Serum uric acid in 23,923 men and gout in a subsample of 4257 men in France

Global research trends in hyperuricemia: A bibliometric and visualised study

OBJECTIVES

The global trend of research on hyperuricaemia (HUA) has not been well studied. Therefore, this study aimed to investigate the trend of research on HUA and compare the findings in publications from different countries, institutions, journals, and authors, to predict the research hotspots.

METHODS

Publications related to HUA were searched using the Science Citation Index-Expanded Web of Science. The data were analysed by using the bibliometric methodology. Additionally, a graphical mapping was generated by using the VOS viewer software to carry out a co-occurrence analysis and to investigate the trend of publications in this field.

RESULTS

A total of 6313 articles were included. The number of publications was increasing globally yearly. USA was the leading country in global research in this field, with the largest number of publications and citations as well as the highest H-index (H-index reflects both the number of publications and the number of citations per publication). PLOS One published the largest number of publications related to HUA. JOHNSON RJ T has published the largest number of papers in this field. Published studies could be classified into six clusters: 'Pathophysiology', 'HUA and metabolic syndrome', 'HUA and cardiovascular disease', 'HUA and gout', 'HUA and nephropathy', and 'Genome-wide research'. 'Pathophysiology', 'HUA and cardiovascular disease', 'HUA and gout', and 'Genome-wide research' were predicted as the next hot topics in HUA research.

CONCLUSIONS

USA was the leading country in global research in this field. It is expected that an increasing research output will continue to be observed in the near future. 'Pathophysiology', 'HUA and cardiovascular disease', 'HUA and gout', and 'Genome-wide research' may be the next hotspots and hence need more attention in the future.

Management of hyperuricemia through dietary polyphenols as a natural medicament: A comprehensive review

Hyperuricemia, a condition due to high serum uric acid level and is notorious to health. It is considered to be a potent risk factor for gout and dramatically associated in the development of many chronic diseases such as malignant tumor, cardiovascular disorders and renal failure. Modern innovative medicinal and therapeutic interventions are underlying these days to combat hyperuricemia. Previously reported studies revealed the significant impact of dietary polyphenols (e.g. anthocyanins, phenolic acids, flavonoids etc.) against hyperurecemia disorder. Dietary plant polyphenols, unlike anti- hyperuricemic agents, are not reported to have any side effects in curing hyperuricemia. The current comprehensive review figure outs the use of dietary polyphenols as a natural remedy for the management of hyperuricemia. The sources, affiliated pathways, mode of actions and factors affecting their efficiency to prevent hyperuricemia are deeply discussed in this article. Additionally, limitations and suggestions regarding previously reported studies are also highlighted.

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.

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.

Hyperuricemia as a risk factor for cardiovascular mortality

The value of hyperuricemia as a risk factor for cardiovascular mortality was investigated in 3195 men and 3160 women aged 40-69 years in Finland. Hyperuricemia was associated with obesity, impaired glucose tolerance, hypertension and history of heart disease. The total mortality of hyperuricemic men and women in 5 years was significantly higher than the mortality of normouricemics. Cardiovascular mortality was not higher in hyperuricemics than in normouricemics. However, in hyperuricemic women without known heart disease cardiovascular mortality was significantly increased in the follow-up period between 5 and 12 years. Total and cardiovascular mortality rates were significantly higher in hyperuricemic men with known heart disease than in corresponding normouricemic men. A rise of serum uric acid may be secondary to more advanced atherosclerosis. Thus, hyperuricemia may be associated with more advanced heart disease and it is not an independent cause of cardiovascular diseases.

Implications of disorders of purine metabolism for the kidney and the urinary tract

The spectrum of kidney and urinary tract disorders related to purines comprises acute hyperuricosuric nephropathy, chronic urate nephropathy and urolithiasis. Two factors in the development of acute hyperuricosuric nephropathy are increased uric acid concentration and low pH in the tubular fluid. Chronic urate nephropathy still possess several problems: incidence (although this seems to be decreasing, presumably owing to effective prevention), the source of interstitial urate, the cause of the interstitial deposition of urate, and the role of urate deposits in the pathogenesis of the interstitial nephropathy. The relation of the experimental nephropathy to the pathogenesis of chronic urate nephropathy in the human is not yet clear but a model is proposed according to which interstitial urate derives from two sources: hyperuricaemic plasma and hyperuricosuric tubular fluid. Urolithiasis related to purines leads to uric acid-urate stones, xanthine stones, 2,8-dihydroxyadenine stones, iatrogenic xanthine and oxipurinol stones, and possibly calcium stones. Pathogenetic factors in uric acid lithiasis are hyperuricosuria (whether due to an inborn enzyme abnormality or of unknown aetiology) and low urinary pH; oliguria is a contributory factor. There remain several open questions about uric acid lithiasis: incidence, the shift of its location from lower to upper urinary tract, the interplay of pathogenetic factors, and the role of compounds which inhibit crystallization.

Hyperuricemia and cardiovascular risk factor clustering in a screened cohort in Okinawa, Japan

The relation between serum uric acid level and cardiovascular risk factors is complex and has been investigated mainly in men. We examined the correlation between serum uric acid level and obesity, hypertension, dyslipidemia, and diabetes mellitus (DM) in both men and women of a screened cohort in Okinawa, Japan. A total of 9,914 individuals (6,163 men and 3,751 women ranging in age from 18 to 89 years) who were screened at Okinawa General Health Maintenance Association were subjects in this study. Hyperuricemia was defined as a serum uric acid level > or = 7.0 mg/dl in men and > or = 6.0 mg/dl in women. The odds ratios (95% confidence intervals) for the presence of hyperuricemia in men were 1.75 (1.56-1.97) for obesity, 1.42 (1.25-1.62) for hypertension, 1.16 (1.02-1.30) for hypercholesterolemia, 1.80 (1.60-2.03) for hypertriglyceridemia, 1.19 (1.02-1.40) for hypo-high density lipoprotein (HDL) cholesterolemia, and 0.61 (0.49-0.75) for DM; in women, they were 2.02 (1.62-2.53) for obesity, 1.64 (1.29-2.10) for hypertension, 1.31 (1.04-1.65) for hypercholesterolemia, 1.95 (1.51-2.51) for hypertriglyceridemia, 1.53 (0.96-2.44) for hypo-HDL cholesterolemia, and 1.20 (0.76-1.90) for DM. Hyperuricemic subjects had higher rates of coexistence of two or more of these cardiovascular risk factors than non-hyperuricemic subjects (63.8% vs. 43.2% in men; 58.9% vs. 27.6% in women). The present study revealed that hyperuricemia is positively associated with obesity, hypertension, and dyslipidemia in both men and women, and that hyperuricemic subjects tend to have a clustering of these cardiovascular risk factors.

Serum uric acid and related factors in 500 hospitalized subjects

The study purpose was to determine the following in a large sample of hospitalized patients: (1) the prevalence of hyperuricemia, (2) the association of hyperuricemia with other metabolic disorders, and (3) the factors independently predicting hyperuricemia. Five hundred adult patients (250 men and 250 women) were randomly selected from those admitted as inpatients over a period of 5 months. In all patients, body mass index (BMI), blood pressure, and serum glucose, lipid, creatinine, urea nitrogen, and urate concentrations were measured. The presence of diseases or use of medications known to affect serum urate levels were recorded. The mean level of serum urate was 5.6 mg/dL in the whole sample, 6.0 mg/dL in men and 5.3 mg/dL in women (P = .003, men v women). The prevalence of hyperuricemia was 27.6% (28.8% and 26.4% in men v women, P = nonsignificant). A definite or probable secondary hyperuricemia was found in 87.7% of the subjects. Hyperuricemia was rarely isolated (21%), whereas it was frequently associated with hypertension (60.1%), hyperlipidemia (31.2%), diabetes (28.3%), and obesity (21.7%). In 26.8% of the subjects, hyperuricemia was associated with two metabolic disorders, in 13.8% with three, and in 2.9% with four. Multiple metabolic disorders (three to four) were found in 16.7% of subjects with hyperuricemia. Serum urate levels progressively increased across a range of subjects from those without diabetes, hyperlipidemia, hypertension, or obesity to those with one, two, or a greater number of associated metabolic abnormalities. Multiple stepwise regression analysis showed that 43% of serum urate variability was explained by urea nitrogen levels, triglyceride levels, diuretic therapy, the inverse of creatinine (as an index linearly related to creatinine clearance), and BMI. These results indicate that in hospitalized subjects, hyperuricemia is (1) frequent, (2) a secondary phenomenon in most cases, and (3) frequently associated with other metabolic disorders. The major predictors of high serum urate levels are BMI, triglycerides, parameters of renal function, and use of diuretics. These variables explain a large proportion of serum urate variability.

Uric acid levels in southern Germany in 1989. A comparison with studies from 1962, 1971, and 1984

Since 1962 our group has performed four studies on uric acid values in blood donors in southern Germany (Bavaria). Uric acid levels in men have increased over the years, from 4.86 mg/dl in 1962 to 6.00 mg/dl in 1971, 5.60 mg/dl in 1984, and 5.90 mg/dl in 1989. Levels in women have increased slightly, from 4.05 mg/dl in 1962 to 4.35 mg/dl in 1971, 4.10 mg/dl in 1984, and 4.16 mg/dl in 1989. Women aged 51 to 60 years had significantly higher uric acid levels than those in the fourth decade. In women treated with oral contraceptives uric acid levels were significantly lower than in other women of the same age. Hypouricemia (uric acid levels less than or equal to 2.0 mg/dl) was observed in three women, none of whom had a history of medication. Hyperuricemia exists when uric acid levels are greater than or equal to 6.5 mg/dl. In 1989 2.6% of the female blood donors and 28.6% of the males were hyperuricemic, with an increased risk of gout, nephrolithiasis, and nephropathy.

Heterogeneity in the familial aggregation of fasting serum uric acid level in five North American populations: the Lipid Research Clinics Family Study

This study represents the first formal examination for heterogeneity in the familial aggregation of fasting serum uric acid (UA) levels. Data from 5 clinics (Cincinnati, Stanford, Iowa, Minnesota, and Oklahoma) participating in the Lipid Research Clinics (LRC) family study, which included a total of 685 nuclear families (N = 2,146), were analyzed. Heterogeneity among the clinics in familial resemblance was detected. However, this heterogeneity could not be attributed to differences in distributional properties (such as means and variances) or to path model parameters representing latent genetic or cultural (environmental) components associated with UA levels. Intergenerational differences in genetic heritabilities were found, with higher offspring (h2 = 43%) than parent (h2z2 = 16%) estimates, but no generational differences were detected for cultural heritability (c2 = 0.09). Equal maternal and paternal cultural transmission was found, and effects due to extra sibling environments and to marital resemblance were both significant. These results show no clear indication as to the source of the heterogeneity observed for familial resemblance of UA levels in randomly selected data. This question should be further investigated, especially in clinical samples such as dyslipoproteinemic families.

Serum uric acid, serum glucose and diabetes: relationships in a population study

The relationships between serum uric acid, serum glucose and diabetes have been examined in a survey of 7735 middle-aged men drawn at random from general practices in 24 British towns. There was a positive relationship between serum glucose and serum uric acid concentrations up to about 8.0 mmol/l; at higher levels of glucose, serum uric acid decreased. Uric acid levels were significantly reduced in insulin-dependent diabetics and in those on oral hypoglycaemics and also in 'non-diabetics' with casual glucose levels greater than 10 mmol/l. Both uric acid and glucose concentrations were positively related to body mass index; only uric acid was positively related to alcohol intake. Men on antihypertensive treatment had raised levels of uric acid (significant) and glucose (non-significant). The positive relationship between serum uric acid and serum glucose could not be explained by associations with body mass index, alcohol intake, age, social class, gout or treatment for hypertension. It probably reflects the biochemical interaction between serum glucose and purine metabolism, with increased excretion of uric acid during hyperglycaemia and glycosuria.

Familial hyper- and hypouricemias in random and hyperlipidemic recall cohorts: the Princeton School District Family Study

Using the Princeton School Family Study, our specific aim was to estimate the prevalence of familial hyper- and hypouricemia, to estimate the proportion of probands' first-degree relatives who were similarly affected, and to evaluate the contribution of diseases, drugs, and alcohol intake (if any) to uric acid levels. We studied 379 probands and a total of 1928 subjects, 125 and 52 black probands from a randomly recalled group, 147 white and 55 black probands from a hyperlipidemic recall (top decile cholesterol and/or triglyceride) group. Familial hyper- and hypouricemias were arbitrarily identified in those kindreds having at least two first-degree relatives in the same decile as the proband, top or bottom respectively, for serum uric acid. No probands had symptomatic gout. Diseases, drugs, and alcohol intake were not consistently associated with aggregations of high and/or low uric acid levels in families, and had little relationship to uric acid levels in individuals. Of the 177 randomly recalled probands, and of the 55 black probands in hyperlipidemic recall familial hyperuricemia, with concurrent primary hyperlipoproteinemia and hypertension. Familial hypouricemia was present in 1 of 125 white and in 1 of 52 randomly recalled black kindreds, and in 3 of 147 white and 3 of 55 hyperlipidemic recall black kindreds. While familial clustering of hyperuricemia was limited, clustering of hypouricemia was much more marked. Seventy-four and 84% respectively of first-degree relatives of hypouricemic white and black probands had uric acid less than the 50th percentile. In randomly recalled probands and their first-degree relatives there were significant inverse partial correlations between uric acid and high density lipoprotein cholesterol. Inverse associations of uric acid with high density lipoprotein cholesterol and the concurrence of hyperlipoproteinemia and hypertension in hyperuricemic families points to the importance of lipoprotein and blood pressure screening in families with asymptomatic hyperuricemia. The potential ramifications of within-family clustering of hypouricemia need to be further assessed in populations, particularly in regards to uric acid nephrolithiasis.

Psychosomatic aspects of gout

Hyperuricemia is the specific biochemical vulnerability of gout sufferers. However, hyperuricemia is much more frequent than gout. Gout also is more frequent in men; after menopause gout attacks become more frequent in women; psychosocial factors, like stressful life events, tension, and anxiety can trigger attacks of gout, which modern pharmacology can moderate and control.

Epidemiology of hyperuricemia in an ambulatory elderly population

The relationship of serum uric acid concentration to age and sex was assessed in 1,701 participants in a geriatric multiphasic screening clinic. Included were 1,067 women and 634 men. The mean uric acid level for men was 6.35 mg/100 ml compared to 5.44 mg/100 ml for women. No statistically significant increases in serum uric acid between age groups were apparent, except for women over 84 years of age. The mean serum urate concentrations found in this geriatric study are higher than those reported for other population groups, suggesting a higher normal value for the elderly.

The relationship between uric acid and potassium in normal subjects

The serum uric acid concentration in normal healthy subjects has been studied in relation to sex, height, weight, lean body mass measured from total body potassium and predicted from the Hume-Weyers formula (1971), total body potassium, plasma potassium and urea, and packed cell volume. The strongest correlation was found with sex, but height, weight, total body potassium, lean body mass (measured and predicted) also correlated significantly with serum uric acid concentration. However, when the sex variable was removed, the other factors lost their significant correlation. Finally, total red blood cell and plasma volumes were predicted (Hume and Goldberg, 1964) and from these an estimate of total plasma uric acid, total plasma potassium, and total red blood cell potassium obtained. Measured total body potassium was found to correlate well with total plasma potassium and total red blood cell potassium independent of sex. Total plasma uric acid correlated well with measured total body potassium when both sexes were considered and when separated into male and female groups the males retained a significant correlation as did the female group.

Serum uric acid in England and Scotland

Serum uric acid (SUA) was measured in 512 men and 254 women from two English regions and in 337 men from one Scottish region. Mean SUA levels were the same in the men (5-5 mg/100 ml) and similar in the women (3-9 and 4-1 mg/100 ml). The apparent rarity of gout in Scotsmen cannot be explained by regional differences in SUA levels or in the prevalence of hyperuricaemia (defined as SUA of 7-0 mg/100 ml or over) which was present in 6-6% of the English men and 8% of the Scots. SUA was positively correlated with weight and serum urea, and with age in women, but no variation was found with social class. Body weight was the most important predictor of SUA in both men and women and superior to measurements involving correction for height, such as ponderal index and calculated lean body mass.

Serum uric acid levels in England and Scotland

A survey of serum uric acid levels in 766 subjects in England and 337 in Glasgow was carried out. There was no difference in the frequency distribution of uric acid or the mean levels in the two countries. A serum uric acid of 7 mg/100 ml or over was found in 7.2% of the men and 0.4% of the women. The previously described sex difference and association of serum uric acid with weight were confirmed. No association was found with social class. The suggestion of an increase in uric acid levels in the United Kingdom over the past 14 years is discussed.

Diabetes, prediabetes and uricaemia

Three diabetes surveys carried out at two yearly intervals on 10000 men aged 40 years and over have enabled us to compare four groups of subjects with regard to their serum uric acid level in relation to carbohydrate metabolism. Prediabetics, that is, persons who screened negative at previous surveys and subsequently developed diabetes, had a higher mean uric acid level than normals (p less than 0.001). Their uric acid level was considerably higher than in diabetics, who had a mean value lower than normals (up to p less than 0.001). Men, without diabetes, but having an abnormal GTT were found to have a mean value higher than the normals at each survey.