Epidemiology of gout: an update

The global burden of gout: estimates from the Global Burden of Disease 2010 study

OBJECTIVE

Gout is the most common cause of inflammatory arthritis in men, but has not previously been included in Global Burden of Disease (GBD) studies. As part of the GBD 2010 Study, the Musculoskeletal Disorders and Risk Factors Expert Group estimated the global burden of gout.

METHODS

The American Rheumatism Association 1977 case definition of primary gout was used in the study. A series of systematic reviews were conducted to gather the age-specific and sex-specific epidemiological data for gout prevalence, incidence, mortality risk and duration. Two main disabling sequelae of gout were identified; acute episode gout and chronic polyarticular gout, and used in the surveys to collect data to derive disability weights. The epidemiological data together with disability weights were then used to calculate years of life lived with disability (YLDs) for gout, for 1990 and 2010. No evidence of cause-specific mortality associated with gout was found. Gout disability-adjusted life years (DALYs), therefore, have the same value as YLDs.

RESULTS

Global prevalence of gout was 0.08% (95% uncertainty interval (UI) 0.07 to 0.08). DALYs increased from 76 000 (95% UI 48 to 112) in 1990 to 114 000 (95% UI 72 to 167) in 2010. Out of all 291 conditions studied in the GBD 2010 Study, gout ranked 138th in terms of disability as measured by YLDs, and 173rd in terms of overall burden (DALYs).

CONCLUSIONS

The burden of gout is rising. With increasing ageing populations globally, this evidence is a significant prompt to optimise treatment and management of gout at individual, community and national levels.

The global burden of musculoskeletal conditions for 2010: an overview of methods

The objective of this paper is to provide an overview of methods used for estimating the burden from musculoskeletal (MSK) conditions in the Global Burden of Diseases 2010 study. It should be read in conjunction with the disease-specific MSK papers published in Annals of Rheumatic Diseases. Burden estimates (disability-adjusted life years (DALYs)) were made for five specific MSK conditions: hip and/or knee osteoarthritis (OA), low back pain (LBP), rheumatoid arthritis (RA), gout and neck pain, and an 'other MSK conditions' category. For each condition, the main disabling sequelae were identified and disability weights (DW) were derived based on short lay descriptions. Mortality (years of life lost (YLLs)) was estimated for RA and the rest category of 'other MSK', which includes a wide range of conditions such as systemic lupus erythematosus, other autoimmune diseases and osteomyelitis. A series of systematic reviews were conducted to determine the prevalence, incidence, remission, duration and mortality risk of each condition. A Bayesian meta-regression method was used to pool available data and to predict prevalence values for regions with no or scarce data. The DWs were applied to prevalence values for 1990, 2005 and 2010 to derive years lived with disability. These were added to YLLs to quantify overall burden (DALYs) for each condition. To estimate the burden of MSK disease arising from risk factors, population attributable fractions were determined for bone mineral density as a risk factor for fractures, the occupational risk of LBP and elevated body mass index as a risk factor for LBP and OA. Burden of Disease studies provide pivotal guidance for governments when determining health priority areas and allocating resources. Rigorous methods were used to derive the increasing global burden of MSK conditions.

Allopurinol, benzbromarone, or a combination in treating patients with gout: analysis of a series of outpatients

Objective. To profile a sample of gouty patients treated with allopurinol, benzbromarone, or a combination of these two drugs and to describe the impact of this therapy in reducing uric acid levels. Methods. An observational, transversal study was performed. We evaluated 48 patients diagnosed with gout who were seen at the Outpatient Rheumatology Clinic of the Federal University of Paraná between January 2009 and November 2010. Clinical data, creatinine serum levels, and basal and posttreatment levels of serum urates, transaminases, and bilirubins were recorded. Uric acid levels were measured in a 24-hour urine sample. Patients were divided into three groups: patients given only allopurinol (A), only benzbromarone (B), and both in combined therapy (A + B). Results. The average age of these patients was 56.6 ± 11.4 years, varying from 35 to 81 years. The entire patient group experienced a significant drop in serum urate levels, from 8.5 ± 1.8 mg/dL (0.472 ± 0.1 mmol/L) to 6.7 ± 2.1 mg/dL (0.372 ± 0.116 mmol/L) (P < 0.001), regardless of the prescribed medication. The number of patients taking both drugs whose serum uric acid values fell within normal range (men <7 mg/dL (0.38 mmol/L) and women <6 mg/dL (0.33 mmol/L)) was 85.7% (6/7) while this value for the group taking benzbromarone alone was 75% (3/4) and for the group taking allopurinol alone this number was 51.8% (14/27). Conclusions. The therapeutic combination of benzbromarone and allopurinol significantly decreased serum urate levels in patients with gout when compared to individual use of each of these agents. This finding is especially important in treating patients who cannot control hyperuricemia with monotherapy. Benzbromarone alone or in combination with allopurinol has an important clinical role in controlling hyperuricemia in patients with gout.

Purine derivate content and amino acid profile in larval stages of three edible insects

BACKGROUND

Considering their high content of protein, insects are a valuable alternative protein source. However, no evaluation of their purine content has so far been done. High content of purine derivates may lead to the exclusion of such food from the diet of people with specific diseases. The aim of this study was to analyse the content of selected purine derivates and amino acid profile in the three insect species most often used for entomophagy in Europe and compare them with the purine content in egg white and chicken breast.

RESULTS

The content of individual purine derivates and their total content were significantly dependent on insect species. The purine content in all three species was significantly higher (P < 0.05) than in egg white, but some values were significantly lower (P < 0.05) than in chicken breast. The total protein content was 548.9 g kg(-1) dry matter (DM) in mealworm (Tenebrio molitor), 551.6 g kg(-1) DM in superworm (Zophobas atratus) and 564.9 g kg(-1) DM in cricket (Gryllus assimilis).

CONCLUSION

Larvae of mealworm and superworm are protein-rich and purine-low meat alternatives. In contrast, cricket nymphs are protein-rich and purine-rich and cannot be recommended for people with hyperuricemia or gout.

As compared to allopurinol, urate-lowering therapy with febuxostat has superior effects on oxidative stress and pulse wave velocity in patients with severe chronic tophaceous gout

We prospectively evaluated whether an effective 12-month uric acid-lowering therapy (ULT) with the available xanthine oxidase (XO) inhibitors allopurinol and febuxostat in patients with chronic tophaceous gout has an impact on oxidative stress and/or vascular function. Patients with chronic tophaceous gout who did not receive active ULT were included. After clinical evaluation, serum uric acid levels (SUA) and markers of oxidative stress were measured, and carotid-femoral pulse wave velocity (cfPWV) was assessed. Patients were then treated with allopurinol (n = 9) or with febuxostat (n = 8) to target a SUA level ≤ 360 μmol/L. After 1 year treatment, the SUA levels, markers of oxidative stress and the cfPWV were measured again. Baseline characteristics of both groups showed no significant differences except a higher prevalence of moderate impairment of renal function (estimated glomerular filtration rate <60 ml/min) in the febuxostat group. Uric acid lowering with either inhibitors of XO resulted in almost equally effective reduction in SUA levels. The both treatment groups did not differ in their baseline cfPWV (allopurinol group: 14.1 ± 3.4 m/s, febuxostat group: 13.7 ± 2.7 m/s, p = 0.80). However, after 1 year of therapy, we observed a significant cfPWV increase in the allopurinol group (16.8 ± 4.3 m/s, p = 0.001 as compared to baseline), but not in the febuxostat patients (13.3 ± 2.3 m/s, p = 0.55). Both febuxostat and allopurinol effectively lower SUA levels in patients with severe gout. However, we observed that febuxostat also appeared to be beneficial in preventing further arterial stiffening. Since cardiovascular events are an important issue in treating patients with gout, this unexpected finding may have important implications and should be further investigated in randomized controlled trials.

Gout impacts on function and health-related quality of life beyond associated risk factors and medical conditions: results from the KING observational study of the Italian Society for Rheumatology (SIR)

Introduction

Gout is the most prevalent arthritis and significantly impacts on function and quality of life. Given that gout associates with disabling comorbid conditions, it is not clear whether such a complex of diseases accounts for the increased disability or if gout may play a role by itself. This study aims to evaluate the specific influence of gout and disease-related features on functional disability and health-related quality of life (HRQoL) in patients with gout followed in rheumatology clinics.

Methods

A random sample of patients was drawn from clinical registries of 30 rheumatology clinics across Italy. Sociodemographic, general health and gout-specific variables were collected. Functional disability and HRQoL were assessed by the health assessment questionnaire (HAQ) and the Physical and Mental Component Summary scores (PCS and MCS) of the Short Form-36 (SF-36). Crude and adjusted ordinal logistic and linear regression models were applied to investigate the specific contribution of different variables on HAQ and SF-36 scores. Results are presented as odds ratio (OR) or mean difference (MD) and 95% confidence intervals.

Results

Out of 446 patients with gout, 90% were males with a mean age of 63.9 years and median disease duration of 3.8 years; the majority of patients were overweight or obese, and with several comorbidities; 21.1% showed at least moderate disability; the PCS score was significantly lower than expected age- and gender-matched samples in the general population, while MCS score was not. After adjusting for potential sociodemographic and general-health confounders, gout-specific variables significantly impacted on HAQ, including polyarticular involvement OR 3.82 (1.63, 8.95), presence of tophi OR 1.92 (1.07, 3.43) and recent attacks OR 2.20 (1.27, 3.81). Consistent results were found for PCS. The impairment of PCS compared to the general population was limited to patients with features of chronic gout. MCS was only affected by recent attacks (MD -2.72 [-4.58, -0.86]) and corticosteroid treatment (-3.39 [-5.30,-1.48]).

Conclusions

The data from the KING study confirm that gout impacts on disability and provide evidence for an independent association of gout and gout-related features with functional outcome and HRQoL. This result supports the need to improve specific treatment in gout.

Multinational evidence-based recommendations for the diagnosis and management of gout: integrating systematic literature review and expert opinion of a broad panel of rheumatologists in the 3e initiative

We aimed to develop evidence-based multinational recommendations for the diagnosis and management of gout. Using a formal voting process, a panel of 78 international rheumatologists developed 10 key clinical questions pertinent to the diagnosis and management of gout. Each question was investigated with a systematic literature review. Medline, Embase, Cochrane CENTRAL and abstracts from 2010-2011 European League Against Rheumatism and American College of Rheumatology meetings were searched in each review. Relevant studies were independently reviewed by two individuals for data extraction and synthesis and risk of bias assessment. Using this evidence, rheumatologists from 14 countries (Europe, South America and Australasia) developed national recommendations. After rounds of discussion and voting, multinational recommendations were formulated. Each recommendation was graded according to the level of evidence. Agreement and potential impact on clinical practice were assessed. Combining evidence and clinical expertise, 10 recommendations were produced. One recommendation referred to the diagnosis of gout, two referred to cardiovascular and renal comorbidities, six focused on different aspects of the management of gout (including drug treatment and monitoring), and the last recommendation referred to the management of asymptomatic hyperuricaemia. The level of agreement with the recommendations ranged from 8.1 to 9.2 (mean 8.7) on a 1-10 scale, with 10 representing full agreement. Ten recommendations on the diagnosis and management of gout were established. They are evidence-based and supported by a large panel of rheumatologists from 14 countries, enhancing their utility in clinical practice.

Effect of Genetic Polymorphisms on Development of Gout

Objective.

To validate the association between genetic polymorphisms and gout in Japanese patients, and to investigate the cumulative effects of multiple genetic factors on the development of gout.

Methods.

Subjects were 153 Japanese male patients with gout and 532 male controls. The genotypes of 11 polymorphisms in the 10 genes that have been indicated to be associated with serum uric acid levels or gout were determined. The cumulative effects of the genetic polymorphisms were investigated using a weighted genotype risk score (wGRS) based on the number of risk alleles and the OR for gout. A model to discriminate between patients with gout and controls was constructed by incorporating the wGRS and clinical factors. C statistics method was applied to evaluate the capability of the model to discriminate gout patients from controls.

Results.

Seven polymorphisms were shown to be associated with gout. The mean wGRS was significantly higher in patients with gout (15.2 ± 2.01) compared to controls (13.4 ± 2.10; p < 0.0001). The C statistic for the model using genetic information alone was 0.72, while the C statistic was 0.81 for the full model that incorporated all genetic and clinical factors.

Conclusion.

Accumulation of multiple genetic factors is associated with the development of gout. A prediction model for gout that incorporates genetic and clinical factors may be useful for identifying individuals who are at risk of gout.

Serum uric acid and gout: from the past to molecular biology

OBJECTIVES

This review will briefly present the epidemiology and risk factors of gout, with a focus on recent advances.

METHODS

Key papers for inclusion were identified by a PubMed search, and articles were selected according to their relevance for the topic, according to authors' judgment.

RESULTS AND CONCLUSIONS

Gout therapy has remained very much unchanged for the last 50 years, but recently we have seen the approval of another gout treatment: the xanthine oxidase inhibitor febuxostat, and several new drugs are now in the late stages of clinical testing. Together with our enhanced level of understanding of the pathophysiology of the inflammatory process involved, we are entering a new era for the treatment of gout.

Cervical cord compression due to intradiscal gouty tophus: brief report

STUDY DESIGN

We describe an unusual cause of myelopathy with a discussion of similar cases previously reported in the literature.

OBJECTIVE

To report a case of myelopathy due to intradiscal gouty tophus.

SUMMARY OF BACKGROUND DATA

Spinal involvement in gout is uncommon. Cervical spinal cord compression caused by gout is particularly rare.

METHODS

We report the case of a 71-year-old man with a history of hyperuricemia gout. Spastic quadriparesis developed for more than 4 months. Magnetic resonance image of the cervical spine revealed a herniated cervical disc at the C3-C4 level. Anterior discectomy was performed. Intradiscal chalky white granular material was found during surgery.

RESULTS

Histological examination of the surgical specimen demonstrated a gouty tophus. The patient regained strength in all extremities in the postoperative period and required rehabilitation treatment.

CONCLUSION

Spinal gout should be considered in all patients presenting myelopathy and history of gout. When progressive neurological symptoms develop, surgical decompression can provide a satisfactory outcome.

Inhibition of monosodium urate crystal-induced inflammation by scopoletin and underlying mechanisms

The present study determined the anti-inflammatory activity of scopoletin in gout air pouch model and revealed the underlying mechanisms by in vitro assays. Monosodium urate (MSU) crystal-induced inflammation in mouse air pouch model, an experimental model for acute gout, was used to assess the efficacy of scopoletin. The neutrophil and mononuclear phagocyte numbers and MPO levels were increased significantly six hours after MSU crystal injection into the air pouch, whereas these changes were inhibited substantially upon scopoletin (100 and 200mg/kg, i.p.) treatment. To get insight into the underlying mechanisms, the in vitro studies were performed to investigate the effects of scopoletin on activation of macrophages and resultant production of inflammatory mediators. The secretions of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), prostaglandin E(2) (PGE(2)) and nitric oxide (NO) were elevated in MSU crystal-stimulated RAW 264.7 cells, and scopoletin (30-300 μM) suppressed the production of all mediators. Moreover, RT-PCR assay and western blot analysis indicated that scopoletin regulated the transcriptional level of these mediators via suppression of NF-κB activation and blockade of MAPK signal pathway. Thus, the results clearly indicated that scopoletin inhibited the monosodium urate crystal-induced inflammation both in vivo and in vitro. In combination with our previous findings that scopoletin shows hypouricemic, anti-angiogenesis and pro-apoptotic activities, this compound may be a potential agent for gout therapy and could serve as a structural base for developing new drugs.

Disability due to gouty arthritis

PURPOSE OF REVIEW

Disability, or activity limitation, is a common problem in patients with gout. This study explores recent studies examining the nature and extent of disability in gout and addresses the merits and limitations of current self-reported measures of disability.

RECENT FINDINGS

Gout has a significant impact on patients' ability to perform normal self-care activities, recreational and social activities, and work. Comparative studies indicate that gout patients' physical functioning is strongly reduced and comparable to those with other severe rheumatic conditions. Moreover, gout has been shown to result in substantial work absence and reduced productivity. However, few studies have thoroughly examined the concept of disability in gout. Additionally, assessment of disability due to gout still seems particularly challenging and it is unclear whether current measurement instruments are sufficiently valid and accurate.

SUMMARY

Gout-related disability is an underestimated and understudied problem. More qualitative and quantitative studies are needed that examine the concept of disability in gout and its impact on patients' lives, both during and between disease flares. Moreover, future studies should try to identify gout-specific disability issues and examine the relevance and comprehensiveness of existing measures to further improve the assessment of disability in gout.

Anti-hyperuricemic and nephroprotective effects of Modified Simiao Decoction in hyperuricemic mice

ETHNOPHARMACOLOGICAL RELEVANCE

Modified Simiao Decoction (MSD), based on clinical experience, has been used for decades and famous for its efficiency in treating hyperuricemic and gouty diseases.

AIM OF THE STUDY

To investigate the effects of MSD on anti-hyperuricemic and nephroprotective effects are involved in potassium oxonate-induced hyperuricemic mice.

MATERIALS AND METHODS

The effects of MSD were investigated in hyperuricemic mice induced by potassium oxonate. MSD were fed to hyperuricemic mice daily at a dose of 0.45, 0.90, 1.80 g/kg for 10 days, and allopurinol (5mg/kg) was given as a positive control. Serum and urine levels of uric acid and creatinine, and fractional excretion of uric acid (FEUA) were determined by colorimetric method. Its nephroprotective effects were evaluated by determining a panel of oxidative stress markers after the intervention in hyperuricemic mice. Simultaneously, protein levels of urate transporter 1 (URAT1) and organic anion transporter 1 (OAT1) in the kidney were analyzed by Western blotting.

RESULTS

MSD could inhibit XOD activities in serum and liver, decrease levels of serum uric acid, serum creatinine and BUN, and increased levels of urine uric acid, urine creatinine, FEUA dose-dependently through down-regulation of URAT1 and up-regulation of OAT1 protein expressions in the renal tissue of hyperuricemic mice. It also effectively reversed oxonate-induced alterations on renal MDA levels and SOD activities in this model.

CONCLUSION

MSD processes uricosuric and nephroprotective actions by regulating renal urate transporters and enhancing antioxidant enzymes activities to improve renal dysfunction in hyperuricemic mice.

Risk factors for gout developed from hyperuricemia in China: a five-year prospective cohort study

The aim of the study was to investigate the factors that promote the development of gout in Chinese patients with hyperuricemia. Chinese cohort with 659 patients with hyperuricemia who had no history of gout at base line had been followed up for 5 years. The baseline data of the general states (gender, age, occupation and education level), lifestyle and behavior (smoking, drinking, and diet), the major chronic diseases (diabetes and hypertension), family history and gout attacks, physical examination (height, weight and blood pressure), and blood parameters (creatinine, urea nitrogen, triglycerides, total cholesterol and high-density lipoprotein cholesterol) were recorded before the follow-up. Over the five-year period, 75 hyperuricemia patients developed gout. In the logistic regression model, shrimp intake and shell intake were the risk factors (P = 0.038 and P < 0.001, respectively) and, combined with diabetes, also served as risk factor for gout developed from hyperuricemia, with relative risk (RR) of 2.571 (95 % confidence interval (95 % CI), 1.110-5.953), and females served as protective factors of gout, with RR of 0.113 (95 % CI, 0.041-0.312, referred to male). We identified that shrimp intake and shell intake, combined with diabetes, were the independent risk factors, and females served as protective factors of gout in those suffering from hyperuricemia in coast regions of Shandong province, China.