A prospective study of gout in New Zealand Maoris

Building capacity to conduct genetic epidemiology research on hyperuricaemia and gout in an Indigenous community in Guam

Background

Gout, the most common inflammatory arthritis disease, and hyperuricaemia onset are influenced by environmental and genetic factors. We sought to investigate these factors in an Indigenous community in Guam.

Methods

In this cross-sectional study, the University of Guam led the qualitative inquiry with the native community, training (pre-screening of participants, data collection methods, and biospecimen handling), study implementation (outreach and recruitment, data collection, and DNA extraction and quantification), and qualitative and epidemiologic data analyses. Recruitment targets were based on demographic representation in current census data. The University of Otago collaborated on ethics guidance, working with Indigenous communities, and led the genetic sequencing and genetic data analysis. Participants were recruited in Guam from Fall 2019 to Spring 2022.

Results

Of the 359 participants, most self-identified as Native CHamorus (61.6%) followed by Other Micronesians (22.0%), and Filipinos (15.6%). The prevalence of metabolic conditions from highest to lowest were obesity (55.6%), hyperuricaemia (36.0%), hypertension (27.8%), gout (23.0%), diabetes (14.9%), cardiovascular disease (8.4%), kidney disease (7.3%), and liver disease (3.4%). Compared to Filipinos and Other Micronesians, significantly more CHamorus had hyperuricaemia (42.1% versus 26.8% in Filipinos and 25.3% in Other Micronesians), gout (28.5% versus 21.4% and 8.9%), diabetes (19.5% versus 8.9% and 6.3%), and hypertension (33.9% versus 19.6% and 16.5%).

Conclusions

We estimated the prevalence of metabolic conditions, especially gout and hyperuricaemia, and found statistical differences among major ethnic groups in Guam, all while obtaining the Indigenous community's feedback on the genetic study and building gout research capacity. The results of ongoing genetic sequencing will be used to understand molecular causes of gout in Guam.

Reference range of serum uric acid and prevalence of hyperuricemia: a cross-sectional study from baseline data of ELSA-Brasil cohort

Background

Most of the few studies that have established reference ranges for serum uric acid (SUA) have not taken into account factors which may interfere with its levels and followed rigorous laboratory quality standards. The aim of this study was to establish reference ranges for SUA and determine the prevalence of hyperuricemia.

Method

Cross-sectional study including 15,100 participants (all sample) aged 35 to 74 years from baseline data of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), a multicentric cohort of volunteer civil servants from five universities and one research institute located in different regions of Brazil. It was established a reference sample excluding participants with factors that directly influence SUA levels: glomerular filtration rate lower than 60 ml/min, excessive alcohol intake, use of diuretics, aspirin, estrogen or urate-lowering therapy. SUA was measured using the uricase method and following rigorous international quality standards. Reference ranges were defined as values between percentiles 2.5 (P2.5) and 97.5 (P97.5) of SUA distribution in the reference sample, stratified by sex. Hyperuricemia was defined as SUA ≥ 7 mg/100 ml in the all sample.

Results

The reference sample was composed of 10,340 individuals (55.3% women, median age 50 years). Reference ranges (P2.5 to P97.5) for SUA were: 4.0 to 9.2 mg/100 ml for men and 2.8 to 6.9 mg/100 ml for women. Sex was a major determinant for SUA levels (median [IQR], mg/100 ml: 6.1 [5.3–7.0] for men versus 4.5 [3.9–5.3] for women, p < 0.001). Higher levels of SUA were found in patients with higher BMI. Higher age had (a modest) influence only for women. The prevalence of hyperuricemia for all sample (N = 15,100) was 31.9% (95% confidence interval [CI] 30.8–33.0%) in men and 4.8% (95% CI 4.3–5.3%) in women.

Conclusion

SUA reference ranges were 4.0 to 9.2 mg/100 ml for men and 2.8 to 6.9 mg/100 ml for women. Prevalence of hyperuricemia was 31.9% in men and 4.8% in women. Updated SUA reference ranges and prevalence of hyperuricemia are higher nowadays and might be used to guide laboratories and the screening for diseases related to SUA.

Gout and hyperuricaemia in the USA: prevalence and trends

Objectives

Several recent observations have suggested that the prevalence of gout may be increasing worldwide, but there are no recent data from the USA. We analysed the prevalence of hyperuricaemia and gout in the US population from 2007–08 to 2015–16.

Methods

We studied adults ⩾20 years of age from the National Health and Nutrition Examination Survey from 2007–08 to 2015–16. Persons with gout were identified from the home interview question ‘Has a doctor or other health professional ever told you that you had gout?’ Hyperuricaemia was defined as a serum urate level >0.40 mmol/l (6.8 mg/dl) (supersaturation levels at physiological temperatures and pH).

Results

In 2015–16, the overall prevalence of gout among US adults was 3.9%, corresponding to a total affected population of 9.2 million. Hyperuricaemia (>0.40 mmol/l or 6.8 mg/dl) was seen in 14.6% of the US population (estimated 32.5 million individuals). No significant trends were identified in the age-adjusted prevalence of gout and hyperuricaemia. Statistical comparisons between 2007–08 and 2015–16 age-adjusted rates were not significant.

Conclusion

While the age-adjusted prevalence of gout and hyperuricaemia has remained unchanged in the most recent decade from 2007–08 to 2015–16, the estimated total number of persons with self-reported gout has increased from 8.3 million to 9.2 million. The age-adjusted prevalence of hyperuricaemia has declined slightly, but the total number of affected individuals is virtually identical (32.5 million in 2015–16 compared with 32.1 million in 2007–08).

Dose-response relationship between higher serum calcium level and higher prevalence of hyperuricemia: A cross-sectional study

The aim of the study was to examine the relationship between serum calcium (Ca) levels and the prevalence of hyperuricemia (HU).The data included in this analysis were extracted from a population-based study conducted at the Xiangya Hospital Health Management Centre. Serum Ca levels were measured using the Arsenazo III method. HU was defined as the uric acid ≥416 μmol/L for male subjects, and ≥360 μmol/L for female subjects. The association between serum Ca levels and the prevalence of HU was evaluated using logistic and spline regression.The present study included a total of 6337 subjects. The overall prevalence of HU for the target population was 17.5%. Compared with the lowest quintile, the odds ratios adjusted by age, sex, body mass index, smoking, and drinking for HU were 1.51 [95% confidence interval (CI): 1.20-1.91], 1.43 (95% CI: 1.13-1.82), 2.02 (95% CI: 1.61-2.54), and 2.54 (95% CI: 2.02-3.18) for the second, third, fourth, and fifth quintiles of serum Ca levels, respectively (P for trend <.001), and a positive dose-response relationship was observed. Similar results were observed for men and women, respectively. The findings were not materially altered by the adjustment for further potential confounders.Subjects with higher serum Ca levels are subject to a higher prevalence of HU in a dose-response relationship manner.

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

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

Characterization of indigenous community engagement in arthritis studies conducted in Canada, United States of America, Australia and New Zealand

BACKGROUND

Research adhering to community engagement processes leads to improved outcomes. The level of Indigenous communities' engagement in rheumatology research is unknown.

OBJECTIVE

To characterize the frequency and level of community engagement reporting in arthritis studies conducted in Australia (AUS), Canada (CAN), New Zealand (NZ) and the United States of America (USA).

METHODS

Studies identified through systematic reviews on topics of arthritis epidemiology, disease phenotypes and outcomes, health service utilization and mortality in Indigenous populations of AUS, CAN, NZ and USA, were evaluated for their descriptions of community engagement. The level of community engagement during inception, data collection and results interpretation/dissemination stages of research was evaluated using a custom-made instrument, which ranked studies along the community engagement spectrum (i.e. inform-consult-involve-collaborate-empower). Meaningful community engagement was defined as involving, collaborating or empowering communities. Descriptive analyses for community engagement were performed and secondary non-parametric inferential analyses were conducted to evaluate the possible associations between year of publication, origin of the research idea, publication type and region of study; and meaningful community engagement.

RESULTS

Only 34% (n = 69) of the 205 studies identified reported community engagement at ≥ 1 stage of research. Nearly all studies that engaged communities (99% (n = 68)) did so during data collection, while only 10% (n = 7) did so at the inception of research and 16% (n = 11) described community engagement at the results' interpretation/dissemination stage. Most studies provided community engagement descriptions that were assessed to be at the lower end of the spectrum. At the inception of research stage, 3 studies reported consulting communities, while 42 studies reported community consultation at data collection stage and 4 studies reported informing or consulting communities at the interpretation/dissemination of results stage. Only 4 studies described meaningful community engagement through all stages of the research. Inferential statistics identified that studies with research ideas that originated from the Indigenous communities involved were significantly more associated with achieving meaningful community engagement.

CONCLUSIONS

The reporting of Indigenous community engagement in published arthritis studies is limited in frequency and is most frequently described at the lower end of the community engagement spectrum. Processes that support meaningful community engagement are to be promoted.

Serum Uric Acid and the Risk of Incident and Recurrent Gout: A Systematic Review

OBJECTIVE

Lowering serum uric acid (SUA) levels can essentially cure gout; however, this is not widely practiced. To summarize epidemiologic evidence related to this causal link, we conducted a systematic review of the published literature reporting the association between SUA level and incident and recurrent gout (i.e., gout flares).

METHODS

We systematically searched Medline, EMBASE, and the Cochrane Database of Systematic Reviews using separate search strategies for incident gout and recurrent gout. We screened 646 abstracts to identify 8 eligible articles reporting gout incidence and 913 abstracts to identify 18 articles reporting recurrent gout.

RESULTS

For both gout incidence and recurrence, a graded trend was observed where the risk was increased with higher SUA levels. Gout incidence rates per 1000 person-years from population-based studies ranged from 0.8 (SUA ≤ 6 mg/dl) to 70.2 cases (SUA ≥ 10 mg/dl). Recurrent gout risk in clinical cohorts ranged from 12% (SUA ≤ 6 mg/dl) to 61% (SUA ≥ 9 mg/dl) among those receiving urate-lowering therapy (ULT), and 3.7% (SUA 6-7 mg/dl) to 61% (SUA > 9.3 mg/dl) after successful ULT. Retrospective database studies also showed a graded relationship, although the strength of the association was weaker. Studies reporting mean flares or time-to-flare according to SUA showed similar findings.

CONCLUSION

This systematic review confirms that higher SUA levels are associated with increased risk of incident and recurrent gout in a graded manner. Although few prospective cohorts have evaluated incident and recurrent gout according to SUA, the existing evidence underscores the need to treat to SUA targets, as recommended by the American College of Rheumatology and the European League Against Rheumatism.

Association between high-sensitivity C-reactive protein and hyperuricemia

The aim of the study was to examine the cross-sectional association between high-sensitivity C-reactive protein (hsCRP) and hyperuricemia (HU). The hsCRP was measured by latex turbidity method. Uric acid was detected on Beckman Coulter AU 5800. HU was defined as uric acid ≥416 μmol/L for the male population and ≥360 μmol/L for the female population. A multivariable logistic analysis model was applied to test the association after adjusting for a number of potential confounding factors. A total of 1935 subjects were included in this study. According to the multivariable regression model, the relative odds of the prevalence of HU were increased by 0.56 times in the third quintile (OR 1.56, 95 % CI 1.03-2.38, P = 0.04), 0.55 times in the fourth quintile (OR 1.55, 95 % CI 1.01-2.36, P = 0.04) and 0.96 times in the fifth quintile (OR 1.96, 95 % CI 1.29-2.98, P < 0.01) of hsCRP comparing with the lowest quintile, and P for trend was smaller than 0.01. In the male population, a positive association existed in the highest quintile of hsCRP (OR 1.66, 95 % CI 1.04-2.66, P = 0.04), and P for trend was 0.07. In the female population, the multivariable-adjusted ORs (95 % CI) of HU in the fourth and fifth quintile of hsCRP were 3.02 (95 % CI 1.09-8.35, P = 0.03) and 3.66 (95 % CI 1.36-9.89, P = 0.01), respectively, and P for trend was smaller than 0.01. The findings of this cross-sectional study suggest that the hsCRP level is positively associated with the prevalence of HU. Level of evidence Cross-sectional study, Level III.

Association between Dietary Magnesium Intake and Hyperuricemia

Objective

To examine the cross-sectional associations between dietary magnesium (Mg) intake and hyperuricemia (HU).

Methods

5168 subjects were included in this study. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire. Hyperuricemia (HU) was defined as uric acid ≥ 416 μmol/L for male population and ≥ 360 μmol/L for female. A multivariable logistic analysis model was applied to test the associations after adjusting a number of potential confounding factors.

Results

The relative odds of the overall prevalence of HU were decreased by 0.57 times in the fourth quintile of Mg intake (OR 0.57, 95% CI 0.35–0.94) and 0.55 times in the fifth quintile (OR 0.55, 95% CI 0.30–1.01) comparing with the lowest quintile, and P for trend was 0.091. The results of multivariable linear regression also suggested a significant inverse association between serum uric acid and Mg intake (β = -0.028, P = 0.022). For male, the relative odds of HU were decreased by 0.62 times in the third quintile of Mg intake (OR 0.62, 95% CI 0.40–0.97), 0.40 times in the fourth quintile (OR 0.40, 95% CI 0.23–0.72) and 0.35 times in the fifth quintile (OR 0.35, 95% CI 0.17–0.71) comparing with the lowest quintile, and P for trend was 0.006. Multivariable adjusted inverse association was also existed between serum uric acid and Mg intake in male population (β = -0.061, P = 0.002). However, no significant association was observed between dietary Mg intake and HU for female.

Conclusions

The findings of this cross-sectional study indicated that dietary Mg intake is inversely associated with HU, independent of some major confounding factors. In addition, this association remains valid for the male subgroup, but not for the female subgroup.

Level of Evidence

LevelIII, cross-sectional study.

Global epidemiology of gout: prevalence, incidence and risk factors

Gout is a crystal-deposition disease that results from chronic elevation of uric acid levels above the saturation point for monosodium urate (MSU) crystal formation. Initial presentation is mainly severely painful episodes of peripheral joint synovitis (acute self-limiting 'attacks') but joint damage and deformity, chronic usage-related pain and subcutaneous tophus deposition can eventually develop. The global burden of gout is substantial and seems to be increasing in many parts of the world over the past 50 years. However, methodological differences impair the comparison of gout epidemiology between countries. In this comprehensive Review, data from epidemiological studies from diverse regions of the world are synthesized to depict the geographic variation in gout prevalence and incidence. Key advances in the understanding of factors associated with increased risk of gout are also summarized. The collected data indicate that the distribution of gout is uneven across the globe, with prevalence being highest in Pacific countries. Developed countries tend to have a higher burden of gout than developing countries, and seem to have increasing prevalence and incidence of the disease. Some ethnic groups are particularly susceptible to gout, supporting the importance of genetic predisposition. Socioeconomic and dietary factors, as well as comorbidities and medications that can influence uric acid levels and/or facilitate MSU crystal formation, are also important in determining the risk of developing clinically evident gout.

Determinants of the prevalence of gout in the general population: a systematic review and meta-regression

Studies on the occurrence of gout show a large range in estimates. However, a clear insight into the factors responsible for this variation in estimates is lacking. Therefore, our aim was to review the literature on the prevalence and incidence of gout systematically and to obtain insight into the degree of and factors contributing to the heterogeneity. We searched MEDLINE, EMBASE, and Web of Science (January 1962 to July 2012) to identify primary studies on the prevalence and incidence of gout in the general population. Data were extracted by two persons on sources of clinical heterogeneity, methodological heterogeneity, and variation in outcome reporting. Meta-analysis and meta-regression analysis were performed for the prevalence of gout. Of 1,466 articles screened, 77 articles were included, of which 71 reported the prevalence and 12 the incidence of gout. The pooled prevalence (67 studies; N = 12,226,425) based on a random effects model was 0.6% (95% CI 0.4; 0.7), however there was a high level of heterogeneity (I(2) = 99.9%). Results from a mixed-effects meta-regression model indicated that age (p = 0.019), sex (p < 0.001), continent (p < 0.001), response rate (p = 0.016), consistency in data collection (p = 0.002), and case definition (p < 0.001) were significantly associated with gout prevalence and jointly accounted for 88.7% of the heterogeneity. The incidence in the total population ranged from 0.06 to 2.68 per 1,000 person-years. In conclusion, gout is a common disease and the large variation in the prevalence data on gout is explained by sex, continent on which the study was performed, and the case definition of gout.

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.

Hyperuricaemia in the Pacific: why the elevated serum urate levels?

Pacific Island populations, particularly those of Polynesian descent, have a high prevalence of hyperuricaemia and gout. This is due to an inherently higher urate level among these populations with a demonstrated genetic predisposition. While an excess of urate can cause pathology, urate is also important for human health. It has been implicated as an antioxidant, has a neuroprotective role and is involved in innate immune responses. This paper provides a brief review of urate levels worldwide, with a particular focus on island Southeast Asia and the Pacific. We then present possible evolutionary explanations for the elevated serum urate levels among Pacific populations in the context of the physiological importance of urate and of the settlement history of the region. Finally, we propose that ancestry may play a significant role in hyperuricaemia in these populations and that exposure to malaria prior to population expansion into the wider Pacific may have driven genetic selection for variants contributing to high serum urate.

National prevalence of gout derived from administrative health data in Aotearoa New Zealand

OBJECTIVE

Previous small studies in Aotearoa New Zealand have indicated a high prevalence of gout. This study sought to determine the prevalence of gout in the entire Aotearoa New Zealand population using national-level health data sets.

METHODS

We used hospitalization and drug dispensing claims for allopurinol and colchicine for the entire Aotearoa New Zealand population from the Aotearoa New Zealand Health Tracker (ANZHT) to estimate the prevalence of gout in 2009, stratified by age, gender, ethnicity and socio-economic status (n = 4 295 296).

RESULTS

were compared with those obtained from an independent large primary care data set (HealthStat, n = 555 313). Results. The all-ages crude prevalence of diagnosed gout in the ANZHT population was 2.69%. A similar prevalence of 2.89% was observed in the HealthStat population standardized to the ANZHT population for age, gender, ethnicity and deprivation. Analysis of the ANZHT population showed that gout was more common in Māori and Pacific people [relative risk (RR) 3.11 and 3.59, respectively], in males (RR 3.58), in those living in the most socio-economically deprived areas (RR 1.41) and in those aged >65 years (RR >40) (P-value for all <0.0001). The prevalence of gout in elderly Māori and Pacific men was particularly high at >25%.

CONCLUSION

Applying algorithms to national administrative data sets provides a readily available method for estimating the prevalence of a chronic condition such as gout, where diagnosis and drug treatment are relatively specific for this disease. We have demonstrated high gout prevalence in the entire Aotearoa New Zealand population, particularly among Māori and Pacific people.

A cohort study comparing cardiovascular risk factors in rural Maori, urban Maori and non-Maori communities in New Zealand

OBJECTIVES

To understand health disparities in cardiovascular disease (CVD) in the indigenous Māori of New Zealand, diagnosed and undiagnosed CVD risk factors were compared in rural Māori in an area remote from health services with urban Māori and non-Māori in a city well served with health services.

DESIGN

Prospective cohort study.

SETTING

Hauora Manawa is a cohort study of diagnosed and previously undiagnosed CVD, diabetes and risk factors, based on random selection from electoral rolls of the rural Wairoa District and Christchurch City, New Zealand.

PARTICIPANTS

Screening clinics were attended by 252 rural Māori, 243 urban Māori and 256 urban non-Māori, aged 20-64 years.

MAIN OUTCOME MEASURES

The study documented personal and family medical history, blood pressure, anthropometrics, fasting lipids, insulin, glucose, HbA1c and urate to identify risk factors in common and those that differ among the three communities.

RESULTS

Mean age (SD) was 45.7 (11.5) versus 42.6 (11.2) versus 43.6 (11.5) years in rural Māori, urban Māori and non-Māori, respectively. Age-adjusted rates of diagnosed cardiac disease were not significantly different across the cohorts (7.5% vs 5.8% vs 2.8%, p=0.073). However, rural Māori had significantly higher levels of type-2 diabetes (10.7% vs 3.7% vs 2.4%, p<0.001), diagnosed hypertension (25.0% vs 14.9% vs 10.7%, p<0.001), treated dyslipidaemia (15.7% vs 7.1% vs 2.8%, p<0.001), current smoking (42.8% vs 30.5% vs 15.2%, p<0.001) and age-adjusted body mass index (30.7 (7.3) vs 29.1 (6.4) vs 26.1 (4.5) kg/m(2), p<0.001). Similarly high rates of previously undocumented elevated blood pressure (22.2% vs 23.5% vs 17.6%, p=0.235) and high cholesterol (42.1% vs 54.3% vs 42.2%, p=0.008) were observed across all cohorts.

CONCLUSIONS

Supporting integrated rural healthcare to provide screening and management of CVD risk factors would reduce health disparities in this indigenous population.

The epidemiology and treatment of gout

The development and expression of gout depends on three key steps: (1) chronic hyperuricemia, (2) the growth of monosodium urate (MSU) crystals, and (3) interaction between MSU crystals and the inflammatory system. Epidemiological studies have continued to improve our understanding of the environmental and genetic factors which influence chronic hyperuricemia and gout. The influence of obesity, alcohol, race, sex, age, and specific dietary components will be discussed below. The primary mechanism of hyperuricemia is insufficient renal clearance of uric acid which in turn is dependent on transport of uric acid in the proximal renal tubule. Knowledge of the transport mechanisms has improved understanding of the genetic influences on gout and is relevant to understanding of the effects of drugs which can increase or decrease renal uric acid clearance. The application of established principles of management including diagnosis through crystal identification, the gradual introduction of hypouricemic therapy with the use of prophylaxis to reduce the risk of flares, identification of a suitably low target of plasma urate, a progressive increase in therapy to achieve the target and taking steps to encourage good compliance, has the potential to improve outcomes for patients with this very common affliction. The potential role for new therapies will also be discussed.

Epidemiology of gout: an update

Gout is the most common inflammatory joint disease in men, characterised by formation of monosodium urate (MSU) crystals in the synovial fluid of joints and in other tissues. The epidemiology of gout provides us with the understanding of the disease distribution and its determinants. In an attempt to update the knowledge on the topic, more recent research reports on the descriptive epidemiology of gout are reviewed in this article. The review describes clinical characteristics and case definitions of gout, including the Rome and New York diagnosis criteria of gout, '1977 American Rheumatism Association (ARA) criteria' and the 10 key propositions of the European League Against Rheumatism (EULAR) recommendations. Gout incidence, prevalence, morbidity and mortality, geographical variation of the disease, relevant risk factors for both the occurrence and outcome of gout and trends of the disease over time are then described. Difficulties in obtaining the information and data reported are also discussed.

Risk factors for gout and prevention: a systematic review of the literature

PURPOSE OF REVIEW

Our objective was to perform a systematic review of risk factors and prevention of gout. We searched Medline for fully published reports in English using keywords including but not limited to 'gout', 'epidemiology', 'primary prevention', 'secondary prevention', 'risk factors'. Data from relevant articles meeting inclusion criteria were extracted using standardized forms.

RECENT FINDINGS

Of the 751 titles and abstracts, 53 studies met the criteria and were included in the review. Several risk factors were studied. Alcohol consumption increased the risk of incident gout, especially beer and hard liquor. Several dietary factors increased the risk of incident gout, including meat intake, seafood intake, sugar sweetened soft drinks, and consumption of foods high in fructose. Diary intake, folate intake, and coffee consumption were each associated with a lower risk of incident gout and in some cases a lower rate of gout flares. Thiazide and loop diuretics were associated with higher risk of incident gout and higher rate of gout flares. Hypertension, renal insufficiency, hypertriglyceridemia, hypercholesterolemia, hyperuricemia, diabetes, obesity, and early menopause were each associated with a higher risk of incident gout and/or gout flares.

SUMMARY

Several dietary risk factors for incident gout and gout flares are modifiable. Prevention and optimal management of comorbidities are likely to decreased risk of gout. Research in preventive strategies for the treatment of gout is needed.

Febuxostat: the evidence for its use in the treatment of hyperuricemia and gout

Introduction:

Gout is a common and disabling cause of arthritis in middle-aged and elderly populations, with its main predisposing factor being hyperuricemia (serum urate > 6.8 mg/dL). Options for treatment of chronic gout until 2008 were allopurinol, a xanthine oxidase inhibitor, and the group of drugs known as uricosurics that stimulate the renal excretion of uric acid. A proportion of patients, including some with chronic kidney disease and solid organ transplantations, could not be treated with the those therapies because of intolerance, drug interactions, or adverse events. Febuxostat is a nonpurine xanthine oxidase inhibitor, recently approved in Europe and the United States for the treatment of chronic gout.

Aim:

To review the clinical evidence (phase II and III studies) of the effectiveness and safety of febuxostat for treatment of hyperuricemia and gout.

Evidence review:

Febuxostat, at doses ranging from 40 to 240 mg/day, is efficacious in reducing serum urate in patients with hyperuricemia and gout, comparing favorably with fixed doses of allopurinol in that respect. Early safety signals with respect to liver test abnormalities and cardiovascular outcomes have not been confirmed in recent large prospective trials but need to be further monitored.

Clinical potential:

Given its low cost and extensive clinical experience, allopurinol will likely remain the first-line drug for management of hyperuricemia and gout. Febuxostat may provide an important option in patients unable to use allopurinol, those with very high serum urate levels, or in the presence of refractory tophi.

Genetics and experimental models of crystal-induced arthritis. Lessons learned from mice and men: is it crystal clear?

PURPOSE OF REVIEW

We examine the major genes in mice and humans involved in the pathogenesis of monosodium urate, calcium pyrophosphate dihydrate and hydroxyapatite crystal-induced arthritis.

RECENT FINDINGS

Several genetic causes of renal disease associated with hyperuricemia and gout provide insight into genes involved in renal urate handling. Mutations or polymorphisms in exons 4 and 5 and intron 4 of urate transporter 1 may be independent genetic markers of hyperuricemia and gout. Genetic analysis supports the role of ANKH mutations in calcium pyrophosphate dihydrate-induced arthritis. ANKH gain-of-function mutations were confirmed by functional studies; however, the crystals formed in ATD5 cells were basic calcium phosphate, not calcium pyrophosphate dihydrate, underlying the significance of chondrocyte differentiation state and the factors regulating normal and pathological mineralization. Animal models have implicated a general model of crystal-induced inflammation involving innate immunity through the NALP3 (Natch domain, leucine-rich repeat, and PYD-containing protein 3) inflammasome signaling through the interleukin-1 receptor and its signaling protein myeloid differentiation primary response protein 88.

SUMMARY

Genetic analysis has elucidated genes responsible for crystal formation and animal models have unveiled mechanisms in the development of crystal-induced arthritis. Future studies will hasten understanding of the pathology of crystal-induced arthritis and provide new therapies.

Use of height3:waist circumference3 as an index for metabolic risk assessment?

Current anthropometric indices for health risk assessment are indirect measures of total or visceral body fat mass that do not consider the inverse relationship of lean body mass to metabolic risk as well as the non-linear relationship between central obesity and insulin resistance.We examined a new anthropometric index that reflects the relationship of waist circumference (WC) as a risk factor to fat-free mass (FFM) as a protective parameter of body composition. In apopulation of 335 adults (191 females and 144 males; mean age 53 (sd 13·9) years) with ahigh prevalence of obesity (27%) and metabolic syndrome (30%) we derived FFM:WC3 from the best fit of the relationship with metabolic risk factors (plasma triacylglycerol levels and insulin resistance by homeostasis model assessment index). Because FFM is known to be proportional to the cube of height, FFM was subsequently replaced by height3 yielding height3:WC3 as an easily applicable anthropometric index. Significant inverse relationships of height3:WC3 to metabolic risk factorswere observed for both sexes. They slightly exceeded those of conventional anthropometric indicessuch as BMI, WC or WC:hip ratio in women but not in men. The exponential character of the denominator WC3 implies that at a given FFM with gradually increasing WC the increasein metabolic risk is lower than proportional. Further studies are needed to evaluate height3:WC3 as an anthropometric index for health risk assessment.

New developments in the epidemiology and genetics of gout

The prevalence of gout appears to be rapidly increasing worldwide and is no longer a disorder suffered primarily by over-fed alcohol consumers. Emerging risk factors include longevity, metabolic syndrome, and new classes of pharmacologic agents. In some ethnic populations, no obvious risk factors can explain the high incidence of hyperuricemia and gout, suggesting a genetic liability. Studies to identify genes associated with gout have included families with defects in purine metabolism, as well as families in whom the occurrence of gout is secondary to renal disorders such as juvenile hyperuricemic nephropathy and medullary cystic kidney disease. Case-control studies of isolated aboriginal cohorts suffering from primary gout have revealed several chromosomal loci that may harbor genes that are important to the development and/or progression of gout.

EULAR evidence based recommendations for gout. Part I: Diagnosis. Report of a task force of the Standing Committee for International Clinical Studies Including Therapeutics (ESCISIT)

OBJECTIVE

To develop evidence based recommendations for the diagnosis of gout.

METHODS

The multidisciplinary guideline development group comprised 19 rheumatologists and one evidence based medicine expert, representing 13 European countries. Ten key propositions regarding diagnosis were generated using a Delphi consensus approach. Research evidence was searched systematically for each proposition. Wherever possible the sensitivity, specificity, likelihood ratio (LR), and incremental cost-effectiveness ratio were calculated for diagnostic tests. Relative risk and odds ratios were estimated for risk factors and co-morbidities associated with gout. The quality of evidence was categorised according to the evidence hierarchy. The strength of recommendation (SOR) was assessed using the EULAR visual analogue and ordinal scales.

RESULTS

10 key propositions were generated though three Delphi rounds including diagnostic topics in clinical manifestations, urate crystal identification, biochemical tests, radiographs, and risk factors/co-morbidities. Urate crystal identification varies according to symptoms and observer skill but is very likely to be positive in symptomatic gout (LR = 567 (95% confidence interval (CI), 35.5 to 9053)). Classic podagra and presence of tophi have the highest clinical diagnostic value for gout (LR = 30.64 (95% CI, 20.51 to 45.77), and LR = 39.95 (21.06 to 75.79), respectively). Hyperuricaemia is a major risk factor for gout and may be a useful diagnostic marker when defined by the normal range of the local population (LR = 9.74 (7.45 to 12.72)), although some gouty patients may have normal serum uric acid concentrations at the time of investigation. Radiographs have little role in diagnosis, though in late or severe gout radiographic changes of asymmetrical swelling (LR = 4.13 (2.97 to 5.74)) and subcortical cysts without erosion (LR = 6.39 (3.00 to 13.57)) may be useful to differentiate chronic gout from other joint conditions. In addition, risk factors (sex, diuretics, purine-rich foods, alcohol, lead) and co-morbidities (cardiovascular diseases, hypertension, diabetes, obesity, and chronic renal failure) are associated with gout. SOR for each proposition varied according to both the research evidence and expert opinion.

CONCLUSIONS

10 key recommendations for diagnosis of gout were developed using a combination of research based evidence and expert consensus. The evidence for diagnostic tests, risk factors, and co-morbidities was evaluated and the strength of recommendation was provided.

Hyperuricemia and Associated Diseases

After introduction of urate-lowering therapy, asympotomatic hyperuricemia was treated with allopurinol or uricosuric agents in the belief that hyperuricemia and/or gout caused chronic kidney disease. Epidemiologic studies in the 1970s, however, failed to confirm the view that hyperuricemia and gout were independent risk factors for chronic kidney disease. As a result, urate-lowering pharmacotherapy is generally not recommended at the present time in the management of asymptomatic hyperuricemia even though recent epidemiological, experimental, and clinical studies have prompted reexamination of a causal role for hyperuricemia (with or without gout) in chronic kidney disease as well as other important disorders including cardiovascular disease, hypertension, and metabolic syndrome. The issue of such a role remains unresolved and this article reviews the current status of the relationship between hyperuricemia and associated disorders.

Gout is on the increase in New Zealand

OBJECTIVE

To determine the current prevalence of hyperuricaemia and gout in New Zealand Maori and Europeans for comparison with previous studies.

METHODS

342 Maori and 315 European men and women aged 15 years and older were studied by personal interview and a musculoskeletal system examination. The 1977 ARA criteria for gout in a survey setting were used and serum uric acid was determined by a uricase method. The data were compared with those of previous New Zealand studies.

RESULTS

Gout was significantly more common in Maori (6.4%) than Europeans (2.9%) (delta = 3.6%, 95% confidence interval 0.4 to 6.8) and in Maori men (13.9%) than in European men (5.8%) (delta = 8.1%, 95% CI 1.0 to 15.2). Hyperuricaemia was significantly more common in Maori men (27.1%) than in European men (9.4%) (delta = 17.7%, 95% CI 8.3 to 27.1) and in Maori women (26.6%) than in European women (10.5%) (delta = 16.1%, 95% CI 8.5 to 23.7). At least 14% of hyperuricaemic individuals were receiving diuretics, of whom 78% were women. Comparison with previous studies shows that the prevalence of gout has increased in both Maori and Europeans, particularly in men. In Maori men the prevalence of gout has risen from 4.5-10.4% previously to 13.9%, and in European men from 0.7%-2.0% previously to 5.8%. Clinical differences included a stronger family history, earlier age at onset, and a higher frequency of tophi and polyarticular gout in Maori than Europeans. Of those with gout, 62% of Maori and 63% of Europeans were hyperuricaemic on the day surveyed and six (19.4%) were on diuretics. Treatment of gout was inadequate in most cases.

CONCLUSIONS

Hyperuricaemia and gout remain common among Maori. Of concern is that the prevalence of gout appears to be on the increase, not only in Maori but also in Europeans in New Zealand.

Migration and gout: the Tokelau Island migrant study

The prevalence and 14 year incidence of clinical gout and its precursors were investigated in the Polynesian population of Tokelauans living in the Pacific basin, non-migrant Tokelauans living in their isolated atoll homeland being compared with migrant Tokelauans living in urban New Zealand. The age standardised prevalence of gout in Tokelauan men in New Zealand was higher than that in non-migrant Tokelauan men, being 21.0 and 19.5/1000 subjects at the beginning of the study and 51.0 and 14.6/1000 at the end of study, respectively. Migrant men in New Zealand aged under 55 had higher mean serum uric acid concentrations than non-migrant men of the same age. The prevalence of gout was low in women in both environments. The age standardised relative risk of developing gout between 1968 and 1982 was 9.0 times higher in the migrant men than in the non-migrant men. Age, serum uric acid concentration, serum cholesterol concentration, and self reported alcohol consumption at entry to the study were the best set of predictors of gout in men. Preventive strategies to change body mass, diet, and patterns of alcohol use need to be developed in this population.

Hyperuricemia and gout

Gout is a clinical syndrome encompassing a group of metabolic diseases that are all characterized by abnormal uric acid metabolism. In its fullest form, gout is defined by: an increase in the serum urate concentration; characteristic, recurrent, acute arthritic attacks, with monosodium urate monohydrate crystals demonstrable in synovial fluid leukocytes; tophi, usually in and around joints of the extremities, composed of monosodium urate monohydrate deposits; renal disease, often accompanied by hypertension with glomerular, tubular, interstitial, and vascular involvement; and uric acid nephrolithiasis. Any combination of these manifestations may occur, although tophi and urate nephropathy rarely antedate gouty arthritis.

The relationship between Achilles tendon rupture and serum uric acid level

The serum uric acid level of 30 patients with a rupture of the Achilles tendon was compared with that of 30 healthy control subjects matched for age and sex. In patients with a ruptured Achilles tendon the serum uric acid level was significantly higher than in the control subjects. This finding was not dependent on sex or race. It is possible that hyperuricaemia is a contributing factor in rupture of the Achilles tendon and warrants further study. It is suggested that this finding might be related to an adverse effect on the tendon's nutrition.