach for gout management.

Gout After Total Knee Arthroplasty

Crystalline arthropathies are well-known pathologies in a native knee; however, the literature is scarce with regards to crystalline arthropathies in a total knee arthroplasty (TKA). The presentation of crystalline arthropathy in a TKA can be similar to a periprosthetic joint infection (PJI), making it difficult to distinguish between the 2 diagnoses. We present 1 case highlighting the similarity between crystalline arthropathy and PJI. A 71-year-old man with a history of bilateral TKAs presented with bilateral painful knee effusions and was initially presumed to have PJIs; however, he was later diagnosed with gout and successfully treated medically. A complete review of the literature demonstrates that crystalline arthropathies after TKA are infrequently reported and can be difficult to decipher from PJIs, and there is a lack of standardized treatment.

Quality of gout care in the emergency departments: a multicentre study

BACKGROUND

To report on prevalence of gout flare in emergency departments and to report the quality of gout care in emergency departments and causes of admission at emergency departments.

METHODS

A retrospective chart review of visits that had a primary diagnosis in gout by the International Classification of Diseases, the tenth revision, at emergency departments from 6 universities in Thailand over a 5 year period from 1 January 2012 to 31 December 2016.

RESULTS

Six hundred thirty-two visits were included to the study. Prevalence of gout flare in emergency departments was 0.04. Only 29.3% of the visits had arthrocentesis. 628/632 (99.4%) and 519/585 (88.7%) of the visits were prescribed medications in emergency departments and had home medications, respectively. Although all visits that were prescribed colchicine in emergency departments received adequate doses of colchicine, it was also found that more than 2.4 mg/day of colchicine was prescribed (3/394, 0.8%) for home medications. In addition, 183/343 (53.4%) of the visits with normal renal function were prescribed non-steroidal anti-inflammatory drugs (NSAIDs). However, prescribed NSAIDs in abnormal renal function (42/343, 12.2%) was also found. The interruption of dosing, including increase, decrease, addition or discontinuance of urate lowing therapy in a gout flare period was 42/632 (6.6%). The most common cause of admission was acute gouty arthritis (31/47, 66.0%).

CONCLUSIONS

Quality of gout care in the emergency departments was not good. Inappropriate management of gout flare in emergency departments was demonstrated in our study, particularly with regard to investigations and pharmacological management. Gaps between clinicians and guidelines, the knowledge of clinicians, and overcrowding in emergency departments were hypothesized in the results.

Effect of tart cherry juice on risk of gout attacks: protocol for a randomised controlled trial

INTRODUCTION

Gout is a painful form of inflammatory arthritis associated with several comorbidities, particularly cardiovascular disease. Cherries, which are rich in anti-inflammatory and antioxidative bioactive compounds, are proposed to be efficacious in preventing and treating gout, but recommendations to patients are conflicting. Cherry consumption has been demonstrated to lower serum urate levels and inflammation in several small studies. One observational case cross-over study reported that cherry consumption was associated with reduced risk of recurrent gout attacks. This preliminary evidence requires substantiation. The proposed randomised clinical trial aims to test the effect of consumption of tart cherry juice on risk of gout attacks.

METHODS AND ANALYSIS

This 12-month, parallel, double-blind, randomised, placebo-controlled trial will recruit 120 individuals (aged 18-80 years) with a clinical diagnosis of gout who have self-reported a gout flare in the previous year. Participants will be randomly assigned to an intervention group, which will receive Montmorency tart cherry juice daily for a 12-month period, or a corresponding placebo group, which will receive a cherry-flavoured placebo drink. The primary study outcome is change in frequency of self-reported gout attacks. Secondary outcome measures include attack intensity, serum urate concentration, fractional excretion of uric acid, biomarkers of inflammation, blood lipids and other markers of cardiovascular risk. Other secondary outcome measures will be changes in physical activity and functional status. Statistical analysis will be conducted on an intention-to-treat basis.

ETHICS AND DISSEMINATION

This study has been granted ethical approval by the National Research Ethics Service, Yorkshire and The Humber-Leeds West Research Ethics Committee (ref: 18/SW/0262). Results of the trial will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT03621215.

Clinical features and recurrent attack in gout patients according to serum urate levels during an acute attack

BACKGROUND/AIMS

A substantial portion of gout patients have normal serum urate levels during an acute attack but data on the clinical characteristics and risk of recurrence compared with hyperuricemic patients are limited.

METHODS

In this retrospective cohort study, clinical features of normouricemic and hyperuricemic patients were compared. Multivariate analysis was performed to determine whether normouricemic patients were less likely to have a recurrent attack.

RESULTS

Among a total of 221 gout patients, 88 (39.8%) had normouricemia during an acute attack. Postsurgical gout (22.7% vs. 6.0%, p < 0.001), hemodialysis initiation (9.1% vs. 2.3%, p = 0.029) and inflammatory activity were higher in normouricemic patients than in hyperuricemic patients. The frequency of renal insufficiency was lower in normouricemic patients (25.0% vs. 53.4%, p < 0.001). However, the recurrence rate of gout attack was not different between the two groups (24.7% vs. 33.0%, p = 0.220). In multivariate analysis, female sex, history of urinary stone, presence of tophi, and use of thiazide were associated with increase of recurrent gout attack, but not with serum urate status during an acute attack (hazard ratio, 1.075; 95% confidence interval, 0.972 to 1.190; p = 0.159).

CONCLUSION

Normouricemia during an acute gout attack was more frequently observed in postsurgical episodes, hemodialysis initiation and patients with preserved renal function. While higher inflammatory activity was observed in normouricemic patients, recurrent attack was not associated with serum urate levels during an acute attack. Thus, careful follow-up should be considered in gout patients regardless of serum urate levels during an acute attack.

[Hyperuricemia, gout and high cardiovascular risk - how to manage them in clinical practice]

In recent years, the relationship of hyperuricemia and gout with a high risk of cardiovascular disease has been widely discussed. Therefore, it is important to systematically examine patients in order to diagnose comorbidities, among which cardiovascular disease and its complications occupy a leading place and consider mandatory treatment of patients with hyperuricemia and gout with high cardiovascular risk with lowering drugs, which fully reflects the provisions of the latest European recommendations for the management and treatment of patients with gout.

Interaction of the p.Q141K Variant of the ABCG2 Gene with Clinical Data and Cytokine Levels in Primary Hyperuricemia and Gout

Gout is an inflammatory arthritis influenced by environmental risk factors and genetic variants. The common dysfunctional p.Q141K allele of the ABCG2 gene affects gout development. We sought after the possible association between the p.Q141K variant and gout risk factors, biochemical, and clinical determinants in hyperuricemic, gouty, and acute gouty arthritis cohorts. Further, we studied the correlation of p.Q141K allele and levels of pro-/anti-inflammatory cytokines. Coding regions of the ABCG2 gene were analyzed in 70 primary hyperuricemic, 182 gout patients, and 132 normouricemic individuals. Their genotypes were compared with demographic and clinical parameters. Plasma levels of 27 cytokines were determined using a human multiplex cytokine assay. The p.Q141K variant was observed in younger hyperuricemic/gout individuals (p = 0.0003), which was associated with earlier disease onset (p = 0.004), trend toward lower BMI (p = 0.056), and C-reactive protein (CRP, p = 0.007) but a higher glomerular filtration rate (GFR, p = 0.035). Levels of 19 cytokines were higher, mainly in patients with acute gouty arthritis (p < 0.001), irrespective of the presence of the p.Q141K variant. The p.Q141K variant influences the age of onset of primary hyperuricemia or gout and other disease-linked risk factors and symptoms. There was no association with cytokine levels in the circulation.

Acute Calcium Pyrophosphate Crystal Arthritis Flare Rate and Risk Factors for Recurrence

OBJECTIVE

Little is known about acute calcium pyrophosphate (CPP) crystal arthritis flare rates and risk factors for recurrence. We characterized flares and determined the rate and predictors of acute CPP crystal arthritis flares in an academic medical center cohort.

METHODS

We performed a retrospective cohort study among a random sample of patients with acute CPP crystal arthritis identified in the Partners HealthCare electronic medical record, 1991-2017. Flare was defined as self-limited, acute-onset synovitis with synovial fluid CPP crystals and/or chondrocalcinosis, not better explained by another cause. We calculated incidence rates (IR) for acute CPP crystal arthritis flare among all subjects and by sex. We estimated HR for recurrent flare using univariate Cox models that accounted for within-person correlated data.

RESULTS

We identified 70 patients with acute CPP crystal arthritis with a total of 111 flares. Recurrent flares occurred in 24% of patients; half of flares occurred in a previously unaffected joint. The acute CPP crystal arthritis flare rate was 11.4 per 100 person-years overall (95% CI 8.2-15.4), 14.2 in women (95% CI 9.6-0.1), and 7.1 in men (95% CI 3.4-13.0). Cancer (HR 2.98, 95% CI 1.33-6.68) and chronic kidney disease (HR 2.92, 95% CI 1.10-7.76) were associated with a higher rate for recurrent flare.

CONCLUSION

Recurrent flares occurred in about one-fourth of patients with acute CPP crystal arthritis and often occurred in previously unaffected joints. The acute CPP crystal arthritis flare rate was twice as high in women as in men.

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.

Gout

Gout is a chronic disease caused by monosodium urate (MSU) crystal deposition. Gout typically presents as an acute, self-limiting inflammatory monoarthritis that affects the joints of the lower limb. Elevated serum urate level (hyperuricaemia) is the major risk factor for MSU crystal deposition and development of gout. Although traditionally considered a disorder of purine metabolism, altered urate transport, both in the gut and the kidneys, has a key role in the pathogenesis of hyperuricaemia. Anti-inflammatory agents, such corticosteroids, NSAIDs and colchicine, are widely used for the treatment of gout flare; recognition of the importance of NLRP3 inflammasome activation and bioactive IL-1β release in initiation of the gout flare has led to the development of anti-IL-1β biological therapy for gout flares. Sustained reduction in serum urate levels using urate-lowering therapy is vital in the long-term management of gout, which aims to dissolve MSU crystals, suppress gout flares and resolve tophi. Allopurinol is the first-line urate-lowering therapy and should be started at a low dose, with gradual dose escalation. Low-dose anti-inflammatory therapies can reduce gout flares during initiation of urate-lowering therapy. Models of care, such as nurse-led strategies that focus on patient engagement and education, substantially improve clinical outcomes and now represent best practice for gout management.

Changes in the Presentation of Incident Gout and the Risk of Subsequent Flares: A Population-based Study over 20 Years

OBJECTIVE

To examine whether a change in the presentation of incident gout happened over the last 20 years and to determine the risk of subsequent gout flares after an initial gout attack.

METHODS

All incident cases of gout were identified among residents of Olmsted County, Minnesota, diagnosed in 1989-1992 and 2009-2010 according to the earliest date fulfilling the 1977 American Rheumatism Association preliminary criteria, or the New York or Rome criteria for gout. Patients in both cohorts were then followed for up to 5 years. Cumulative incidence and person-year methods were used to compare flare rates, and conditional frailty models were used to examine predictors.

RESULTS

A total of 429 patients with incident gout (158 patients in 1989-1992 and 271 patients in 2009-2010) were identified and followed for a mean of 4.2 years. The majority of patients were male (73%) and the mean age (SD) at gout onset was 59.7 (17.3) years. Classic podagra decreased significantly from 74% to 59% (p < 0.001). Cumulative incidence of first flare was similar in both cohorts (62% vs 60% by 5 yrs in 1989-1992 and 2009-2010, respectively; p = 0.70), but overall flare rate was marginally higher in 2009-2010 compared to 1989-1992 (rate ratio: 1.24). Hyperuricemia (HR 1.59) and kidney disease (HR 1.34) were significant predictors of future flares.

CONCLUSION

Gout flares were common in both time periods. Hyperuricemia and kidney disease were predictors of future flares in patients with gout. Podagra as a presentation of gout has become relatively less frequent in recent years.

Prescribing patterns and healthcare costs of gout

OBJECTIVE/METHODS

The Longitudinal Health Insurance Database (LHID) 2010 was used to identify gout cases and their number of gout flares.

RESULTS

Out of 21,376 gout patients, a total of 3561 (16.7%) had frequent gout flares (≥3 gout flares/year). Average all-cause healthcare utilization (35.9 visits vs. 30.7 visits; p < .001) and gout-related utilization (22.7 visits vs. 15.6 visits; p < .001) were higher in frequent gout flare patients than in those with infrequent gout flares. The median gout-related cost (USD $369 vs. $285; p < .001), but not all-cause costs (p = .25), were higher in frequent gout flare patients compared to the infrequent group. Over 55.8% of the flares were treated with colchicine + NSAIDs.

CONCLUSIONS

In conclusion, patients with frequent gout flares had higher healthcare utilization and gout-related healthcare costs. Colchicine + NSAIDs are commonly used therapy for gout flare.

Gout, flares, and allopurinol use: a population-based study

BACKGROUND

There is a paucity of community-based data regarding the prevalence and impact of gout flares as these may often be self-managed. The aim of this study was to determine the prevalence of self-reported gout and gout flares, the use of urate-lowering therapy (ULT), and the association of gout flares with health-related quality of life (HRQoL) in a large community sample. Covariate associations with flare frequency and allopurinol use were also examined.

METHODS

The South Australian Health Omnibus Survey is an annual, face-to-face population-based survey. Data collected in the 2017 survey included self-reported medically diagnosed gout, allopurinol use (first-line ULT in Australia), and gout attacks (flares) in the last 12 months, in addition to sociodemographic variables and health-related quality of life (HRQoL, SF-12). Data were weighted to the Australian Bureau of Statistics 2016 census data to reflect the South Australian population. Participants 25 years and over (n = 2778) were included in the analysis.

RESULTS

The prevalence of gout was 6.5% (95%CI 5.5, 7.5). Amongst participants with gout, 37.1% (95%CI 29.6, 45.3) reported currently using allopurinol, while 23.2% (95%CI 16.9, 21.0) reported prior use (38% discontinuation rate). Frequent flares (≥ 2 in the last year) were reported by 25% of participants with gout and were more likely with younger age, higher body mass index, and current allopurinol use (p < 0.05). The frequency of gout flares was associated with a lower physical HRQoL (p = 0.012). Current allopurinol use was reported by 51% of participants with frequent gout flares.

CONCLUSION

Flares were frequently reported by people with gout in the community. Gout flares were associated with reduced physical HRQoL. Almost one half of people with frequent gout flares were not receiving allopurinol, and current allopurinol use was associated with frequent gout flares, suggesting undertreated disease and suboptimal use of ULT. Determining covariate associations with flares and ineffective allopurinol use may identify means of improving treatment and reducing flares.

Incident gout and chronic Kidney Disease: healthcare utilization and survival

Background

Uncontrolled gout can cause significant joint and organ damage and has been associated with impairments in quality of life and high economic cost. Gout has also been associated with other comorbid diseases, such as chronic kidney disease. The current study explored if healthcare resource utilization (HRU) and survival differs between patients with incident gout in the presence or absence of chronic kidney disease (CKD).

Methods

Clalit Health Services (CHS) data were used to conduct a retrospective population-based cohort study of incident gout between 1/1/2006–31/12/2009. Incident cases of gout were identified and stratified by CKD status and by age group (< 55 and 55+ years). CKD status was defined as a pre-existing diagnosis of chronic kidney disease, chronic renal failure, kidney transplantation, or dialysis at index date. Demographic and clinical characteristics, as well as healthcare resource use, were reported.

Results

A total of 12,940 incident adult gout patients, with (n = 8286) and without (n = 4654) CKD, were followed for 55,206 person-years. Higher rates of HRU were observed for gout patients with CKD than without. Total annual hospital admissions for patients with gout and CKD were at least 3 times higher for adults < 55 (mean = 0.51 vs 0.13) and approximately 1.5 times higher for adults 55+ (mean = 0.46 vs 0.29) without CKD. Healthcare utilization rates from year 1 to year 5 remained similar for gout patients < 55 years irrespective of CKD status, however varied according to healthcare utilization by CKD status for gout patients 55+ years. The 5-year all-cause mortality was higher among those with CKD compared to those without CKD for both age groups (HR_{< 55 years} = 1.65; 95% CI 1.01–2.71; HR_{55+ years} = 1.50; 95% CI 1.37–1.65).

Conclusions

The current study suggests important differences exist in patient characteristics and outcomes among patients with gout and CKD. Healthcare utilization differed between sub-populations, age and comorbidities, over the study period and the 5-year mortality risk was higher for gout patients with CKD, regardless of age. Future work should explore factors associated with these outcomes and barriers to gout control in order to enhance patient management among this high-risk subgroup.

Gout Activity Score has predictive validity and is sensitive to change: results from the Nottingham Gout Treatment Trial (Phase II)

OBJECTIVES

To examine the predictive validity of the Gout Activity Score (GAS), its correlation with the Gout Impact Scale (GIS) and their sensitivity to change.

METHODS

Data from a clinical trial in which participants with one or more gout flares in the previous year were recruited from primary care and randomized to nurse-led or continuing usual care were used in this study. GAS and GIS were calculated as described, with higher scores indicating worse disease activity and quality of life, respectively. The correlation between GAS and GIS was examined using Spearman's correlation. Standardized response means (SRMs) were calculated to assess sensitivity to change. The association between GAS at baseline and the number of flares in the next 12 months was evaluated using Poisson regression. Data analyses were performed using STATA version 14, with P-values <0.05 being statistically significant.

RESULTS

There was low positive correlation between GAS and gout concern overall and unmet treatment need subscales of GIS (r = 0.34-0.45). Female sex associated independently with fewer gout flares, while increasing GAS, BMI and age associated independently with frequent flares. Of all the outcome measures examined, GAS was the most responsive to change (SRM 0.89 to -0.53). Of the GIS domains, the gout concern overall domain had the best sensitivity to change (SRM 1.06-0.01).

CONCLUSION

GAS is sensitive to change, has predictive validity and correlates with relevant domains of GIS such as gout concern overall. Additional independent validation of GAS is required before it can be adopted in clinical practice.

Monosodium urate burden assessed with dual-energy computed tomography predicts the risk of flares in gout: a 12-month observational study : MSU burden and risk of gout flare

Background

Predicting the risk of flares in patients with gout is a challenge and the link between urate burden and the risk of gout flare is unclear. The objective of this study was to determine if the extent of monosodium urate (MSU) burden measured with dual-energy computed tomography (DECT) and ultrasonography (US) is predictive of the risk of gout flares.

Methods

This prospective observational study recruited patients with gout to undergo MSU burden assessment with DECT (volume of deposits) and US (double contour sign) scans of the knees and feet. Patients attended follow-up visits at 3, 6 and 12 months. Patients having presented with at least one flare at 6 months were compared to those who did not flare. Odds ratios (ORs) (95% confidence interval) for the risk of flare were calculated.

Results

Overall, 64/78 patients included attended at least one follow-up visit. In bivariate analysis, the number of joints with the double contour sign was not associated with the risk of flare (p = 0.67). Multivariate analysis retained a unique variable: DECT MSU volume of the feet. For each 1 cm³ increase in DECT MSU volume in foot deposits, the risk of flare increased 2.03-fold during the first 6 months after initial assessment (OR 2.03 (1.15–4.38)). The threshold volume best discriminating patients with and without flare was 0.81 cm³ (specificity 61%, sensitivity 77%).

Conclusions

This is the first study showing that the extent of MSU burden measured with DECT but not US is predictive of the risk of flares.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1714-9) contains supplementary material, which is available to authorized users.

Managing Gout Flares in the Elderly: Practical Considerations

Gout is common in the elderly, affecting an estimated 4.7 million people aged > 60 years in the USA alone. The incidence and prevalence of gout increases, and male predisposition to gout reduces, with increasing age. The elderly have more comorbidities, and gout manifests differently, with more frequent involvement of knees, ankles, and wrists at disease onset, systemic upset, and tophi. Comorbidities and polypharmacy make the management of gout flares challenging in this population. Intra-articular corticosteroid injection remains the treatment of choice for accessible joints, oral prednisolone is preferred over low-dose colchicine, and non-steroidal anti-inflammatory drugs (NSAIDs) are best avoided. Xanthine oxidase inhibitors (XOI) remain the first-line treatment for hyperuricemia in the elderly. Arhalofenate, an emerging uricosuric anti-inflammatory drug, prevents gout flares while reducing serum urate. It may be particularly relevant in the treatment of gout in the elderly as they are unable to tolerate long-term colchicine for flare prophylaxis and frequently have contraindications to corticosteroids and NSAIDs. However, given its modest urate-lowering effect, it can only be used in combination with an XOI, and the safety and efficacy of this drug has not been examined in the elderly or in those with chronic kidney disease. Diuretics and beta-blockers should be discontinued where feasible, whereas low-dose aspirin can be continued if otherwise indicated.

Functional non-synonymous variants of ABCG2 and gout risk

Objectives

Common dysfunctional variants of ATP binding cassette subfamily G member 2 (Junior blood group) (ABCG2), a high-capacity urate transporter gene, that result in decreased urate excretion are major causes of hyperuricemia and gout. In the present study, our objective was to determine the frequency and effect on gout of common and rare non-synonymous and other functional allelic variants in the ABCG2 gene.

Methods

The main cohort recruited from the Czech Republic consisted of 145 gout patients; 115 normouricaemic controls were used for comparison. We amplified, directly sequenced and analysed 15 ABCG2 exons. The associations between genetic variants and clinical phenotype were analysed using the t-test, Fisher's exact test and a logistic and linear regression approach. Data from a New Zealand Polynesian sample set and the UK Biobank were included for the p.V12M analysis.

Results

In the ABCG2 gene, 18 intronic (one dysfunctional splicing) and 11 exonic variants were detected: 9 were non-synonymous (2 common, 7 rare including 1 novel), namely p.V12M, p.Q141K, p.R147W, p.T153M, p.F373C, p.T434M, p.S476P, p.D620N and p.K360del. The p.Q141K (rs2231142) variant had a significantly higher minor allele frequency (0.23) in the gout patients compared with the European-origin population (0.09) and was significantly more common among gout patients than among normouricaemic controls (odds ratio = 3.26, P < 0.0001). Patients with non-synonymous allelic variants had an earlier onset of gout (42 vs 48 years, P = 0.0143) and a greater likelihood of a familial history of gout (41% vs 27%, odds ratio = 1.96, P = 0.053). In a meta-analysis p.V12M exerted a protective effect from gout (P < 0.0001).

Conclusion

Genetic variants of ABCG2, common and rare, increased the risk of gout. Non-synonymous allelic variants of ABCG2 had a significant effect on earlier onset of gout and the presence of a familial gout history. ABCG2 should thus be considered a common and significant risk factor for gout.