Hyperuricaemia, gout, and diabetic abnormality in Polynesian people

Hyperuricaemia and gout in the Pacific

Gout is the most common form of inflammatory arthritis in adults worldwide. There has been a steady increase in prevalence, which varies across different geographic areas and is high in the Indigenous (First Nations) peoples of the Pacific region. Palaeo-archaeological studies demonstrate that gout was present in the Pacific region prior to European colonization, which is suggestive of genetic predisposition. Genetic risk factors, including population-specific genetic variants and genetic variants shared across populations, particularly those influencing urate transporters, have been identified in Indigenous peoples of the Pacific that partly explain the earlier age of onset of gout. Indigenous peoples of the Pacific experience severe gout, with frequent flares, high hospitalization rates and tophaceous gout, all aggravated by socio-cultural factors. Despite a specific need for effective gout management, Indigenous peoples of the Pacific are under-represented in gout research and inequities in care continue. Indigenous peoples-led, holistic gout management programmes are systematically and urgently required in this region, where gout is a major public health issue. Importantly, a foundation of cultural safety is necessary to underpin such programmes.

Relationship Between Altered Plasma-Free Amino Acid Levels and Hyperuricemia in Dyslipidemia Without and With Hypertension

Background: Investigating the association between plasma-free amino acids (PFAAs) and hyperuricemia (HU) in dyslipidemia (DL) and dyslipidemia with hypertension (DH) is crucial, as it could provide valuable insights into the pathophysiology of these conditions and contribute to the development of targeted prevention and management strategies. Therefore, in this study, we aimed to elucidate the associations between PFAAs and HU in individuals with DL and DH. Methods: We quantified PFAAs and uric acid levels among Japanese healthy subjects (n = 1311; HU, n = 57), subjects with DL (n = 1483; HU, n = 219), and subjects with DH (n = 1159; HU, n = 237). Results: The concentrations of most PFAAs showed significant differences between subjects without and with HU across all groups (p < 0.05 to 0.001). Adjusted logistic regression analyses revealed that certain PFAAs were consistently positively or negatively associated with HU across all groups. Specifically, in the DL group, alanine, tryptophan, and tyrosine showed significant positive associations with HU, while in the DH group, citrulline and glutamate exhibited similar positive associations (p < 0.05 to 0.001). Conversely, threonine in the healthy group (p < 0.05) and glutamine in the DL group (p < 0.05) demonstrated significant inverse associations with HU. Conclusions: This study revealed a potential close relationship between alterations in PFAA profiles and HU in dyslipidemia, without and with hypertension. The findings warrant further research to elucidate the role of altered amino acid and uric acid levels as potential disease biomarkers and therapeutic targets.

Gout in Native Hawaiian Patients in Hawai'i: Clinical Characteristics and Disparities

OBJECTIVE

The purpose of this study was to investigate differences in clinical characteristics and health care use of Native Hawaiian and White patients with gout.

METHODS

We performed a retrospective chart review of Native Hawaiian and White patients with gout treated from 2011 to 2017 within a large health care system in Hawai'i. We compared demographic characteristics, clinical outcomes, and risk factors for gout. We used multivariable logistic regression to identify predictive factors of emergency department visits.

RESULTS

We identified 270 Native Hawaiian patients with gout and 239 White patients with gout. The Native Hawaiian patients were younger on average (54.0 vs 64.0 years; P < 0.0001) and had an earlier onset of disease (50.0 vs 57.0 years; P < 0.0001). Native Hawaiian patients with gout had higher mean (7.58 vs 6.87 mg/dL; P < 0.0001) and maximum (10.30 vs 9.50 mg/dL; P < 0.0001) serum urate levels compared to White patients with gout. Native Hawaiian patients with gout also had a greater number of tophi (median 2.00 vs 1.00; P < 0.0001). Native Hawaiians patients with gout were 2.7 times more likely to have frequent (≥1) emergency department visits than White patients with gout. Native Hawaiian patients with gout were less likely to have a therapeutic serum urate ≤6.0 mg/dL and had lower rates of rheumatology specialty care.

CONCLUSION

Native Hawaiian patients have a higher disease burden of gout, with earlier disease onset and more tophi. Native Hawaiian patients with gout are more likely to use emergency services for gout and have lower rates of rheumatology specialty care compared to White patients. Future studies are needed to promote culturally appropriate preventive care and management of gout in Native Hawaiians.

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.

Systematic review of rheumatic disease epidemiology in the indigenous populations of Canada, the United States, Australia, and New Zealand

OBJECTIVE

Past publications have highlighted an excess rheumatic disease incidence and prevalence in indigenous populations of Canada (First Nations, Inuit, and Métis), and the United States of America (Alaska Native and American Indian). We have updated these reviews and expanded the scope to include New Zealand (Maori) and Australia (Aborigine) indigenous populations.

METHODS

We performed a broad search using medical literature databases, indigenous specific online indexes, and government websites to identify publications reporting the incidence and/or prevalence of arthritis conditions (rheumatoid arthritis, spondyloarthropathies, gout, osteoarthritis, systemic autoimmune rheumatic diseases, and juvenile idiopathic arthritis) in the indigenous populations of Canada, America, New Zealand, and Australia. A narrative synthesis by type of arthritis was prepared given the heterogeneity of study designs used in the primary studies.

RESULTS

Of 5269 titles and abstracts, 88 met inclusion criteria. Osteoarthritis was found to affect up to 17% of American Indian/Alaska Native women, 22% of Canadian First Nations, 32% of Australian Aborigine, and 6% of New Zealand Maori populations. The prevalence of rheumatoid arthritis, systemic lupus erythematosus, and juvenile idiopathic arthritis was consistently significantly higher in indigenous populations. Several studies describing the prevalence of spondyloarthropathy in North American northern populations were identified, but with no comparison populations the relative frequency could not be commented on. Gout was more prevalent in Maori compared to general population New Zealanders.

CONCLUSIONS

This comprehensive summary describes rheumatic disease burden in indigenous populations in four countries with similar disparities in social determinants of health, to inform clinical service requirements to meet population need.

Lowering Uric Acid With Allopurinol Improves Insulin Resistance and Systemic Inflammation in Asymptomatic Hyperuricemia

BACKGROUND

Hyperuricemia is an independent predictor of impaired fasting glucose and type 2 diabetes, but whether it has a causal role in insulin resistance remains controversial. Here we tested the hypothesis that lowering uric acid in hyperuricemic nondiabetic subjects might improve insulin resistance.

METHODS

Subjects with asymptomatic hyperuricemia (n = 73) were prospectively placed on allopurinol (n = 40) or control (n = 33) for 3 months. An additional control group consisted of 48 normouricemic subjects. Serum uric acid, fasting glucose, fasting insulin, HOMA-IR (homeostatic model assessment of insulin resistance), and high-sensitivity C-reactive protein were measured at baseline and at 3 months.

RESULTS

Allopurinol-treated subjects showed a reduction in serum uric acid in association with improvement in fasting blood glucose, fasting insulin, and HOMA-IR index, as well as a reduction in serum high-sensitivity C-reactive protein. The number of subjects with impaired fasting glucose significantly decreased in the allopurinol group at 3 months compared with baseline (n = 8 [20%] vs n = 30 [75%], 3 months vs baseline, P < 0.001). In the hyperuricemic control group, only glucose decreased significantly and, in the normouricemic control, no end point changed.

CONCLUSIONS

Allopurinol lowers uric acid and improves insulin resistance and systemic inflammation in asymptomatic hyperuricemia. Larger clinical trials are recommended to determine if lowering uric acid can help prevent type 2 diabetes.

Pacific Populations, Metabolic Disease and 'Just-So Stories': A Critique of the 'Thrifty Genotype' Hypothesis in Oceania

Pacific populations have long been observed to suffer a high burden of metabolic disease, including obesity, type 2 diabetes and gout. The 'Thrifty Genotype' hypothesis has frequently been used to explain this high prevalence of disease. Here, the 'Thrifty Genotype' hypothesis and the evolutionary background of Pacific populations are examined. We question its relevance not only in the Pacific region but more generally. Not only has the hypothesis not been explicitly tested, but most archaeological and anthropological data from the Pacific fundamentally do not support its application.

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.

Population-specific influence of SLC2A9 genotype on the acute hyperuricaemic response to a fructose load

BACKGROUND

SLC2A9 is a strong genetic risk factor for hyperuricaemia and gout. SLC2A9 (GLUT9) is a high capacity urate transporter and reportedly transports glucose and fructose. Intake of fructose-containing beverages is associated with development of hyperuricaemia and gout.

OBJECTIVE

To determine whether genetic variation in SLC2A9 influences the acute serum urate response to a fructose load.

METHODS

Following an overnight fast, 76 healthy volunteers (25 Māori, 26 Pacific, 25 European Caucasian) drank a solution containing 64 g fructose. Serum and urine were obtained immediately before and then 30, 60, 120 and 180 min after ingestion. The SLC2A9 single nucleotide polymorphism (SNP) rs11942223 was genotyped and data were analysed based on the presence or absence of the gout protective minor allele (C).

RESULTS

The rs11942223 C allele was present in 17 participants (22%). In the entire group, fructose intake led to an increase in serum urate, which peaked 60 min following fructose ingestion (analysis of variance p=0.006). The presence of the C allele was associated with an attenuated hyperuricaemic response (p(SNP)<0.0001) and increased fractional excretion of uric acid (FEUA) (p(SNP)<0.0001) following the fructose load. The effects of rs11942223 variants on serum urate and FEUA in response to fructose were present only in Caucasian ancestral subgroups but not in the Māori and Pacific ancestral subgroup.

CONCLUSIONS

Variation in SLC2A9 influences acute serum urate and FEUA responses to a fructose load. SLC2A9 genotype may influence the development of gout on exposure to fructose-containing beverages, particularly in European Caucasian populations.

The experience and impact of gout in Māori and Pacific people: a prospective observational study

Although high prevalence of gout in Māori and Pacific people is well-documented, the experience of disease in these groups has not been explored in detail. The aim of this analysis was to describe the experience and impact of gout in Māori and Pacific people. Patients with gout for <10 years were recruited from primary and secondary care settings into a prospective observational study (n = 291; 37 Māori, 35 Pacific, and 219 not Māori or Pacific). Participants attended a baseline study visit which included a comprehensive clinical assessment. Serum urate, flare frequency and activity limitation were recorded at baseline and after 1 year. Māori and Pacific participants had earlier age of onset (by 9 years), higher flare frequency and more features of joint inflammation. Serum urate concentrations were higher in the Māori and Pacific patients at baseline, despite greater use of allopurinol. Māori and Pacific patients reported greater pain and activity limitation and lower health-related quality of life. The cost of gout treatment was more than three times higher in the Māori and Pacific patients. After 1 year, the higher flare frequency and activity limitation persisted in the Māori and Pacific patients. Māori and Pacific people with gout experience early onset, severe disease with frequent flares and poorly controlled hyperuricaemia. Māori and Pacific ethnicity should be recognised as a prognostic factor for more severe outcomes in this disease, and intensive efforts should be made to work with these patients to control serum urate and prevent flares.

Prescription and dosing of urate-lowering therapy, rather than patient behaviours, are the key modifiable factors associated with targeting serum urate in gout

Background

Long term serum urate (SU) lowering to a target of <0.36 mmol/l (6 mg/dl) is recommended for effective gout management. However, many studies have reported low achievement of SU targets. The aim of this cross-sectional study was to examine the clinical and psychological factors associated with SU targets in patients with gout.

Methods

Patients with gout for <10 years were recruited from primary and secondary care settings. SU target was defined as SU concentration <0.36 mmol/L at the time of the study visit. Both clinical and psychological factors associated with SU target were analysed. The relationship between SU target and measures of gout activity such as flare frequency, tophi, work absences, and Health Assessment Questionnaire-II was also analysed.

Results

Of the 273 patients enrolled into the study, 89 (32.6%) had SU concentration <0.36 mmol/L. Urate-lowering therapy (ULT) use was strongly associated with SU target (p < 0.001). In those patients prescribed ULT (n = 181), allopurinol dose, patient confidence to keep SU under control, female sex, and ethnicity were independently associated with SU target. Other patient psychological measures and health-related behaviours, including adherence scores, were not independently associated with SU target in those taking ULT. Creatinine clearance, diuretic use, age, and body mass index were not associated with SU target. Patients at SU target reported lower gout flare frequency, compared with those not at target (p = 0.03).

Conclusions

ULT prescription and dosing are key modifiable factors associated with achieving SU target. These data support interventions focusing on improved use of ULT to optimise outcomes in patients with gout.

Serum urate in chronic gout--will it be the first validated soluble biomarker in rheumatology?

OBJECTIVE

To summarize evidence for and endorsement of serum urate (SU) as having fulfilled the OMERACT filter as a soluble biomarker in chronic gout at the 2010 Outcome Measures in Rheumatology Meeting (OMERACT 10).

METHODS

Data were presented to support the use of SU as a soluble biomarker in chronic gout and specifically the ability to utilize it to predict future patient-reported outcomes.

RESULTS

SU was accepted as having fulfilled the OMERACT filter by 78% of voters. However, consensus was not obtained regarding its use as a soluble biomarker in chronic gout. Although the majority of the criteria for a soluble biomarker were fulfilled, the key criterion of association of the biomarker with outcomes was not agreed upon. It was agreed that the appropriate choice of endpoint must be linked to its clinical importance to the individual with the disorder and its temporal relationship to the intervention. Appropriate outcomes in chronic gout may therefore include gout flares, reduction in tophi, and patient-reported outcomes.

CONCLUSION

SU is a critical outcome measure. It has the potential to fulfil criteria for a soluble biomarker. Further analyses of existing data from randomized controlled trials will be required to determine whether SU can predict future important outcomes, in particular disability.

High prevalence of gouty arthritis among the Hmong population in Minnesota

OBJECTIVE

The prevalence of gout is on the rise worldwide, especially among newly industrialized populations. We evaluated the prevalence of gout in the recently established Hmong of Minneapolis/St. Paul (MSP) compared with that in non-Hmong populations.

METHODS

The prevalence of self-reported gout in the Hmong population was estimated from 2 cross-sectional community surveys and compared with national data extrapolated from the Third National Health and Nutrition Examination Survey. The prevalence of physician-diagnosed gout in Hmong and non-Hmong MSP residents was separately estimated from the diagnosis codes of 11 MSP primary care clinics.

RESULTS

The prevalence of self-reported gout among MSP Hmong was 2-fold higher than in the general US population (6.5% versus 2.9%; P < 0.001). Although women of both groups reported gout at a rate of 1.9%, Hmong men were significantly more likely than their non-Hmong counterparts to report gout (11.5% versus 4.1%; P < 0.001). Similar results were observed when investigating physician-diagnosed gout in MSP (2.8% Hmong versus 1.5% non-Hmong; P < 0.001). No difference was observed between the women of the 2 groups (0.8% versus 0.7%; P = 0.833), whereas Hmong men were more than twice as likely to be diagnosed with gout compared with their non-Hmong counterparts (6.1% versus 2.5%; P < 0.001). Among Hmong men, advancing age was associated with a considerably higher likelihood of being diagnosed with gout.

CONCLUSION

A significant association is observed between Hmong ethnicity and gout, both self-reported and physician diagnosed. This unique population may provide an opportunity to further our understanding of the pathophysiology of gout.

Hypothesis: could excessive fructose intake and uric acid cause type 2 diabetes?

We propose that excessive fructose intake (>50 g/d) may be one of the underlying etiologies of metabolic syndrome and type 2 diabetes. The primary sources of fructose are sugar (sucrose) and high fructose corn syrup. First, fructose intake correlates closely with the rate of diabetes worldwide. Second, unlike other sugars, the ingestion of excessive fructose induces features of metabolic syndrome in both laboratory animals and humans. Third, fructose appears to mediate the metabolic syndrome in part by raising uric acid, and there are now extensive experimental and clinical data supporting uric acid in the pathogenesis of metabolic syndrome. Fourth, environmental and genetic considerations provide a potential explanation of why certain groups might be more susceptible to developing diabetes. Finally, we discuss the counterarguments associated with the hypothesis and a potential explanation for these findings. If diabetes might result from excessive intake of fructose, then simple public health measures could have a major impact on improving the overall health of our populace.

Hypothesis: fructose-induced hyperuricemia as a causal mechanism for the epidemic of the metabolic syndrome

The increasing incidence of obesity and the metabolic syndrome over the past two decades has coincided with a marked increase in total fructose intake. Fructose--unlike other sugars--causes serum uric acid levels to rise rapidly. We recently reported that uric acid reduces levels of endothelial nitric oxide (NO), a key mediator of insulin action. NO increases blood flow to skeletal muscle and enhances glucose uptake. Animals deficient in endothelial NO develop insulin resistance and other features of the metabolic syndrome. As such, we propose that the epidemic of the metabolic syndrome is due in part to fructose-induced hyperuricemia that reduces endothelial NO levels and induces insulin resistance. Consistent with this hypothesis is the observation that changes in mean uric acid levels correlate with the increasing prevalence of metabolic syndrome in the US and developing countries. In addition, we observed that a serum uric acid level above 5.5 mg/dl independently predicted the development of hyperinsulinemia at both 6 and 12 months in nondiabetic patients with first-time myocardial infarction. Fructose-induced hyperuricemia results in endothelial dysfunction and insulin resistance, and might be a novel causal mechanism of the metabolic syndrome. Studies in humans should be performed to address whether lowering uric acid levels will help to prevent this condition.

Uric acid, evolution and primitive cultures

Hypertension is epidemic and currently affects 25% of the world's population and is a major cause of stroke, congestive heart failure, and end-stage renal disease. Interestingly, there is evidence that the increased frequency of hypertension is a recent event in human history and correlates with dietary changes associated with Westernization. In this article, we review the evidence that links uric acid to the cause and epidemiology of hypertension. Specifically, we review the evidence that the mutation of uricase that occurred in the Miocene that resulted in a higher serum uric acid in humans compared with most other mammals may have occurred as a means to increase blood pressure in early hominoids in response to a low-sodium and low-purine diet. We then review the evidence that the epidemic of hypertension that evolved with Westernization was associated with an increase in the intake of red meat with a marked increase in serum uric acid levels. Indeed, gout and hyperuricemia should be considered a part of the obesity, type 2 diabetes, and hypertension epidemic that is occurring worldwide. Although other mechanisms certainly contribute to the pathogenesis of hypertension, the possibility that serum uric acid level may have a major role is suggested by these studies.

Community-based study in Taiwan aborigines concerning renal dysfunction in gout patients

OBJECTIVE

To reveal the factors associated with renal dysfunction among gout patients in Taiwan aborigines.

METHODS

Social demographic data, alcohol consumption data, anthropometric measurements, blood samples, and 24-h urine samples were collected from 128 aboriginals (101 men, 27 women) suffering from gout.

RESULTS

The men displayed higher mean creatinine clearance (Ccr) values than women. Twenty-two post-menopausal women had significantly lower Ccr values compared to the five pre-menopausal women [probability (p)<0.001]. The males displayed higher 24-h urinary creatinine value than females (8.60+/-5.39 versus 5.58+/-2.14 mmol/L; p<0.05), and showed a significantly higher positive relationship between 24-h urinary creatinine and uric acid excretion [correlation coefficient (r)=0.7304; p<0.001], whereas the females did not (r=0.1144; p=0.5691). Overall, those who were older members of the Tsou tribe, or had excreted less uric acid from urine in 24 h tended to suffer renal dysfunction.

CONCLUSIONS

Gout patients displayed diversity in renal function. An exogenous source of creatinine in men was more likely than in women.

Complex segregation and linkage analysis of familial gout in Taiwanese aborigines

OBJECTIVE

The prevalence of gout and hyperuricemia in Taiwanese aborigines is remarkably high. Although previous studies have failed to find evidence of a major gene responsible for gout, the disease is thought to involve genetic predisposition. We sought to determine whether genetic factors for familial gout exist among Taiwanese aborigines, and, if so, their chromosomal location.

METHODS

We first performed complex segregation analysis. The study sample comprised 945 relatives distributed in 64 pedigrees; among them, 261 affected members (including probands) were found. In all of the aboriginal probands with gout, the disease was diagnosed and confirmed by rheumatologists. Blood specimens were then collected from 127 individuals living in one community that was used in the segregation analysis (from 25 pedigrees, 36 nuclear families, and 112 full sibpairs), and sibpair linkage analysis and a combined transmission disequilibrium test (TDT) method were used to test the genetic components.

RESULTS

In segregation analysis, after adjusting for sex and age, an autosomal-arbitrary major gene model was found to fit the data best, with disease allelic frequency of 0.31 and susceptibility of 0.92. In sibpair analysis, there was a clustering of many flanking markers showing significant linkage, including D1S498 (regression coefficient -0.52), D1S2635 (regression coefficient -0.47), and D1S196 (regression coefficient -0.51), in the 1q21 region of chromosome 1 (all P < 0.005). Results of the combined TDT showed that the marker D1S484 was significantly associated (had linkage) with allele 1 and was transmitted more frequently than other markers to the affected offspring (P < 0.005).

CONCLUSION

Results of this study provide evidence of a genetic basis for familial gout in the aboriginal Taiwanese population and suggest that a susceptibility locus may be located in the 1q21 region of chromosome 1.

A case-control study of the association of diet and obesity with gout in Taiwan

BACKGROUND

Gout has been a significant metabolic disorder for Chinese men in Taiwan; however, there is insufficient information on diet and lifestyle risk factors in this population.

OBJECTIVE

The purpose of this case-control study was to explore potential dietary and lifestyle risk factors associated with gout in Chinese men.

DESIGN

Between 1998 and 1999, we recruited and conducted face-to-face interviews with patients from outpatient clinics in Taipei who had incident gout (n = 92) and with their healthy coworkers (controls; n = 92).

RESULTS

Systolic blood pressure, diastolic blood pressure, waist-to-hip ratio, waist-to-height ratio, and body mass index were significantly higher in cases than in controls. Family histories of gout and diabetes mellitus were strong risk factors for gout. Frequencies of vegetable and fruit consumption were significantly lower in cases than in controls. Logistic regression analyses showed that high alcohol intake and low intakes of fiber, folate, and vitamin C increased the risk of gout, but no association was found with purine intake. After covariates were controlled for, the adjusted odds ratios for the middle and highest tertiles of waist-to-height ratio (0.50-0.54 and >/==" BORDER="0"> 0.55, respectively) were 3.89 (95% CI: 1.32, 11.46) and 4.37 (1.18, 16.22), respectively, but no linear association was found for waist-to-hip ratio and waist circumference.

CONCLUSIONS

Consumption of alcohol, but not of purine, may be a significant dietary risk factor for gout. Food sources rich in dietary fiber, folate, and vitamin C, such as fruit and vegetables, protect against gout. Waist-to-height ratio, which indicates central obesity, has a significant linear effect on gout occurrence, independent of body mass index.

Diabetes in New Zealand

While the ethnic make up of the New Zealand population is predominantly European, the Polynesian population, consisting of indigenous New Zealand Maori and more recent immigrants from the other Pacific Islands is increasing rapidly. The prevalence of diabetes in these Polynesians is high. There is also an increasing prevalence of obesity, and obesity is a greater problem amongst Polynesian people. The number of elderly people in the population is increasing. All of these demographic changes are increasing the incidence and prevalence of Type 2 diabetes. The incidence of Type 1 diabetes is also rising, although the reasons for this are unknown. Diabetic nephropathy is the most common cause of end stage renal failure in New Zealand. Polynesian people with diabetes, and in particular Maori, have a very high rate of diabetic nephropathy and develop renal failure at a more rapid rate than European patients with nephropathy relating to Type 1 diabetes. The propensity for Maori patients with Type 2 diabetes to develop renal failure may relate to a younger age at the onset of diabetes, a genetic susceptibility to nephropathy, and socio-economic or cultural factors leading to less adequate medical care.

Rheumatic disease and the Australian aborigine

OBJECTIVE

To document the frequency and disease phenotype of various rheumatic diseases in the Australian Aborigine.

METHODS

A comprehensive review was performed of the archaeological, ethnohistorical, and contemporary literature relating to rheumatic diseases in these indigenous people.

RESULTS

No evidence was found to suggest that rheumatoid arthritis (RA), ankylosing spondylitis (AS), or gout occurred in Aborigines before or during the early stages of white settlement of Australia. Part of the explanation for the absence of these disorders in this indigenous group may relate to the scarcity of predisposing genetic elements, for example, shared rheumatoid epitope for RA, B27 antigen for AS. In contrast, osteoarthritis appeared to be common particularly involving the temporomandibular joint, right elbow and knees and, most probably, was related to excessive joint loading in their hunter gatherer lifestyle. Since white settlement, high frequency rates for rheumatic fever, systemic lupus erythematosus, and pyogenic arthritis have been observed and there are now scanty reports of the emergence of RA and gout in these original Australians.

CONCLUSION

The occurrence and phenotype of various rheumatic disorders in Australian Aborigines is distinctive but with recent changes in diet, lifestyle, and continuing genetic admixture may be undergoing change. An examination of rheumatic diseases in Australian Aborigines and its changing phenotype may lead to a greater understanding of the aetiopathogenesis of these disorders.

Gout and hyperuricaemia

We have recounted the remarkable story of gout and hyperuricaemia in the indigenous populations of the Pacific and noted the recent identification of the same problem in communities in rural Indonesia. Gout is increasingly recognized in African populations, especially in urban centres. There is no doubt that gout is 'alive and well' and presents a continuing challenge to future generations in developing countries.

Prevalence of ischaemic ECG abnormalities according to the diabetes status in the population of Fiji and their associations with other risk factors

The prevalence of ECG abnormalities indicating the presence of coronary heart disease was examined in the Melanesian (444 men and 457 women) and Asian Indian (408 men and 435 women) population living in Fiji. The aim of the present analysis was to determine the levels of coronary risk factors in people with diabetes, impaired glucose tolerance (IGT) or normal glucose tolerance. The prevalence of ECG abnormalities suggesting coronary heart disease (Q-waves, ST-depression or T-wave changes) was higher among women than men and among Asian Indians than Melanesians. The prevalence of ECG abnormalities was highest in diabetic subjects, intermediate in people with IGT and lowest in people who had normal glucose tolerance. People with IGT were more likely than others to have high risk factor levels. In people with IGT the increased levels of other coronary risk factors might explain a great deal of the increased prevalence of the ECG abnormalities as compared with the prevalence in those with normal glucose tolerance. Also in diabetic subjects, the levels of other coronary risk factors were increased in those who had ECG abnormalities, but not more than was the case with IGT, so that diabetes itself seemed to remain as the major identified risk factor for ECG abnormalities. The prevalence of diabetes in our study populations, especially in Asian Indians, was very high. This suggests that diabetes is the major risk factor for coronary heart disease in such populations.

Diuretics and hyperuricemia in the elderly

Serum uric acid (SUA) was studied in a rural population of 420 males and 592 females aged 65 years or more. The mean SUA concentration was 0.313 mmol/l in males and 0.316 mmol/l in females. In males, 47 (11.2%) and in females 60 (10.1%) had a SUA level of 0.42 mmol/l or more. Both the mean serum values and the frequency of hyperuricemia were higher than 11 years earlier in another, similar study. The SUA concentration was 0.361 mmol/l in the 435 individuals using diuretics and 0.281 mmol/l in the remaining 578. Of the 107 hyperuricemic individuals, 82% used diuretics, and only 2 out of those 20 where the SUA level was 0.50 mmol/l or more did not use diuretics. Apart from diuretics, only the serum creatinine concentration, the Body Mass Index, body weight and the hematocrit level were significantly associated with hyperuricemia in both sexes.

Hypertension and indicators of coronary heart disease in Wallis Polynesians: an urban-rural comparison

A comparative study of hypertension, and indicators of and risk factors for coronary heart disease was undertaken in samples of rural Wallisians of Wallis Island, and first generation Wallisian migrants in the urban centre of Noumea, New Caledonia. Approximately 20% of the adult population of the two communities was included in the study. Higher mean blood pressure and hypertension prevalence in Wallisians in Noumea compared to those in Wallis was documented. There was no significant rise in blood pressure with age in rural Wallisian males. Wallisians in Noumea tended to be more obese than those in Wallis (particularly females). Although differences in the extent of obesity appeared to explain some of the differences in blood pressure between populations of Wallis and Noumea, other environmental factors (such as salt intake) are probably important. There was a trend for a higher prevalence of Q wave changes on the ECG in urbanized Wallisians compared to their rural counterparts. There was no significant or consistent differences in plasma lipid concentrations between the two groups. The prevalence of diabetes was 7 and 4 times higher in Noumea compared to Wallis for males and females respectively. Differences in diabetes and hypertension prevalence are more likely to account for the variation in ischaemic heart disease than plasma lipid levels.

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.

Diabetes in Wallis Polynesians: a comparison of residents of Wallis Island and first generation migrants to Noumea, New Caledonia

A comparative study of diabetes, impaired glucose tolerance and obesity was undertaken in samples of rural Wallisians of Wallis Island and first generation Wallisian migrants in the urban centre of Noumea, New Caledonia. Approximately 20-25% of the adult population of the 2 communities was included in the study. Wallisians in Noumea tended to be more obese than those in Wallis (particularly females). The prevalence of diabetes was 7 and 4 times higher in Noumea compared to Wallis for males and females respectively. Differences in the extent of obesity appeared to account for some of the difference in prevalence of diabetes, but other environmental factors (such as constituents of the diet, and exercise) must be operative as well. The results of this study are consistent with previous findings concerning environmental determinants of diabetes in Pacific populations.

Hyperlipemia and arteriosclerotic cardiovascular disease in the Polynesian population of Rarotonga

Total cholesterol, total triglyceride and high density lipoprotein (HDL) cholesterol and their relation to arteriosclerotic cardiovascular disease (ASCVD) were investigated in a population of Polynesian Maoris in Rarotonga who are becoming increasingly westernized. 8.5% of the population had plasma triglyceride elevations (triglyceride greater than or equal to 200 mg/dl), and the occurrence of hypertriglyceridemia was significantly higher in males than females. 5.8% of the population had elevations of total cholesterol (cholesterol greater than or equal to 250 mg/dl), and the proportion with elevation of total cholesterol was similar for males and females. 3.2% of the population had elevations of both triglyceride and cholesterol. HDL cholesterol concentrations were relatively low, and no sex differences were observed at any age. Analysis of lipoprotein cholesterol and triglyceride in a subset of those who had hyperlipemia indicated that the elevations of total cholesterol and triglyceride were mainly due to elevations of low density lipoprotein (LDL) cholesterol and very low density lipoprotein (VLDL) triglyceride, respectively; furthermore, elevations of VLDL triglyceride and LDL cholesterol were significantly correlated with increase in VLDL apolipoprotein B (apo B) and LDL apo B, respectively. Although an appreciable prevalence of diabetes was observed in this population (male: 6.7%, female: 8.4%), the diabetes could not account for the hyperlipemia. Among 693 subjects between the ages of 30 and 59 years, approx. 3% of males and 1% of females had Q-wave changes, and 16% of females and 4% of males had ST-T changes. Among males with Q-wave abnormalities, hyperlipemia was more frequent. There was also increased frequency of hypertension in those with elevated lipids. The data indicate the occurrence of some hyperlipemia in this population which could be of the familial-combined type; the elevated plasma lipids may contribute to the increased frequency of coronary heart disease.

Physical activity and prevalence of diabetes in Melanesian and Indian men in Fiji

In Fiji Melanesian and Indian men, prevalence of diabetes is more than twice as high in those graded as sedentary or undertaking light activity as in those classed as performing moderate or heavy exercise. This difference was present in both ethnic groups, and maintained when age, obesity, and urban/rural- status were taken into account. It is concluded that, in the population under study, there is epidemiological evidence for the role of physical inactivity as an independent risk factor for Type 2 (non-insulin-dependent) diabetes.

Gout in South African blacks

A retrospective study was carried out to determine the frequency, age of onset, mode of presentation, pattern of joint involvement, and incidence of primary and secondary gout in black patients with gout who were admitted to the King Edward VIII Hospital in Durban, South Africa. Nineteen patients were admitted to hospital with gout over a 5-year period from 1977 to 1981. The admission rate was found to be 4.7/100 000 hospital admissions. Five patients (26%) presented with monoarthritis and 14 patients (74%) had polyarthritis on admission. The joints most frequently involved were the knees (74%), the first metatarsophalangeal (MTP) joint (58%), and ankles (42%). The serum uric acid (SUA) was increased in 94%, and tophi were noted clinically in 47%. Eight patients (42%) with hypertension were on treatment with diuretics and 7 of these patients had a raised blood urea. These 8 patients (42%) were considered to have secondary gout, while no secondary causes were noted in the remaining 11 patients (58%) who had primary gout.

Elevated erythrocyte phosphoribosylpyrophosphate and ATP concentrations in Japanese sumo wrestlers

1. Japanese sumo wrestlers have a diet rich in energy, which results in marked obesity. Their plasma urate and triglyceride levels were significantly elevated. 2. Erythrocyte phosphoribosylpyrophosphate (PRPP) and ATP concentrations in sumo wrestlers were significantly elevated when compared to the levels in control subjects. 3. There were no significant differences in erythrocyte PRPP synthetase (EC 2.7.6.1), purine nucleoside phosphorylase (EC 2.4.2.1) and hypoxanthine guanine phosphoribosyl transferase (EC 2.4.2.8) activities between sumo wrestlers and control subjects. 4. Erythrocyte adenosine kinase (EC 2.7.1.20), adenosine deaminase (EC 3.5.4.4) and adenine phosphoribosyl transferase (EC 2.4.2.7) activities in sumo wrestlers were significantly elevated. 5. It seems that sumo wrestlers have an increased turnover of adenine nucleotides which may contribute to hyperuricaemia.

Glucose tolerance in two unacculturated Indian tribes of Brazil

Plasma levels of glucose, insulin, growth hormone, and pancreatic polypeptide in response to a standard oral glucose load were studied in the Yanomama and the Marubo, two relatively unacculturated Amerindian tribes of the Brazilian Amazon. The findings in the two tribes differed significantly from each other and in the degree of deviation from control subjects. The average responses in both tribes differed significantly from those of age- and sex-matched Caucasoid control subjects studied in Ann Arbor, Michigan; however, of the two tribes, the Marubo, the more acculturated group, resembled the controls more closely. Plasma concentrations of glucose and the hormones at three time points (fasting, 1 h, 2 h) were compared by means of a multivariate analysis. When the Marubo were compared with the control subjects, the only highly significant difference was in the plasma glucose concentrations (all three points were higher in the Marubo); however, the Yanomama differed significantly from the control subjects with respect to all four plasma indicators (p less than 0.05). Unlike the Marubo, the Yanomama showed no significant rise in plasma glucose at 1 h and no decrease at 2 h. Neither tribe exhibited the bimodality of the 2 h glucose value characteristic of acculturated Amerindians, such as the Pima, but the samples studied were small.

Ischaemic heart disease in New Zealand Maori and non-Maori: an age adjusted incidence in hospitalised patients over 10 years with emphasis on clinical features in the Maori

The average annual incidence in a patients admitted to hospital with ischaemic heart disease is lower among Maori than non-Maori but Maori females under 55 years are particularly susceptible. The age adjusted incidence in this group is twice that of white females. One-third of Maori patients had auricular fibrillation and large hearts and it is suggested that these patients have cardiomyopathy, probably alcohol induced, in addition to ischaemic heart disease. This group had the highest hospital mortality rate, 43%. The 30% hospital mortality rate among all Maori is three times that of non-Maori. Risk factors examined in the Maori included obesity (present in 65%), diabetes (in 30%), gout (in 23%) and hypertension (in 17%) of patients with ischaemic heart disease.