Absence of an association between serum uric acid and mortality from cardiovascular disease: NIPPON DATA 80, 1980-1994. National Integrated Projects for Prospective Observation of Non-communicable Diseases and its Trend in the Aged

Dose-response relationship of serum uric acid levels with risk of stroke mortality

INTRODUCTION

Results from the recent meta-analysis suggested that higher serum uric acid (SUA) levels are positively associated with risk of stroke. However, the relationship of SUA levels with risk of stroke is still unclear.

MATERIALS AND METHODS

Data from prospective cohort studies on SUA levels and risk of stroke mortality was used. Dose-response relationship was assessed by restricted cubic spline model and multivariate random effect meta-regression.

RESULTS

A non-linear relationship (Pfor non-linearity = 0.004) of SUA levels with risk of stroke mortality was found for men, and the relative risk (RR) with 95% confidence interval (CI) of stroke mortality was 1.00 (0.99-1.01), 0.99 (0.94-1.04), 0.98 (0.91-1.06), 1.00 (0.90-1.12), 1.17 (1.09-1.24) and 1.52 (1.33-1.78) for 2, 3, 4, 5, 6 and 7 mg/dL of SUA levels, respectively. For women, the departure from linearity was not significant (Pfor non-linearity = 0.67), and the RR (95 %CI) of stroke mortality was 1.02 (0.99-1.04), 1.10 (0.97-1.20), 1.15 (0.96-1.37), 1.25 (1.09-1.44), 1.39 (1.28-1.50) for 2, 3, 4, 5, 6 mg/dL of SUA levels, respectively.

CONCLUSIONS

Different dose-response relationships of SUA levels with risk of stroke mortality might exist for men and for women. Dose-response relationship of SUA levels with risk of stroke incidence needs to be explored.

Uric acid is a risk factor for ischemic stroke and all-cause mortality in the general population: a gender specific analysis from The Tromsø Study

BACKGROUND

The role of serum uric acid as an independent predictor of cardiovascular disease and death is uncertain in the general population. Adjustments for additional cardiovascular risk factors have not been consistent. We examined the association of serum uric acid with all-cause mortality, ischemic stroke and myocardial infarction in a prospective population based study, with several traditional and non-traditional risk factors for cardiovascular disease included in the model.

METHODS

A population-based prospective cohort study was performed among 2696 men and 3004 women. Endpoints were all-cause mortality after 15 years, and fatal or non-fatal myocardial infarction (MI) and ischemic stroke after 12 years.

RESULTS

1433 deaths, 659 MIs and 430 ischemic strokes occurred during follow-up. Fully adjusted Cox regression analyses showed that per 1 SD (87 μmol/L) increase in serum uric acid level, the risk of all-cause mortality increased in both genders (hazard ratios, HR men; 1.11, 95% CI 1.02-1.20, women; 1.16, 1.05-1.29). HRs and 95% CI for stroke were 1.31, 1.14-1.50 in men, 1.13, 0.94-1.36 in women, and 1.22 (1.09, 1.35) in the overall population. No independent associations were observed with MI.

CONCLUSION

Serum uric acid was associated with all-cause mortality in men and women, even after adjustment for blood pressure, estimated GFR, urinary albumin/creatinine ratio, drug intake and traditional cardiovascular risk factors. After the same adjustments, serum uric acid was associated with 31% increased risk of stroke in men.

Serum uric acid concentration and asymptomatic hyperuricemia with subclinical organ damage in general population

We assessed the effect of increased serum uric acid (SUA) concentration and hyperuricemia on subclinical organ damage. A cross-sectional examination of 1243 asymptomatic patients aged 55 to 84 years was conducted from September to October 2012. All participants underwent the measurements of SUA and other established cardiovascular (CV) risk factors. A morning spot urine sample was collected to detect microalbuminuria, and carotid plaque was scanned by B-mode ultrasound; the cardioankle vascular index and ankle-brachial index were obtained to evaluate arterial stiffness and peripheral artery disease (PAD), respectively. After adjustment for established CV risk factors, multiple logistic regression analyses showed that the highest quartile of SUA concentration and hyperuricemia had an independent association with PAD (respective odds ratios: 3.86 [1.26-11.83] and 2.33 [1.14-4.77]); this association maintained significantly in males but disappeared in females. Serum uric acid concentration and hyperuricemia are significantly associated with PAD in males.

Hyperuricemia and risk of stroke: a systematic review and meta-analysis of prospective studies

INTRODUCTION

Hyperuricemia may be associated with an increased risk of stroke, but to date results from prospective studies have been inconsistent. This study aimed to evaluate the association between hyperuricemia and risk of stroke incidence and mortality by performing a meta-analysis.

MATERIALS AND METHODS

Studies were identified by searching multiple electronic databases through July 13, 2013, and by reviewing reference lists of obtained articles. Prospective studies reported a multivariate-adjusted estimate, represented as relative risk (RRs) with 95% confidence intervals (CIs) for the association between hyperuricemia and risk of stroke incidence and mortality were eligible. A random-effects model was used to compute the pooled risk estimate.

RESULTS

A total of fourteen articles including results from 15 prospective studies with 22,571 cases of stroke and 1,042,358 participants were included in the meta-analysis. Overall, presence of hyperuricemia was associated with a significantly greater risk of both stroke incidence (RR, 1.22; 95% CI, 1.02-1.46) and mortality (RR, 1.33; 95% CI, 1.24-1.43). In addition, the pooled estimate of multivariate RRs of stroke incidence and mortality were 1.08 (95% CI: 0.85-1.38); 1.26 (95% CI: 1.14-1.40) among men and 1.25 (95% CI: 1.04-1.46); 1.41 (95% CI: 1.31-1.52) among women respectively.

CONCLUSIONS

Results from this meta-analysis indicate that hyperuricemia may modestly increase the risks of both stroke incidence and mortality. Future studies should explore whether hyperuricemia is a modifiable risk factor for stroke.

Relationships between serum uric acid, adiponectin and arterial stiffness in postmenopausal women

OBJECTIVES

Cardiovascular disease (CVD) is a leading cause of death in postmenopausal women. Elevated serum uric acid levels, hypoadiponectinemia and arterial stiffness are strongly associated with cardiovascular diseases. We investigated the relationships among uric acid, adiponectin and arterial stiffness in postmenopausal women.

STUDY DESIGN

9555 subjects who had the routine health check-ups, 841 postmenopausal women aged 50 years or older who had not had a menstrual period for more than 12 consecutive months were included in this study.

MAIN OUTCOME MEASURES

BMI, WC, and serum concentrations of uric acid, adiponectin, glucose, lipids (total cholesterol, triglycerides, LDL cholesterol, and HDL cholesterol) were measured. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment (HOMA-IR). Pulse wave velocity (PWV) was evaluated to assess arterial stiffness.

RESULTS

The subjects were stratified into three groups according to uric acid values. PWV values gradually increased and adiponectin level decreased with uric acid tertiles. Serum uric acid levels in postmenopausal women correlated significantly with age, BMI, WC, TG, HDL-C, insulin, HOMA-IR, adiponectin and PWV. Multiple regression analysis showed that WC (β=0.141, P<0.01), HOMA (β=0.137, P<0.01), adiponectin (β=-0.104, P<0.01), and PWV (β=0.129, P<0.01) were independently correlated with uric acid levels. In multiple logistic regression analysis after adjusting for risk factors, uric acid was a significant contributor to increased PWV.

CONCLUSIONS

These findings indicate that serum uric acid is independently associated with adiponectin and arterial stiffness in postmenopausal women.

Hyperuricemia and hypertension

Over the past century, uric acid has been considered a possible risk factor for hypertension and cardiovascular disease. However, only in the past decade, animal models and clinical trials have supported a more mechanistic link. Results from animal models suggest a 2-phase mechanism for the development of hyperuricemic hypertension in which uric acid induces acute vasoconstriction by activation of renin-angiotensin system, followed by uric acid uptake into vascular smooth muscle cells leading to cellular proliferation and secondary arteriolosclerosis that impairs pressure natriuresis. This acute hypertension remains uric acid dependent and sodium independent, whereas the chronic hypertension becomes uric acid independent and sodium dependent. Small clinical trials, performed in adolescents with newly diagnosed essential hypertension, demonstrate that reduction of serum uric acid can reduce blood pressure. Although more research is clearly necessary, the available data suggest that uric acid is likely causative in some cases of early onset hypertension.

Relationships among hyperuricemia, endothelial dysfunction and cardiovascular disease: molecular mechanisms and clinical implications

Uric acid is the end product of purine metabolism. Its immediate precursor, xanthine, is converted to uric acid by an enzymatic reaction involving xanthine oxidoreductase. Uric acid has been formerly considered a major antioxidant in human plasma with possible beneficial anti-atherosclerotic effects. In contrast, studies in the past two decades have reported associations between elevated serum uric acid levels and cardiovascular events, suggesting a potential role for uric acid as a risk factor for atherosclerosis and related diseases. In this paper, the molecular pattern of uric acid formation, its possible deleterious effects, as well as the involvement of xanthine oxidoreductase in reactive oxygen species generation are critically discussed. Reactive oxygen species contribute to vascular oxidative stress and endothelial dysfunction, which are associated with the risk of atherosclerosis. Recent studies have renewed attention to the xanthine oxidoreductase system, since xanthine oxidoreductase inhibitors, such as allopurinol and oxypurinol, would be capable of preventing atherosclerosis progression by reducing endothelial dysfunction. Also, beneficial effects could be obtained in patients with congestive heart failure. The simultaneous reduction in uric acid levels might contribute to these effects, or be a mere epiphenomenon of the drug action. The molecular mechanisms involved are discussed.

Uric acid is an independent risk factor for carotid atherosclerosis in a Japanese elderly population without metabolic syndrome

Background

Carotid intima-media thickness (IMT) is an useful surrogate marker of cardiovascular disease. Associations between uric acid (UA), metabolic syndrome (MetS) and carotid IMT have been reported, but findings regarding the relationship have been inconsistent.

Methods

A total of 1,579 Japanese elderly subjects aged ≥65 years {663 men aged, 78 ± 8 (mean ± standard deviation) years and 916 women aged 79 ± 8 years} were divided into 4 groups according to UA quartiles. We first investigated the association between UA concentrations and confounding factors including MetS; then, we assessed whether there is an independent association of UA with carotid IMT and atherosclerosis in participants subdivided according to gender and MetS status.

Results

Carotid IMT was significantly increased according to the quartiles of UA in both genders without MetS and women with MetS. Multivariate logistic regression analysis showed that odds ratio (OR) {95% confidence interval (CI)} in men for carotid atherosclerosis was significantly increased in the third (OR, 1.75; 95% CI, 1.02-3.02), and fourth quartiles (OR, 2.01; 95% CI, 1.12-3.60) of UA compared with that in the first quartile of UA, and the OR in women was significantly increased in the fourth quartile (OR, 2.10; 95% CI, 1.30-3.39). Similarly, the ORs were significantly associated with increasing quartiles of UA in both genders without MetS, but not necessarily increased in those with MetS.

Conclusions

UA was found to be an independent risk factor for incidence of carotid atherosclerosis in both genders without MetS.

Management of asymptomatic hyperuricaemia in patients with chronic kidney disease by Japanese nephrologists: a questionnaire survey

AIM

Hyperuricaemia is associated with chronic kidney disease (CKD) progression and cardiovascular events (CVE). In a US study, only 4% of rheumatologists initiated urate-lowering therapy in patients with asymptomatic hyperuricaemia (AHU). The present study aimed to clarify how Japanese board-certified nephrologists manage AHU in CKD patients.

METHODS

Questionnaires on management of AHU in CKD stage 3 or more were mailed to 1500 Japanese board-certified nephrologists, excluding paediatricians and urologists, randomly selected from the directory of the Japanese Society of Nephrology (n = 2976).

RESULTS

Five hundred and ninety-five nephrologists (40%) responded. Most nephrologists (84-89%) recommended that AHU in patients in CKD stages 3-5 should be treated, but fewer nephrologists (63%) recommended that AHU in patients of CKD stage 5D should be treated. The serum urate level to start urate-lowering therapy and the target serum urate level to be achieved (mg/dL) were 8.2 ± 0.9 and 6.9 ± 0.9, 8.4 ± 0.9 and 7.0 ± 1.0, 8.6 ± 1.0 and 7.3 ± 1.1, and 9.1 ± 1.2 and 7.8 ± 1.3 at stages 3, 4, 5 and 5D, respectively. The most frequently used maximal dosage of allopurinol was 100 mg/day at each stage. Benzbromarone was used in 52% of patients at stage 3, but only in 29%, 13% and 5% of patients at stages 4, 5 and 5D, respectively. The most important reasons to treat AHU at CKD stages 3-5 were prevention of CKD progression (45%), CVE (33%), gout (18%) and urolithiasis (3%).

CONCLUSION

Most Japanese nephrologists treat AHU in pre-dialysis CKD with an aim to prevent CKD progression or CVE mainly by allopurinol.

The biological relevance of direct antioxidant effects of polyphenols for cardiovascular health in humans is not established

Human studies provide evidence for beneficial effects of polyphenol-rich foods on cardiovascular health. The antioxidant activity of polyphenols potentially explains these effects, but is the antioxidant activity a reliable predictor for these effects? An International Life Sciences Institute Europe working group addressed this question and explored the potential of antioxidant claims for polyphenols in relation to cardiovascular health by using the so-called Process for the Assessment of Scientific Support for Claims on Foods project criteria. In this process, analytical aspects of polyphenols, their occurrence in foods, dietary intake, and bioavailability were reviewed. Human studies on polyphenols and cardiovascular health were reviewed together with methods for biomarkers of oxidative damage and total antioxidant capacity (TAC). In retrospective studies, F2-isoprostanes and oxidized LDL, the most reliable biomarkers of lipid peroxidation, and measures for TAC showed the expected differences between cardiovascular disease patients and healthy controls, but prospective studies are lacking, and a causal relationship between these biomarkers and cardiovascular health could not be established. Therefore, the physiological relevance of a potential change in these biomarkers is unclear. We found limited evidence that some types of polyphenol-rich products modify these biomarkers in humans. A direct antioxidant effect of polyphenols in vivo is questionable, however, because concentrations in blood are low compared with other antioxidants and extensive metabolism following ingestion lowers their antioxidant activity. Therefore, the biological relevance of direct antioxidant effects of polyphenols for cardiovascular health could not be established. Overall, although some polyphenol-rich foods exert beneficial effects on some biomarkers of cardiovascular health, there is no evidence that this is caused by improvements in antioxidant function biomarkers (oxidative damage or antioxidant capacity).

Serum uric acid does not predict cardiovascular or all-cause mortality in type 2 diabetes: the Fremantle Diabetes Study

AIMS/HYPOTHESIS

To determine whether serum uric acid: (1) is associated with cardiovascular disease (CVD) death and/or all-cause mortality in type 2 diabetes; and (2) consistent with published data, predicts these outcomes in older patients and those of southern European ethnicity.

METHODS

We studied those 1,268 (98%) of 1,294 type 2 participants in the observational Fremantle Diabetes Study who had a fasting serum uric acid measured at baseline. Mortality data were collected over a mean (+/-SD) 10.3 +/- 3.9 years. Cox proportional hazards modelling was used to determine independent baseline predictors of CVD and all-cause death including fasting serum uric acid as a continuous variable and quartiles.

RESULTS

During follow up, 525 deaths occurred (41.4% of the cohort) of which 271 (51.6%) were attributed to CVD. In univariate analyses, patients in the highest uric acid quartile had the greatest CVD and all-cause mortality (p = 0.007 and p = 0.001). After adjustment for significant variables in the most parsimonious model, baseline serum uric acid was not an independent associate of CVD or all-cause mortality whether entered as a continuous variable (HR 1.11 [95% CI 0.96-1.27] and 1.10 [95% CI 0.98-1.22] for a 0.1 mmol/l increase, respectively) or as quartiles (p > 0.10). Analyses of 638 patients >65 years of age and 231 of southern European ethnicity produced similar results.

CONCLUSIONS/INTERPRETATION

Serum uric acid was not an independent predictor of CVD or all-cause mortality in our community-based type 2 patients. Fasting serum uric acid concentrations do not appear to be prognostically useful in type 2 diabetes.

Is high serum uric acid a risk marker or a target for treatment? Examination of its independent effect in a large cohort with low cardiovascular risk

BACKGROUND

Cohort studies evaluating increased uric acid level as a cardiovascular disease (CVD) risk factor have shown variable results; studies are particularly lacking in lower risk populations.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

484,568 adults participating in a medical screening program in Taiwan since 1994 were followed up for a median of 8.5 years. Two subgroups were constructed: the first (n = 246,697; 51%) excluded participants with either overt CVD or overt CVD risk factors (including hypertension, diabetes, obesity, and hypertriglyceridemia) and the second (n = 157,238; 32%) further excluded individuals with early-stage CVD risk factors (including prehypertension, prediabetes, overweight, and borderline hypertriglyceridemia).

PREDICTOR

Serum uric acid.

OUTCOMES & MEASUREMENTS

All-cause and CVD mortality risk assessed using Cox proportional hazards models for categorical and continuous serum uric acid levels. As applicable, models adjusted for 14 variables. Population-attributable fraction was applied to compare contributions to mortality between high uric acid level and other CVD risk factors.

RESULTS

In the total cohort, mean age was 41.4 +/- 14.0 years and 26.2% had serum uric acid levels >or=7 mg/dL. Through 2007, there were 16,246 deaths (3.4% of all participants), with 35.2% of deaths occurring in individuals with hyperuricemia. Adjusted HRs associated with serum uric acid levels >or=7 mg/dL for all-cause and CVD mortality were 1.10 (95% CI, 1.04-1.17) and 1.38 (95% CI, 1.20-1.58), respectively. In individuals with hyperuricemia, 64.3% had overt CVD risk factors and 82.5% had either overt or early-stage CVD risk factors. Individuals with serum uric acid levels >or=8 mg/dL without overt CVD risk factors constituted 13.5% of the total study population with hyperuricemia; in analyses excluding those with overt CVD risk factors, serum uric acid level >or=8 mg/dL was significantly associated with all-cause and CVD mortality, with HRs of 1.37 (95% CI, 1.18-1.60) and 2.30 (95% CI, 1.51-3.49), respectively. In the subgroup of those with serum uric acid levels >or=8 mg/dL but who lacked both overt and early-stage CVD risk factors, the HRs for all-cause and CVD mortality were also significant and were 1.39 (95% CI, 1.08-1.78) and 2.38 (95% CI, 1.24-4.54), respectively. HRs for individuals with the same risk profiles but with serum uric acid of 7.0-7.9 mg/dL were not significant. In all groups, inclusion of proteinuria and glomerular filtration rate in models substantially attenuated the association between uric acid level and outcomes. High uric acid levels contributed a relatively insignificant portion to mortality (1.2%) and CVD deaths (4.5%) in this population.

LIMITATIONS

A single measurement of uric acid was used.

CONCLUSION

Increased serum uric acid level is a minor, but significant, risk factor for all-cause and CVD mortality. However, except for a small proportion (13.5%), increased serum uric acid level is more a risk marker than a target for treatment and is not an independent risk. Determining appropriate groups to target in clinical trials for uric acid-lowering therapy is critical.

Calcium intake and associated factors in a general Japanese population: baseline data of NIPPON DATA80/90 and the National Nutrition Survey

Objective

The purpose of this study was to investigate the dietary calcium intake and associated other dietary factors among representative sample of Japanese general men and women.

Methods

Data was obtained by linking NIPPON DATA80 and 90 with the corresponding National Nutrition Surveys held in 1980 and 1990. We analyzed data for 10 422 subjects (4585 men and 5837 women) in NIPPON DATA80 and 8342 subjects (3488 men and 4854 women) in NIPPON DATA90. Calcium intake was calculated by age groups. Dietary calcium intake was classified into quintiles and physical, life-style, and dietary parameters were examined across the quintiles.

Results

For both men and women, calcium intake tended to be positively associated with age in NIPPON DATA80 and 90, and there were significant differences in estimated calcium intake between age groups. Calcium intake tended to be positively associated with age, protein, fat, saturated fat, vitamins A and C, sodium, potassium, and iron for men and women. Calcium intake also tended to be positively associated with intake of nuts, potatoes, sugar and sweeteners, soybeans and legumes, fruits, green and yellow vegetables, other vegetables, mushrooms, sea algae, fish and shellfish, eggs, and milk and dairy products for men and women.

Conclusions

The characteristics of calcium intake in Japanese people were able to be clarified by using the baseline data of NIPPON DATA and the National Nutrition Survey.

Hyperuricemia and risk of stroke: a systematic review and meta-analysis

OBJECTIVE

To assess the association between hyperuricemia and risk of stroke incidence and mortality because hyperuricemia is hypothesized to be a risk factor for stroke and other cardiovascular disease, but, to date, results from observational studies are conflicting.

METHODS

A systematic review and meta-analysis were conducted. Studies were identified by searching major electronic databases using the Medical Subject Headings and keywords without restriction in languages. Prospective cohort studies were included only if they contained data on stroke incidences or mortalities related to serum uric acid levels in adults. Pooled risk ratios (RRs) for the association of stroke incidence and mortality with serum uric acid levels were calculated.

RESULTS

A total of 16 studies including 238,449 adults were eligible and abstracted. Hyperuricemia was associated with a significantly higher risk of both stroke incidence (6 studies; RR 1.41, 95% confidence interval [95% CI] 1.05, 1.76) and mortality (6 studies; RR 1.36, 95% CI 1.03, 1.69) in our meta-analyses of unadjusted study estimates. Subgroup analyses of studies adjusting for known risk factors such as age, hypertension, diabetes mellitus, and cholesterol still showed that hyperuricemia was significantly associated with both stroke incidence (4 studies; RR 1.47, 95% CI 1.19, 1.76) and mortality (6 studies; RR 1.26, 95% CI 1.12, 1.39). The pooled estimate of multivariate RRs did not differ significantly by sex.

CONCLUSION

Hyperuricemia may modestly increase the risks of both stroke incidence and mortality. Future research is needed to determine whether lowering uric acid level has any beneficial effects on stroke.

Association between hyperuricemia and incident heart failure among older adults: a propensity-matched study

BACKGROUND

The association between hyperuricemia and incident heart failure (HF) is relatively unknown.

METHODS

Of the 5461 community-dwelling older adults, >or=65 years, in the Cardiovascular Health Study without HF at baseline, 1505 had hyperuricemia (baseline serum uric acid >or=6 mg/dL for women and >or=7 mg/dL for men). Using propensity scores for hyperuricemia, estimated for each participant using 64 baseline covariates, we were able to match 1181 pairs of participants with and without hyperuricemia.

RESULTS

Incident HF occurred in 21% and 18% of participants respectively with and without hyperuricemia during 8.1 years of mean follow-up (hazard ratio {HR} for hyperuricemia versus no hyperuricemia, 1.30; 95% confidence interval {CI}, 1.05-1.60; P=0.015). The association between hyperuricemia and incident HF was significant only in subgroups with normal kidney function (HR, 1.23; 95% CI, 1.02-1.49; P=0.031), without hypertension (HR, 1.31; 95% CI, 1.03-1.66; P=0.030), not receiving thiazide diuretics (HR, 1.20; 95% CI, 1.01-1.42; P=0.044), and without hyperinsulinemia (HR, 1.35; 95% CI, 1.06-1.72; P=0.013). Used as a continuous variable, each 1 mg/dL increase in serum uric acid was associated with a 12% increase in incident HF (HR, 1.12; 95% CI, 1.03-1.22; P=0.006). Hyperuricemia had no association with acute myocardial infarction or all-cause mortality.

CONCLUSIONS

Hyperuricemia is associated with incident HF in community-dwelling older adults. Cumulative data from our subgroup analyses suggest that this association is only significant when hyperuricemia is a marker of increased xanthine oxidase activity but not when hyperuricemia is caused by impaired renal elimination of uric acid.

The role of uric acid in stroke: the issue remains unresolved

BACKGROUND

Although in the past decade a large number of studies have been performed to identify the relationship between uric acid and stroke, the issue remains unresolved and it is not clear whether the correlation between uric acid and stroke is circumstantial or causal.

REVIEW SUMMARY

Some studies have found uric acid predictive for the development of cardiovascular disease, whereas others have failed to identify uric acid as a significant and independent risk factor after controlling for other atherosclerotic risk factors. Furthermore, uric acid, a powerful endogenous antioxidant, is increased in oxidative stress situations such as stroke. Still, it remains controversial whether elevated serum uric acid is neuroprotective or injurious at the onset of acute stroke.

CONCLUSIONS

Large trials are required to provide definite answers in clinical practice and to reevaluate the goals of hypouricemic treatment in subjects with increased cardiovascular risk or during an acute cardiovascular event like stroke. This review tries to keep pace with the data concerning the association between uric acid and stroke.

Serum uric acid is an independent predictor for all major forms of cardiovascular death in 28,613 elderly women: a prospective 21-year follow-up study

BACKGROUND

The role of serum uric acid (SUA) as a risk factor for cardiovascular disease (CVD) remains controversial. Little is known about its predictive value for mortality from congestive heart failure (CHF) and stroke, particularly in elderly, post-menopausal women.

METHODS

The relation of SUA to risk of death from total CVD, CHF, stroke and coronary heart disease (CHD) was examined prospectively in a large cohort of 28613 elderly Austrian women (mean age 62.3 years), followed-up for a median of 15.2 years. Adjusted Cox proportional hazards models were calculated to evaluate SUA as an independent predictor for fatal CVD events.

RESULTS

SUA in the highest quartile (>or=5.41 mg/dL) was significantly associated with mortality from total CVD (p<0.0001), showing a clear dose-response relationship; the adjusted hazard ratio (95%CI) in comparison to the lowest SUA quartile was 1.35 (1.20-1.52). In subgroup analyses SUA was independently predictive for deaths from acute and subacute (p<0.0001) and chronic forms (p=0.035) of CHD, yielding adjusted hazard ratios for the highest versus lowest SUA quartile of 1.58 (1.19-2.10) and 1.25 (1.01-1.56), respectively. SUA was further significantly related to fatal CHF (p<0.0001) and stroke (p=0.018); the adjusted hazard ratios for the highest versus lowest SUA quartile were 1.50 (1.04-2.17) and 1.37 (1.09-1.74), respectively.

CONCLUSIONS

These findings, for the first time, demonstrate that SUA is an independent predictor for all major forms of death from CVD including acute, subacute and chronic forms of CHD, CHF and stroke in elderly, post-menopausal women.

Serum uric acid and risk of cardiovascular mortality: a prospective long-term study of 83,683 Austrian men

BACKGROUND

The role of serum uric acid (SUA) as an independent risk factor for cardiovascular disease (CVD) remains controversial, and little is known about its prognostic importance for mortality from congestive heart failure (CHF) and stroke. Few large-scale epidemiologic studies with sufficient follow-up have addressed the association of SUA and CVD mortality in apparently healthy men across a wide age range.

METHODS

A cohort of 83 683 Austrian men (mean age, 41.6 years) was prospectively followed for a median of 13.6 years. We used Cox proportional hazards models adjusted for established risk factors to evaluate SUA as an independent predictor for CVD mortality.

RESULTS

The highest quintile of SUA concentration (>398.81 mumol/L) was significantly related to mortality from CHF (P = 0.03) and stroke (P <0.0001); adjusted hazard ratios (95% confidence interval) for the highest vs lowest quintiles of SUA were 1.51 (1.03-2.22) and 1.59 (1.23-2.04), respectively. SUA was not associated, however, with mortality from acute, subacute, or chronic forms of coronary heart disease (CHD) after adjustment for potential confounding factors (P = 0.12). Age was a significant effect modifier for the relation of SUA to fatal CHF (P = 0.05), with markedly stronger associations found in younger individuals.

CONCLUSIONS

Our study demonstrates for the first time in a large prospective male cohort that SUA is independently related to mortality from CHF and stroke. Although increased SUA is not necessarily a causal risk factor, our results suggest the clinical importance of monitoring and intervention based on the presence of an increased SUA concentration, especially because SUA is routinely measured.

Genome scan for determinants of serum uric acid variability

Elevated serum uric acid level is associated with obesity, insulin resistance, diabetes, nephropathy, and hypertension. Epidemiologic studies suggest that serum uric acid levels are heritable. We sought to identify chromosomal regions harboring quantitative trait loci that influence serum uric acid in Mexican Americans using data from 644 participants in the San Antonio Family Heart Study. Serum uric acid was found to exhibit significant heritability (0.42) in this population (P = 2 x 10(-7)) after accounting for covariate effects. In addition, genetic correlations between serum uric acid and other cardiovascular risk factors, such as body mass index, waist circumference, systolic BP, and pulse pressure, were identified, suggesting that the genes associated with uric acid level are also associated with these phenotypes. Multipoint linkage analysis identified quantitative trait loci with measurable effects on serum uric acid variability. The highest multipoint logarithm of odds score of 3.3 was found at 133 cM on chromosome 6q22-23, a region that also contains genes that seem to influence familial IgA nephropathy, obesity, BP, insulin resistance, and type 2 diabetes. Given the relationship between uric acid level and these conditions, future studies should investigate potential candidate susceptibility genes found in this region.

Serum uric acid as a risk factor for cardiovascular and renal disease: an old controversy revived

Hyperuricemia is commonly associated with traditional risk factors such as abnormalities in glucose metabolism, dyslipidemia, and hypertension. Recent studies have revived the controversy over the role of serum uric acid as an independent prognostic factor for cardiovascular mortality. The authors review clinical and experimental evidence concerning the role of serum uric acid in the development of cardiovascular and renal damage. Results of trials suggesting that serum uric acid variations over time may have a prognostic impact are also discussed.

Serum uric acid and risk of ischemic stroke: The ARIC Study

AIMS

Since serum uric acid (UA) is strongly associated with cardiovascular risk factors, it has been debated whether serum UA is a stroke risk factor or whether UA may be simply "marking" subjects with other, causal risk factors. We therefore investigated the relation between UA and ischemic stroke in the Atherosclerosis Risk in Communities (ARIC) Study.

METHODS AND RESULTS

Of 15,792 ARIC participants, 13,413 who were free of recognized stroke or coronary heart disease (CHD) at baseline and had a baseline UA measurement were included in the analysis. We followed the participants for ischemic stroke incidence (N=381) over 12.6 years. Although serum UA was independently and positively related to ischemic stroke incidence when we adjusted for age, sex, race, and education, the positive relation was weakened when additionally adjusted for possible confounding variables. The positive multivariate-adjusted association between serum UA and ischemic stroke was observed among subjects not using diuretics (adjusted relative hazard in the highest quartile versus the lowest: relative hazard (RH)=1.49; 95% confidence interval (CI): 1.00-2.23) (P for trend: 0.02), but not among diuretic users (P for interaction: 0.08).

CONCLUSION

Our findings suggest that UA is an independent predictor of ischemic stroke among subjects not using diuretics, but that elevated UA itself may not cause ischemic stroke.

Proteinuria is a prognostic marker for cardiovascular mortality: NIPPON DATA 80, 1980-1999

BACKGROUND: Proteinuria has been considered to be a prognostic marker for persons with diabetes mellitus, but only a limited number of studies about the relationship between proteinuria and mortality among general population has been available.

METHODS: The subjects were 10,897 individuals who participated in the National Cardiovascular Survey conducted in 1980 and who were aged 30 years or older living in 300 districts that had been randomly selected throughout Japan. The vital records were confirmed in 1999 and 7,203 subjects (3,180 males and 4,023 females) without a history of hypertension, stroke, heart disease, renal disease, or diabetes mellitus at the start of the study were investigated.

RESULTS: There were 126,825 person-years of follow-up. During the observed period of time, 371 died of cardiovascular causes, including 171 stroke deaths and 74 coronary deaths. The risk of proteinuria for cardiovascular mortality was greater than unity for those with a normal serum creatinine level, after adjusting for age and other cardiovascular disease risk factors.

CONCLUSIONS: When contrasted with other cardiovascular disease risk factors, urinary protein is an independent risk factor for cardiovascular death among the Japanese population.

A nineteen-year cohort study on the relationship of electrocardiographic findings to all cause mortality among subjects in the national survey on circulatory disorders, NIPPON DATA80

BACKGROUND: Electrocardiogram (ECG) is one of the most popular tools for daily clinics and health checkup, and has been used for the National Survey on Circulatory Disorders to assess the health status in Japanese people. The meaningfulness to predict mortality from all causes among people with ECG abnormality is to be clarified using national samples.

METHODS: ECG findings recorded among 9,638 subjects for National Survey on Circulatory Disorders 1980 in Japan, were classified using the Minnesota Codes (mc). Their relationships to all cause mortality over 19 years were examined using Cox proportional hazard models adjusting for sex, age, systolic blood pressure, blood glucose, and smoking habits.

RESULTS: Subjects with abnormal Q-QS findings showed significantly high hazard ratios ( 3.71(mc1-1) and 1.57 (mc1-3)) for mortality to the subjects who were free from any major ECG findings. Hazard ratios were 1.37 (mc2-1) to 4.16 (mc2-5) for axis deviation, and 1.34 (mc3-1) to 1.35 (mc3-3) for left high R waves. Those were 1.63 (mc4-3) to 2.59 (mc4-1) for ST depression, and 1.54 (mc5-3) to 2.33 (mc5-1) for T abnormality. The lower the second number of the Minnesota Codes was, the higher hazard ratio was observed in the Q-QS, ST, T codes. The hazard ratios of junction-type ST depression (mc4-4), and low T waves (mc5-4, 5-5) were not significant.

CONCLUSIONS: ECG findings defined by the Minnesota Codes were useful to predict the risk for mortality from all causes even after adjusting for the other major risk factors, and the results supported a usefulness of the ECG for health check-ups.

The increase in serum uric acid concentration caused by diuretics might be beneficial in heart failure

Patients with mild-moderate chronic heart failure (CHF) often have raised levels of serum uric acid (UA). This is due, amongst other factors, to reduced UA excretion by the kidneys, which is partly explained by restriction of sodium intake and treatment with diuretics. The decline in renal function that parallels worsening cardiac function also contributes to elevated serum UA in patients with advanced CHF. However, UA production also appears to be augmented in CHF. Because UA scavenges various reactive oxygen species, diuretic-induced elevations in serum UA could be beneficial in patients with CHF. This concept is supported by the superior performance of antihypertensive therapy with diuretics in preventing heart failure. The present hypothesis may be tested by examining the effects of add-on treatment with a thiazide-type diuretic on morbidity and mortality, or surrogate variables, in asymptomatic patients with left ventricular dysfunction but without fluid retention.

Serum uric acid and target organ damage in primary hypertension

The role of serum uric acid as an independent risk factor for cardiovascular and renal morbidity is controversial. A better understanding of its relationship with preclinical organ damage may help clarify the mechanism(s) implicated in the development of early cardiovascular disease. We evaluated the association between uric acid and the presence and degree of target organ damage in 425 (265 males, 160 females) middle-aged, untreated patients with essential hypertension. Left ventricular mass index and carotid intima-media thickness were assessed by ultrasound scan. Albuminuria was measured as the albumin to creatinine ratio in 3 nonconsecutive first morning urine samples. Overall, patients with target organ damage had significantly higher levels of serum uric acid as compared with those without it (presence versus absence of left ventricular hypertrophy, P=0.04; carotid abnormalities, P<0.05; microalbuminuria, P<0.004; and at least 1 versus no organ damage, P<0.03). In women, the occurrence and severity of each target organ damage we examined increased progressively from the lower to the upper serum uric acid tertiles (P<0.01). After adjustment for body mass index, age, creatinine clearance, and high-density lipoprotein cholesterol, each standard deviation increase in serum uric acid entailed a 75% higher risk of having cardiac hypertrophy and a 2-times greater risk of having carotid abnormalities. These results support the role of serum uric acid as an independent, modifiable marker of cardiovascular damage.

Association between fish consumption and all-cause and cause-specific mortality in Japan: NIPPON DATA80, 1980-99

PURPOSE

Although high consumption of fish may be one of the contributing factors for Japanese longevity, no epidemiological study using Japanese data has tested this hypothesis.

SUBJECTS AND METHODS

The relationship between fish consumption and all-cause as well as cause-specific mortality was analyzed using the database of NIPPON DATA80. At baseline in 1980, history, physical, and blood biochemical measurement and a nutritional survey by the food-frequency method were performed in randomly selected community-based subjects aged 30 years and over in Japan. After exclusion of subjects with significant comorbidities at baseline, we followed 3945 men and 4934 women for 19 years. Men and women were analyzed comprehensively. Age- and sex-adjusted and multivariate adjusted relative risk for all-cause or cause-specific mortality was calculated using a Cox proportional hazards model with delayed entry.

RESULTS

During 19 years of followup, there were 1745 deaths. Subjects were divided into 5 groups according to fish consumption frequency. The multivariate Cox analyses showed that relative risks for subjects who ate fish more than twice daily compared with those of subjects who ate 1 to 2 times weekly were 0.99 (95% confidence intervals: 0.77-1.27) for all-cause, 1.26 (0.70-2.29) for stroke, 0.92 (0.20-4.23) for cerebral hemorrhage, 1.09 (0.48-2.43) for cerebral infarction, and 0.91 (0.35-2.35) for coronary heart disease mortality.

CONCLUSION

Our results did not provide evidence in support of the fish hypothesis, perhaps because the majority of the Japanese subjects in the study ate fish more than the threshold level shown to be beneficial in the previous studies.

The effect of alcoholic beverage type on hyperuricemia in Japanese male office workers

BACKGROUND

The association between alcohol consumption and risk of hyperuricemia has been pointed out. However, the potential difference in the risk of hyperuricemia according to types of alcoholic beverage has not been assessed.

METHODS

A cross-sectional survey was performed using data from 715 men who had regular medical examinations in their workplace in 2001. Subjects were interviewed using a questionnaire about their lifestyle including types of alcoholic beverages and quantity of alcohol consumed per day. Logistic regression analysis was performed to assess the relationship between the types of alcoholic beverage and high serum uric acid level.

RESULTS

Compared with subjects who did not drink alcohol, the odds ratio (OR) of hyperuricemia (serum uric acid = 7.0+ mg/dL) was 2.89 (95% confidence interval [CI]: 1.46-5.71) for subjects who consumed 50+ g/day of ethanol, and 2.64 (95% CI: 1.33-5.24) for subjects who consumed 25-49g/day. Compared with subjects who drank Japanese sake, subjects who drank beer (OR=1.24, 95% CI: 0.55-2.80) or shochu (OR=1.06, 95% CI: 0.44-2.51) did not have a statistically significant difference in risk for hyperuricemia.

CONCLUSION

These findings from a cross-sectional study of Japanese male office workers suggested that alcohol consumption is associated with an increased risk of hyperuricemia and that this increased risk does not vary according to the types of alcoholic beverage.

Serum uric acid and risk of death from cancer, cardiovascular disease or all causes in men

OBJECTIVE

Although many epidemiological studies have suggested that increased serum uric acid levels are a risk factor for mortality, this relationship remains uncertain. This cohort study examined the effects of serum uric acid level on death from cancer, atherosclerotic cardiovascular disease (ASCVD) or all causes in men.

METHOD

A 9-year, prospective cohort study was carried out with 22698 Korean men, aged 30 to 77 years, who received health insurance from the National Health Insurance Corporation and who underwent biennial, secondary medical evaluations in 1992-1996. The main outcome measures were death from cancer, ASCVD or all causes, compared by quintiles of serum uric acid level. At baseline, the mean (SD) level of serum uric acid was 354.4 (98.1) micromol/l.

RESULTS

During 199746 person-years of follow-up, there were 387 cancer deaths, 323 ASCVD (99 ischaemic heart disease, 192 stroke) deaths and 1625 all-cause deaths. In multivariate Cox proportional hazards models, having controlled for age, current smoking, diabetes, hypertension and hypercholesterolaemia, uric acid levels were not associated with mortality from cancer, ASCVD or all causes. However, for those with diabetes, uric acid levels were associated with mortality from all causes even after full adjustment of the covariates. When the interaction term was included in the multivariate model, there was significant interactive effect of uric acid with diabetes (RR=1.26, 95% confidence interval 1.02-1.55) on the risk of all cause of death, whereas the effects of uric acid itself did not attain significance.

CONCLUSION

These findings indicate that uric acid level is not an independent risk factor for death from cancer, ASCVD or all causes.

A combination of serum low albumin and above-average cholesterol level was associated with excess mortality

BACKGROUND

There is no population-based prospective study concerning the relation between serum albumin and mortality in a non-Western population, and few previous studies included the subgroup analysis stratified by serum cholesterol level.

METHODS

A 13.7-year cohort study was conducted on 6,957 males and females aged 30-59 years from 300 randomly selected areas throughout Japan, who participated in the National Survey on Circulatory Disorders in 1980.

RESULTS

In the group with median and above of total cholesterol, one standard deviation (SD) increment of serum albumin (2.6 g/L for males and 2.4 g/L for females) was inversely associated with all-cause mortality for both males and females (relative risk RR = 0.68 and 0.81: 95% confidence interval CI = 0.53-0.87 and 0.68-0.98), and with cancer mortality for females (RR = 0.74; 95% Cl = 0.57-0.96);and the lowest category of serum albumin (< or = 43 g/L) showed the highest cardiovascular mortality for males (RR = 5.04; 95% CI = 1.04-24.5) among the three albumin categories. These relationships were not evident in the group with total cholesterol level below median.

CONCLUSION

A combination of a low albumin level and above average cholesterol level, even both within the clinical normal range,is associated with excess mortality in the Japanese general population.

Egg consumption, serum cholesterol, and cause-specific and all-cause mortality: the National Integrated Project for Prospective Observation of Non-communicable Disease and Its Trends in the Aged, 1980 (NIPPON DATA80)

BACKGROUND

Because egg yolk has a high cholesterol concentration, limited egg consumption is often suggested to help prevent ischemic heart disease (IHD).

OBJECTIVE

We epidemiologically examined the validity of this recommendation.

DESIGN

We analyzed the relations of egg consumption to serum cholesterol and cause-specific and all-cause mortality by using the NIPPON DATA80 (National Integrated Project for Prospective Observation of Non-communicable Disease And its Trends in the Aged, 1980) database. At the baseline examination in 1980, a nutritional survey was performed by using the food-frequency method in Japanese subjects aged > or =30 y. We followed 5186 women and 4077 men for 14 y.

RESULTS

The subjects were categorized into 5 egg consumption groups on the basis of their responses to a questionnaire (> or =2/d, 1/d, 1/2 d, 1-2/wk, and seldom). There were 69, 1396, 1667, 1742, and 315 women in each of the 5 groups, respectively. Age-adjusted total cholesterol (5.21, 5.04, 4.95, 4.91, and 4.92 mmol/L in the 5 egg consumption categories, respectively) was related to egg consumption (P < 0.0001, analysis of covariance). In women, unadjusted IHD mortality and all-cause mortality differed significantly between the groups [IHD mortality: 1.1, 0.5, 0.4, 0.5, and 2.0 per 1000 person-years, respectively (P = 0.008, chi-square test); all-cause mortality: 14.8, 8.0, 7.5, 7.5, and 14.5 per 1000 person-years, respectively (P < 0.0001, chi-square test)]. In men, egg consumption was not related to age-adjusted total cholesterol. Cox analysis found that, in women, all-cause mortality in the 1-2-eggs/wk group was significantly lower than that in the 1-egg/d group, whereas no such relations were noted in men.

CONCLUSION

Limiting egg consumption may have some health benefits, at least in women in geographic areas where egg consumption makes a relatively large contribution to total dietary cholesterol intake.

Resting heart rate and cause-specific death in a 16.5-year cohort study of the Japanese general population

BACKGROUND

Several prospective studies have reported resting heart rate (HR) to be a risk factor for certain cause-specific death, together with sex- or age-specific differences in the effects of HR on death. However, there have been few prospective data from non-Western populations.

METHODS

Cohort study, over 16.5 years to date of death or end of follow-up (November 15, 1998) involving 8800 men and women > or =30 years of age randomly selected throughout Japan, who participated in the National Survey on Circulatory Disorders in 1980. Resting HR was determined from 3 consecutive intervals between R waves on the 12-lead electrocardiogram.

RESULTS

For middle-aged men (30 to 59 years of age), in the highest quartile of HR, there was a significant positive association with cardiovascular (RR, 2.55; 95% CI, 1.22 to 5.31) and all-cause death (RR, 1.45; 95% CI, 1.06 to 2.00). For middle-aged women, in the highest quartile, there was a significant positive association with noncancer, noncardiovascular (RR, 2.41; 95% CI, 1.04 to 5.59), and all-cause death (RR, 1.94; 95% CI, 1.26 to 3.01). Resting HR also showed a significant positive association with cardiac events but not to stroke. These relations were not evident for elderly subjects (> or =60 years of age). Results were not affected when deaths within the first 5 years of follow-up were excluded, except for noncancer, noncardiovascular death.

CONCLUSIONS

High resting HR is an independent predictor of long-term death in the Japanese general population.

What cause of mortality can we predict by cholesterol screening in the Japanese general population?

OBJECTIVE

In a population with a markedly lower coronary mortality such as in Japan, the benefit of cholesterol screening may be different from Western populations. We attempted to assess the importance of cholesterol screening in Japan.

DESIGN

A 13.2-year cohort study for cause-specific mortality.

SETTING

Three hundred randomly selected districts throughout Japan in which the National Survey on Circulatory Disorders 1980 was performed.

SUBJECTS

A total of 9216 community dwelling persons aged 30 years and over, with standardized serum cholesterol measurement and without a past history of cardiovascular disease.

RESULTS

There were 1206 deaths, which included 462 deaths due to cardiovascular disease with 79 coronary heart diseases. Hypercholesterolemia (>6.21 mmol L-1) showed a significant positive relation to coronary mortality (relative risk; 2.93, 95% confidence interval; 1.52-5.63) but not to stroke. Although hypocholesterolemia (<4.14 mmol L-1) was significantly associated with an increased risk of liver cancer, noncardiovascular, noncancer disease and all-cause mortality, these associations, except for liver cancer, disappeared after excluding deaths in the first 5 years of the follow-up. The multivariate adjusted attributable risk of hypercholesterolaemia for coronary disease was 0.98 per 1000 person-years, which was threefold higher than that of hypocholesterolemia for liver cancer: 0.32 per 1000 person-years. The attributable risk percentage of hypercholesterolaemia was 66% for coronary heart disease.

CONCLUSION

Similar to Western populations, it is recommended to provide screening for hypercholesterolaemia in Japan, especially for males, although its attributable risk for coronary disease might be small.