Epidemiology of serum uric acid and gout in Frenchmen

An association of smoking with serum urate and gout: A health paradox

BACKGROUND

The potential effect of cigarette smoking on levels of serum urate and risk of gout has been considered by a large number of studies, either as the primary variable of interest or as a covariate.

METHODS

Here we systematically review the published evidence relating to the relationship of smoking with serum urate, hyperuricaemia, and gout.

RESULTS

Many studies have reported that smoking reduces serum urate, however, the evidence has not been conclusive with other studies pointing to the opposite or no effect. It has also been suggested that smoking reduces the risk of gout, although there is some evidence to contradict this finding.

CONCLUSION

A consensus has yet to be reached as to the effect of smoking on serum urate levels and the risk of gout.

Gouty arthropathy: Review of clinico-pathologic and imaging features

Gout is a common inflammatory arthropathy in adults, with the prevalence increasing in males of older age. It occurs when monosodium urate (MSU) crystals are deposited in joints and connective tissue causing inflammation. The gold standard for the diagnosis of gout is the demonstration of negatively birefringent, needle-shaped MSU crystals through synovial fluid aspiration. However, this is an invasive technique and may not always be conclusive or feasible. Imaging techniques have been developed to aid in diagnosis of gout non-invasively. Radiography has a low utility in the early diagnosis of gout and demonstrates erosions in late stages. Ultrasound (US) has a high overall sensitivity in diagnosing gout with the 'double contour' sign having a high specificity. Magnetic resonance imaging is good at detecting tophi, bone marrow oedema and erosions, but has a limited role in diagnosis because of its high cost and limited availability. Conventional computed tomography (CT) has no role in the routine diagnosis of gout before development of erosions and tophi. A newer technology, dual-energy CT (DECT) has been shown to be able to detect MSU crystals burden with high accuracy. It has a higher specificity and lower sensitivity that US in gout diagnosis. However, because of radiation exposure and cost, it has a better utility in diagnosing clinically suspected gout complicated by other concurrent rheumatologic conditions or if radiography, US and synovial aspiration are inconclusive or not feasible. This paper will review the clinico-pathologic and imaging features of gouty arthropathy.

The concentration of uric acid in patients with metabolic syndrome and cardiovascular diseases

The association of elevated serum uric acid (hyperuricemia, gout) with the presence of classical coronary risk factors and coronary artery disease (CAD) or myocardial infarction (MI) has been analysed in many epidemiological studies. Numerous studies have revealed that hypertension, high body mass index (BMI), lipid disorders (especially raised triglyceride (TG) levels and low high dense lipoprotein cholesterol (HDL-C) level), and increased creatinine or insulin levels have caused hyperuricemia. Gout has often occurred with typical disorders for the metabolic syndrome X. Significant correlation of the serum uric level and the CAD presence and severity of coronary atherosclerosis confirmed by coronary angiography has been observed in women. Hyperuricemia has also indirect influence on progress of CAD by physical activity restriction, what causes sedentary mode of life and lead to obesity. Therefore, we conducted our study in order to estimate uric acid levels in patients with metabolic syndrome and coexisting cardiovascular system diseases.

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.

Inverse association between coffee drinking and serum uric acid concentrations in middle-aged Japanese males

Consumption of caffeine-rich beverages, which have diuretic properties, may decrease serum uric acid concentrations. We examined cross-sectionally the relationship of coffee and green tea consumption to serum uric acid concentrations in 2240 male self-defence officials who received a pre-retirement health examination at four hospitals of the Self-Defence Forces between 1993 and 1994. The mean levels of coffee and green tea consumption were 2·3 and 3·1 cups/d respectively. There was a clear inverse relationship between coffee consumption and serum uric acid concentration. When adjusted for hospital only, those consuming less than one cup of coffee daily had a mean serum uric acid concentration of 60 mg/l, while that of those drinking five or more cups of coffee daily was 56 mg/l (P < 0·0001). No such relationship was observed for green tea, another major dietary source of caffeine in Japan. The relationship between coffee consumption and serum uric acid concentration was independent of age, rank in the Self-Defence Forces, BMI, systolic blood pressure, serum creatinine, serum total cholesterol and serum HDL-cholesterol concentrations, smoking status, alcohol use, beer consumption and intake of dairy products. These findings suggest that coffee drinking may be associated with lower concentrations of serum uric acid, and further studies are needed to confirm the association.

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.

Effect of Aging on Serum Uric Acid Levels: Longitudinal Changes in a Large Japanese Population Group

BACKGROUND

Serum uric acid (SUA) is related not only to an increased risk of gout, but also to an increased risk of cardiovascular diseases. However, real age-related changes in SUA remain unknown.

METHODS

Longitudinal population-based study of epidemiological follow-up data of SUA, body mass index (BMI), and alcohol intake was conducted at a health examination center between 1989 and 1998. The subjects were 80,506 Japanese office workers or their families (50,157 men and 30,349 women) with an average age of 44.5 years for the men and 43.7 years for the women.

RESULTS

SUA increased with age in all birth cohorts examined in men, and in women except for the youngest birth cohort (1960-1969). BMI and alcohol consumption positively contributed to the longitudinal changes of SUA. However, SUA also increased with age in the model controlled for BMI and alcohol consumption. There were birth cohort effects of SUA; at most ages, there were higher SUA levels in younger cohorts in men and lower SUA levels in younger cohorts in women, respectively.

CONCLUSIONS

SUA levels in men and women increased with advancing age, despite changes in drinking and in the BMI. There are birth cohort effects for SUA levels in the Japanese population.

Serum uric acid is not an independent risk factor for coronary heart disease

Many large epidemiologic studies have confirmed a positive association between raised serum uric acid and risk of coronary heart disease or cardiovascular disease, both in the general population and among hypertensive patients. There is much controversy concerning the role of uric acid as an independent risk factor in the development of coronary heart disease because serum uric acid is related to many of the established etiologic risk factors for cardiovascular disease that could confound the observed association. This review finds little support for an independent causal role for serum uric acid in the development of coronary heart disease.

Is hyperuricemia a risk factor of stroke and coronary heart disease among Africans?

BACKGROUND

Uric acid stabilizes platelet aggregation and enhances thrombotic tendency.

OBJECTIVE

To examine the relationship between raised serum uric acid and subsequent cardiovascular events (mortality, myocardial infarction, stroke).

METHODS

This is a longitudinal study in a small random number (418) of patients in Kinshasa, Congo. In this hospital-based study, uricemia was determined with respect to gender, obesity and hypertension as well correlated with traditional cardiovascular risk factors. A univariate regression model was used to investigate the association of serum uric acid with the incidence of mortality, stroke and myocardial infarction.

RESULTS

Serum uric acid was higher (P<0.05) in obese women and men as well in hypertensives, than in their controls. The significant (P<0.05 and 0.001) highest frequency of hyperuricemia was observed in both diabetic and hypertensive patients. Blood pressure (BP) was higher (P<0.001) in patients with hyperuricemia than in those with normal serum uric acid. Serum uric acid was significantly correlated with body weight, BP, glucose, fibrinogen, urea, creatinin and total cholesterol. In men, hyperuricemia was significantly (P<0.01) associated with a twofold increased risk of both myocardial infarction and stroke incidence. However, hyperuricemia was significantly related to a double risk of all mortality and stroke onset.

CONCLUSION

Our results indicate that hyperuricemia among african patients is a strong predictor of myocardial infarction in men, stroke in both sexes and all causes of mortality in women.

Relation between serum triglyceride level, serum urate concentration, and fractional urate excretion

The relations between serum urate levels and age, serum cholesterol, creatinine, glucose, and triglyceride concentrations were studied in 930 men and 298 premenopausal and 478 postmenopausal women, taking into account the renal handling of uric acid. All subjects were outpatients, and statistical evaluation was performed on cases corresponding to the central 95th percentile of the biochemical variables measured. An alternative analysis excluding subjects with serum glucose or creatinine levels outside the normal range was also performed. In men, premenopausal and postmenopausal women, and their normoglycemic normocreatininemic subsets, serum triglyceride level was positively correlated with serum urate concentration and inversely correlated with fractional urate excretion in both simple and multiple linear regression analysis. In men and postmenopausal women, there was also a strong positive independent association between serum urate and creatinine levels. This association was significant also in the normoglycemic normocreatininemic subset of men, but it was insignificant in normoglycemic normocreatininemic postmenopausal women. In this large cross-sectional study, a negative correlation between serum triglyceride concentration and renal uric acid excretion has been demonstrated.

Serum urate and the risk of major coronary heart disease events

OBJECTIVE

To examine the relation between serum urate and the risk of major coronary heart disease events.

DESIGN

A prospective study of a male cohort.

SETTING

One general practice in each of 24 British towns.

SUBJECTS

7688 men aged 40-59 years at screening.

MAIN OUTCOME MEASURES

Fatal and non-fatal coronary heart disease events.

RESULTS

There were 1085 major coronary heart disease events during the average follow up period of 16.8 years. Serum urate was significantly associated with a wide range of cardiovascular risk factors including body mass index, alcohol intake, antihypertensive treatment, pre-existing coronary heart disease, serum triglycerides, cholesterol, and diastolic blood pressure. There was a significant positive association between serum urate and risk of coronary heart disease after adjustment for lifestyle factors and disease indicators. This relation was attenuated to non-significance upon additional adjustment for diastolic blood pressure and serum total cholesterol: cholesterol appeared to be the critical factor in attenuating this relation. When the association between serum urate and risk of coronary heart disease was examined by presence and grade of pre-existing coronary heart disease, a positive association was seen only in men with previous definite myocardial infarction, even after full adjustment (P = 0.07).

CONCLUSIONS

The relation between serum urate and the risk of coronary heart disease depends heavily upon the presence of pre-existing myocardial infarction and widespread underlying atherosclerosis as well as the clustering of risk factors. Thus serum urate is not a truly independent risk factor for coronary heart disease. Raised serum urate appears to be an integral part of the cluster of risk factors associated with the insulin resistance syndrome that include obesity, raised serum triglycerides, and serum cholesterol.

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.

Correlates of uric acid and its association with asymptomatic carotid atherosclerosis: the ARIC Study. Atherosclerosis Risk in Communities

The correlates of serum uric acid and the association of uric acid with carotid intimal-medial thickness (an early measure of atherosclerosis) were investigated in participants of the baseline examination of the Atherosclerosis Risk in Communities (ARIC) Study. The study sample included 6522 women (74% white) and 4966 men (79% white) who were aged 45 to 64 years at baseline (1986-1989). Those with prevalent coronary heart disease or previous stroke and those taking uricosuric medication were excluded. The mean (SD) uric acid concentration was 5.9 (1.5) mg/dL. It was highest among black men 45-54 years old (6.9 [1.5] mg/dL), and lowest in white women aged 45-54 years old (5.0 [1.2] mg/dL). The uric acid level was positively correlated in both sexes with a variety of health-related factors, most notably body mass index, creatinine, triglycerides, diuretic use, alcohol intake, hypertension, diabetes, and insulin levels. In a linear regression model adjusting for age and ARIC center, the level of uric acid was directly and significantly associated with B-mode ultrasound carotid intimal-medial thickness in women and white men (but not in black men). However, when known risk factors for atherosclerotic disease and relevant behavioral and biological correlates of uric acid were controlled for in multivariate analysis, the association of uric acid with this early measure of atherosclerosis became negligible in white women and much weaker and not statistically significant in black women and white men. Thus, uric acid itself may not be a risk factor for atherosclerosis. Future analysis of cardiovascular events in the ARIC Study will further elucidate the role of uric acid in atherosclerotic disease.

Serum uric acid correlates in elderly men and women with special reference to body composition and dietary intake (Dutch Nutrition Surveillance System)

In 460 apparently healthy Dutch elderly, aged 65-79 years, serum uric acid correlates were studied by linear regression analyses, for men and women separately. Diuretic therapy, total serum cholesterol (women only) and creatinine clearance (in bivariate analysis only) were significantly associated with serum uric acid level. Positive associations of serum uric acid with body weight, body mass index, body fatness (men) and lean body mass (men) were observed, with and without adjustment for diuretic therapy, creatinine clearance and age. Serum uric acid levels, whether adjusted or not for these variables and for body mass index, were positively associated with alcohol intake (men) and consumption of meat and fish (women), and inversely with consumption of bread, margarine and milk products (women). These results indicate that limited medication with diuretics, weight control and restriction of alcohol use may help to prevent hyperuricemia in the elderly.

Heberden Oration 1981: epidemiology and the arthritides

The multifactorial control of serum uric acid levels is discussed from an epidemiological point of view and the principles at issue related to the epidemiology of osteoarthrosis. It is shown that in osteoarthrosis the clinical characteristics vary from one joint group to another. Association of x-ray changes with pain varies between joints and between sexes for the various joints. The disease tends to be commoner in females but not in all age groups. There is an association between obesity and osteoarthrosis in the hands and knees but not the hips or ankles. These differences raise questions about the homogeneity of generalised osteoarthrosis. Such questions might be answered by epidemiological studies which consider individual joint groups and are carefully directed towards specific hypotheses, the development of which could be facilitated by the use of iconic models.

The relationship of serum uric acid to hypertension and ischemic heart disease in Hisayama population, Japan

The association of serum uric acid (SUA) with hypertension, ischemic ECG change, diabetes mellitus, and drinking and smoking habits was studied by multivariate analysis among 1871 residents aged 40 and over in Hisayama, Japan. Blood pressure level and history of hypertension did not correlate with an increased level of SUA when other factors such as serum creatinine, obesity, beta-lipoprotein and leucineaminopeptidase were taken into account. Antihypertensive medication was a significant factor influencing SUA. The association of SUA with Minnesota code 4.1-3 (S-T depression) was insignificant in men and significant in women when other factors influencing SUA were taken into account. Glycosuria was negatively correlated with SUA, while alcohol ingestion has positive correlation. There was no correlation between the amount of tobacco smoked and the level of SUA.

Pulse pressure-I. Level and associated factors in four Chicago epidemiologic studies

Because systolic blood pressure rises more sharply than diastolic blood pressure for those middle aged and beyond, leading to an increasing prevalence with advancing age of elevated systolic blood pressure without elevated diastolic pressure, i.e. so-called pure systolic hypertension, the question arises as to whether or not factors that have been shown to be related to blood pressure and hypertension are related to pure systolic hypertension or to 'classical' hypertension, i.e. hypertension defined solely by the level of the diastolic pressure. This question was examined in four Chicago epidemiologic studies by examining the associations between several variables and pulse pressure, with pulse pressure redefined so that the association between a variable and pulse pressure indicated whether the variable was more strongly related to systolic or diastolic blood pressure. In these four studies, glucose, heart rate and cigarette use tended to show a stronger association with systolic pressure, suggesting a possible association with pure systolic hypertension, while hematocrit, serum cholesterol, and uric acid tended to be more strongly associated with diastolic pressure, or equally associated with systolic and diastolic pressure, suggesting an association with 'classical' hypertension. Relative weight tended to be more strongly associated with systolic pressure under the age of 35 and more strongly associated with diastolic pressure after age 45.

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.

Parental smoking related to adenoidectomy and tonsillectomy in children

Histories of adenoïdectomy and tonsillectomy were ascertained, as well as smoking habits of both parents, using questionnaires answered by 3920 schoolchildren aged 10 to 20. Adenoïdectomy and/or tonsillectomy, considered as an index of repeated upper respiratory tract disease in early childhood, was very significantly related to the amount of smoking by each parent. This relationship persisted when age, sex, day nursery attendance, sibship size, and history of appendicectomy were controlled.

The relationship between blood pressure and biochemical risk factors in a general population

The relationship between blood pressure, ponderal index, sex, blood glucose, haemoglobin, serum uric acid, calcium cholesterol and creatinine, and albumin has been examined in 698 subjects aged between 44 and 49 years from the register of a group general practice. Sixty per cent of the variation in systolic pressure could be explained by statistically significant associations with diastolic pressure, sex, blood glucose, serum calcium, and cholesterol. The diastolic blood pressure (not corrected for systolic pressure) was significantly related only to ponderal index, haemoglobin in men, and cholesterol in women. Pulse pressure was also positively related to the risk factors blood glucose, serum cholesterol, and calcium. The possibility is discussed that one or more of these variables reduce aortic compliance and that the serum calcium contributes to this end. Diastolic, but not systolic pressure, had a prime association with relative weight, obesity being only basically associated with an increase in diastolic pressure.

Serum uric acid in hypertensive patients

Both the average serum uric acid and annual increment were determined in 250 treated patients attending a hypertension clinic. The average serum uric acid was greater in men compared with women, in patients receiving a thiazide diuretic and in patients with a high average plasma urea. The mean annual increment in uric acid was close to zero (0.0017 mmol/litre per year) and was not related to sex, age, blood pressure control, diuretic therapy, or plasma urea. There was an unexplained positive association between annual increment and methyldopa therapy though this drug was not associated with a significantly high average serum uric acid. A table is presented giving the theoretical upper limits for average serum uric acid according to sex, plasma urea concentration, and whether or not a thiazide diuretic has been prescribed. It is hoped that this table will be of assistance in assessing the normality or otherwise of a high serum uric acid found in a hypertensive patient.