A gender-specific analysis of association between hyperuricaemia and cardiovascular events in patients with coronary artery disease

Uric Acid Levels, Number of Standard Modifiable Cardiovascular Risk Factors, and Prognosis in Patients With Coronary Artery Disease: A Large Cohort Study in Asia

Background Serum uric acid (UA) is correlated closely with traditional cardiovascular risk factors, which might interfere with the action of UA, in patients with coronary artery disease. We performed this study to evaluate the prognostic effect of UA levels in individuals with different numbers of standard modifiable cardiovascular risk factors (SMuRFs). Methods and Results In this prospective study, we consecutively enrolled 10 486 patients with coronary artery disease. They were stratified into 3 groups according to the tertiles of UA concentrations and, within each UA tertile, further classified into 3 groups by the number of SMuRFs (0-1 versus 2-3 versus 4). The primary end point was major adverse cardiovascular and cerebrovascular events (MACCEs), including death, myocardial infarction, stroke, and unplanned revascularization. Over a median follow-up of 2.4 years, 1233 (11.8%) MACCEs were recorded. Patients with high UA levels developed significantly higher risk of MACCEs than those with low UA levels. In addition, UA levels were positively associated with MACCEs as a continuous variable. More importantly, in patients with 0 to 1 SMuRF, the risks of MACCEs were significantly higher in the high-UA-level group (adjusted hazard ratio [HR], 1.469 [95% CI, 1.197-1.804]) and medium-UA-level group (adjusted HR, 1.478 [95% CI, 1.012-2.160]), compared with the low-UA-level group, whereas no significant association was found between UA levels and the risk of MACCEs in participants with 2 to 3 or 4 SMuRFs. Conclusions In patients with coronary artery disease who received evidence-based secondary prevention therapies, elevated UA levels might affect the prognosis of individuals with 0 to 1 SMuRF but not that of individuals with ≥2 SMuRFs.

Serum uric acid levels threshold for mortality in diabetic individuals: The URic acid Right for heArt Health (URRAH) project

BACKGROUND AND AIM

The URRAH (URic acid Right for heArt Health) Study has identified cut-off values of serum uric acid (SUA) predictive of total mortality at 4.7 mg/dl, and cardiovascular (CV) mortality at 5.6 mg/dl. Our aim was to validate these SUA thresholds in people with diabetes.

METHODS AND RESULTS

The URRAH subpopulation of people with diabetes was studied. All-cause and CV deaths were evaluated at the end of follow-up. A total of 2570 diabetic subjects were studied. During a median follow-up of 107 months, 744 deaths occurred. In the multivariate Cox regression analyses adjusted for several confounders, subjects with SUA ≥5.6 mg/dl had higher risk of total (HR: 1.23, 95%CI: 1.04-1.47) and CV mortality (HR:1.31, 95%CI:1.03-1.66), than those with SUA <5.6 mg/dl. Increased all-cause mortality risk was shown in participants with SUA ≥4.7 mg/dl vs SUA below 4.7 mg/dl, but not statistically significant after adjustment for all confounders.

CONCLUSIONS

SUA thresholds previously proposed by the URRAH study group are predictive of total and CV mortality also in people with diabetes. The threshold of 5.6 mg/dl can predict both total and CV mortality, and so is candidate to be a clinical cut-off for the definition of hyperuricemia in patients with diabetes.

Probiotic Characterization of Lactobacillus brevis MJM60390 and In Vivo Assessment of Its Antihyperuricemic Activity

Uric acid is the final product of purine metabolism in human. The increase of serum uric acid is tightly related to the incidence of hyperuricemia and gout. Also, it has been reported that the intake of purine-rich foods like meat and seafood is associated with an increased risk of gout. Therefore, the reduction of purine absorption is one of therapeutic approaches to prevent hyperuricemia and gout. Currently, probiotics are being studied for the management of hyperuricemia and gout. In this study, we aimed to investigate the effect of Lactobacillus brevis MJM60390 on hyperuricemia induced by a high-purine diet and potassium oxonate in a mouse model. L. brevis MJM60390 among 24 lactic acid bacteria isolated from fermented foods showed the highest ability to assimilate inosine and guanosine in vitro and typical probiotic characteristics, like the absence of bioamine production, D-lactate production, hemolytic activity, as well as tolerance to simulated orogastrointestinal conditions and adherence to Caco-2 cells. In an in vivo animal study, the uric acid level in serum was significantly reduced to a normal level after oral administration of L. brevis MJM60390 for 2 weeks. The activity of xanthine oxidase catalyzing the formation of uric acid was also inhibited by 30%. Interestingly, damage to the glomerulus, Bowman's capsule, and tubules in the hyperuricemia model were reversed by supplementation with this strain. Fecal microbiome analysis revealed that L. brevis MJM60390 supplementation enhanced the relative abundance of the Rikenellaceae family, which produces the short-chain fatty acid butyrate and helps to maintain good gut condition. Therefore, these results demonstrated that L. brevis MJM60390 can be a probiotic candidate to prevent hyperuricemia.

Mediating Effect of Body Mass Index and Dyslipidemia on the Relation of Uric Acid and Type 2 Diabetes: Results From China Health and Retirement Longitudinal Study

Objective

This study assessed temporal relationships of serum uric acid (SUA) with blood glucose and determine the mediating effects of body mass index (BMI) and dyslipidemia on the relation of SUA and risk of type 2 diabetes.

Methods

Participants aged ≥ 45 years were participated in 2011 and followed up until 2015. Cox proportional hazards regression with a robust variance estimator was performed to explore the association of SUA with the risk of diabetes, and crosslagged path analysis was introduced to examine the temporal relationships between SUA and blood glucose. A mediation analysis was finally used to identify the mediating effect of BMI and dyslipidemia on the relation of SUA and the future risk of diabetes.

Results

A total of 9,020 participants were included with an average age of 58.59 years at baseline in 2011, and 53.6% of them were women. Linear dose–response relationship was identified by restricted spline cubic analysis between baseline SUA and follow-up blood glucose (the non-linear trend for fasting plasma glucose (FPG): β2 = −0.71, p = 0.52; for HbA1c: β2 = 0.05, p = 0.07; for risk of diabetes: β2 = 0.12, p = 0.39). Additionally, compared with the lowest quartiles of SUA, the adjusted risk ratios of diabetes were 1.00 (95% CI: 0.82–1.23), 1.08 (95% CI: 0.89–1.31), and 1.37 (95% CI: 1.11–1.96) for quartile 2–4 (p-trend &lt; 0.01), respectively. Further additional adjustments for BMI or dyslipidemia, these ratios were not statistically significant. In addition, a unidirectional relationship from baseline SUA to follow-up FPG (ρ1 = 0.24, p = 0.03) was further confirmed using crosslagged path analysis. After stratifying by genders, the above results were only significant in the women subgroup, and we thus conducted a mediation analysis in women and found that the BMI and dyslipidemia partially mediated the effect of SUA on diabetes with a 23.05 and 18.82% mediating effect, respectively.

Conclusions

These findings provide strong evidence that hyperuricemia preceded diabetes, and the effect of baseline SUA on follow-up type 2 diabetes was more pronounced among middle-aged and elderly Chinese women, especially in postmenopausal women, and this effect is partly mediated by BMI and dyslipidemia at baseline.

Role of asymptomatic hyperuricemia in the progression of chronic kidney disease and cardiovascular disease

Previous research has investigated whether hyperuricemia serves as an independent risk factor for cardiovascular and renal diseases. Hyperuricemia is defined as an abnormally high level of uric acid (UA; i.e., serum urate level > 6.8 mg/dL). Hyperuricemia has been considered a complication of chronic kidney disease (CKD). However, it seems to play a pathogenic role in the progression of renal diseases. There has been increasing focus on the link between hyperuricemia and CKD. The results of randomized controlled trials have implied independent associations between hyperuricemia and the progression of cardiovascular and renal morbidities. These associations may be mediated by renin-angiotensin system activation, nitric oxide synthase inhibition, and macrovascular/microvascular disease development. There remains controversy regarding the use of serum UA level as an indirect index of renal vascular disease. This literature review focuses on the role of asymptomatic hyperuricemia in the progression of CKD, as well as the association between hyperuricemia and cardiovascular disease. It also provides a general overview of the physiological metabolism of UA.

Sex-specific differences and long-term outcome of patients with coronary artery disease and chronic kidney disease: the Coronary Artery Disease and Renal Failure (CAD-REF) Registry

BACKGROUND

Cardiovascular morbidity and mortality are closely linked to chronic kidney disease (CKD). Sex-specific long-term outcome data of patients with coronary artery disease (CAD) and CKD are scarce.

METHODS

In the prospective observational multicenter Coronary Artery Disease and REnal Failure (CAD-REF) Registry, 773 (23.1%) women and 2,579 (76.9%) men with angiographically documented CAD and different stages of CKD were consecutively enrolled and followed for up to 8 years. Long-term outcome was evaluated using survival analysis and multivariable Cox-regression models.

RESULTS

At enrollment, women were significantly older than men, and suffered from more comorbidities like CKD, hypertension, diabetes mellitus, and multivessel coronary disease. Regarding long-term mortality, no sex-specific differences were observed (Kaplan-Meier survival estimates: 69% in women vs. 69% in men, plog-rank = 0.7). Survival rates decreased from 89% for patients without CKD at enrollment to 72% for patients with CKD stages 1-2 at enrollment and 49% for patients with CKD stages 3-5 at enrollment (plog-rank < 0.001). Cox-regression analysis revealed that sex or multivessel coronary disease were no independent predictors of long-term mortality, while age, CKD stages 3-5, albumin/creatinine ratio, diabetes, valvular heart disease, peripheral artery disease, and left-ventricular ejection fraction were predictors of long-term mortality.

CONCLUSIONS

Sex differences in CAD patients mainly exist in the cardiovascular risk profile and the extent of CAD. Long-term mortality was not depended on sex or multivessel disease. More attention should be given to treatment of comorbidities such as CKD and peripheral artery disease being independent predictors of death. Clinical Trail Registration ClinicalTrials.gov Identifier: NCT00679419.

Association Between Uric Acid, Carotid Intima-Media Thickness, and Cardiovascular Events: Prospective Results From the IMPROVE Study

Background The association between elevated serum uric acid (SUA), cardiovascular disease (CVD) risk, and carotid atherosclerosis has long been explored, and contrasting results have been reported. Therefore, the role of SUA as an independent risk factor for vascular events (VEs) and carotid atherosclerosis deserves further attention. We investigated the relationship between SUA, incident VEs, carotid intima-media thickness (cIMT), and cIMT progression in subjects at moderate-to-high CVD risk. Methods and Results In the IMPROVE (IMT-Progression as Predictors of VEs) study, 3686 participants (median age 64 years; 48% men) with ≥ 3 vascular risk factors, free from VEs at baseline, were grouped according to SUA quartiles (division points: 244-284-328 µmol/L in women, 295-336-385 µmol/L in men). Carotid-IMT and its 15-month progression, along with incident VEs, were recorded. A U-shaped association between SUA and VEs was observed in men, with 2.4-fold (P = 0.004) and 2.5-fold (P = 0.002) increased CVD risk in the first and fourth SUA quartiles as compared with the second. Adjusted hazard ratios (HRs) for cerebro-VEs in men were the highest (first and fourth quartile versus second: HR, 5.3, P = 0.010 and HR, 4.4, P = 0.023, respectively). SUA level was independently associated with cIMT progression in men (β = 0.068, P = 0.014). No significant association between SUA levels, CVD end points, and cIMT progression were found in women. Conclusions Both low and high SUA levels are associated with an increased risk of VEs in men at moderate-to-high CVD risk but not in women. Only elevated SUA levels predict cIMT progression and at a lesser but not significant extent in women.

Gender Differences in the Association Between Serum Uric Acid and Arteriosclerotic Cardiovascular Risk Among Chinese Type 2 Diabetes Mellitus Patients

Background and Objectives

Serum uric acid (sUA) level has been reported to be associated with arteriosclerotic cardiovascular risk, yet remains poorly defined in Chinese type 2 diabetes patients. The purpose of the current study was to evaluate gender differences in the association between sUA level and arteriosclerotic cardiovascular risk in Chinese type 2 diabetes patients.

Methods

The cross-sectional study was conducted in six community health service centers in Shanghai, China from December 2014 to December 2016. A stratified random sampling method was used to recruit participants. From a total of 3977 type 2 diabetic patients, 2537 were included for the analysis of the association between sUA level and arteriosclerotic cardiovascular risk. Clinical and biochemical data were obtained from participants. Arteriosclerotic cardiovascular risk was evaluated by the ten-year risk profile for arteriosclerotic cardiovascular disease. The associations between sUA level and arteriosclerotic cardiovascular risk were assessed via multiple logistic regression.

Results

Of the 2537 participants, the average sUA level was 317±77umol/L in men and 294±73 umol/L in women, and 54.8% (1391/2537) of participants had high ten-year risk of arteriosclerotic cardiovascular disease (ASCVD), which was ≥20%. High ten-year risk of ASCVD odds ratio was increased by 1.596 (95% CI, 1.113-2.289, p for trend 0.004) comparing fourth to first quartiles of sUA in women. However, no significant association was found between sUA and high ten-year risk of ASCVD in men.

Conclusion

This community-based study indicated that sUA levels were independently associated with high ten-year risk of ASCVD in women with type 2 diabetes mellitus, but not in men.

Serum uric acid and fatal myocardial infarction: detection of prognostic cut-off values: The URRAH (Uric Acid Right for Heart Health) study

Supplemental Digital Content is available in the text

Objective:

The Working Group on Uric Acid and Cardiovascular Risk of the Italian Society of Hypertension conceived and designed an ad-hoc study aimed at searching for prognostic cut-off values of serum uric acid (SUA) in predicting fatal myocardial infaction (MI) in women and men.

Methods:

The URic acid Right for heArt Health study is a nationwide, multicentre, observational cohort study involving data on individuals aged 18–95 years recruited on a regional community basis from all the territory of Italy under the patronage of the Italian Society of Hypertension with a mean follow-up period of 122.3 ± 66.9 months.

Results:

A total of 23 467 individuals were included in the analysis. Cut-off values of SUA able to discriminate MI status were identified by mean of receiver operating characteristic curves in the whole database (>5.70 mg/dl), in women (>5.26 mg/dl) and in men (>5.49 mg/dl). Multivariate Cox regression analyses adjusted for confounders (age, arterial hypertension, diabetes, chronic kidney disease, smoking habit, ethanol intake, BMI, haematocrit, LDL cholesterol and use of diuretics) identified an independent association between SUA and fatal MI in the whole database (hazard ratio 1.381, 95% confidence intervals, 1.096–1.758, P = 0.006) and in women (hazard ratio 1.514, confidence intervals 1.105–2.075, P < 0.01), but not in men.

Conclusion:

The results of the current study confirm that SUA is an independent risk factor for fatal MI after adjusting for potential confounding variables, and demonstrate that a prognostic cut-off value associated to fatal MI can be identified at least in women.

Hyperuricemia and Risk of Cardiovascular Outcomes: The Experience of the URRAH (Uric Acid Right for Heart Health) Project

The latest European Guidelines of Arterial Hypertension have officially introduced uric acid evaluation among the cardiovascular risk factors that should be evaluated in order to stratify patient's risk. In fact, it has been extensively evaluated and demonstrated to be an independent predictor not only of all-cause and cardiovascular mortality, but also of myocardial infraction, stroke and heart failure. Despite the large number of studies on this topic, an important open question that still need to be answered is the identification of a cardiovascular uric acid cut-off value. The actual hyperuricemia cut-off (> 6 mg/dL in women and 7 mg/dL in men) is principally based on the saturation point of uric acid but previous evidence suggests that the negative impact of cardiovascular system could occur also at lower levels. In this context, the Working Group on uric acid and CV risk of the Italian Society of Hypertension has designed the Uric acid Right for heArt Health project. The primary objective of this project is to define the level of uricemia above which the independent risk of CV disease may increase in a significantly manner. In this review we will summarize the first results obtained and describe the further planned analysis.

Long-term prognostic impact of hyperuricemia in community

The debate whether an elevated level of serum uric acid (SUA) is an independent marker of cardiovascular risk is still going on. We examined morbidity and mortality related to SUA and hyperuricemia in a well-characterized population with very long follow-up. Study included 4696 participants (aged 30-59 years at baseline) of the coronary heart disease (CHD) Study of the Finnish Mobile Clinic Health Examination Survey. Adjusted hazard ratios (HRs) of hyperuricemia (defined as ≥360 µmol/l and ≥420 µmol/l) and SUA quintiles for mortality and adverse cardiovascular outcomes are reported. During the mean follow up of 30.6 years there were 2723 deaths, 887 deaths for CHD of which 340 were classified as sudden cardiac deaths, 1642 hospitalizations due to CHD and 798 hospitalizations due to congestive heart failure. After adjusting to baseline risk factors and presence of cardiovascular diseases as well as the use of diuretics there were no significant differences in the risk of any of the outcomes when analyzed either according to quintiles of SUA or using a cut-off point SUA ≥360 µmol/l for hyperuricemia. Only a rare finding of hyperuricemia SUA ≥420 µmol/l among women (n = 17, 0.9%) was independently associated with significantly higher risk of mortality (adjusted HR: 2.59, 95% CI: 1.54-4.34) and a combination end-point of major adverse cardiac events (MACEs) (HR: 2.69; 95% CI: 1.56-4.66). SUA was not an independent indicator of morbidity and mortality, with the exception of particularly high levels of SUA among women.

Uric acid and cardiovascular disease

Uric acid (UA) is an end product of purine metabolism in humans and great apes. UA acts as an antioxidant and it accounts for 50% of the total antioxidant capacity of biological fluids in humans. When present in cytoplasm of the cells or in acidic/hydrophobic milieu in atherosclerotic plaques, UA converts into a pro-oxidant agent and promotes oxidative stress and through this mechanism participates in the pathophysiology of human disease including cardiovascular disease (CVD). Most epidemiological studies but not all of them suggested the existence of an association between elevated serum UA level and CVD, including coronary heart disease (CHD), stroke, congestive heart failure, arterial hypertension and atrial fibrillation as well as an increased risk for mortality due to CVD in general population and subjects with confirmed CHD. Evidence available also suggests an association between elevated UA and traditional cardiovascular risk factors, metabolic syndrome, insulin resistance, obesity, non-alcoholic fatty liver disease and chronic kidney disease. Experimental and clinical studies have evidenced several mechanisms through which elevated UA level exerts deleterious effects on cardiovascular health including increased oxidative stress, reduced availability of nitric oxide and endothelial dysfunction, promotion of local and systemic inflammation, vasoconstriction and proliferation of vascular smooth muscle cells, insulin resistance and metabolic dysregulation. Although the causality in the relationship between UA and CVD remains unproven, UA may be pathogenic and participate in the pathophysiology of CVD by serving as a bridging mechanism mediating (enabling) or potentiating the deleterious effects of cardiovascular risk factors on vascular tissue and myocardium.

Knockout of the urate oxidase gene provides a stable mouse model of hyperuricemia associated with metabolic disorders

The urate oxidase (Uox) gene encodes uricase that in the rodent liver degrades uric acid into allantoin, forming an obstacle for establishing stable mouse models of hyperuricemia. The loss of uricase in humans during primate evolution causes their vulnerability to hyperuricemia. Thus, we generated a Uox-knockout mouse model on a pure C57BL/6J background using the transcription activator-like effector nuclease (TALEN) technique. These Uox-knockout mice spontaneously developed hyperuricemia (over 420 μmol/l) with about 40% survival up to 62 weeks. Renal dysfunction (elevated serum creatinine and blood urea nitrogen) and glomerular/tubular lesions were observed in these Uox-knockout mice. Male Uox-knockout mice developed glycol-metabolic disorders associated with compromised insulin secretion and elevated vulnerability to streptozotocin-induced diabetes, whereas female mice developed hypertension accompanied by aberrant lipo-metabolism. Urate-lowering drugs reduced serum uric acid and improved hyperuricemia-induced disorders. Thus, uricase knockout provides a suitable mouse model to investigate hyperuricemia and associated disorders mimicking the human condition, suggesting that hyperuricemia has a causal role in the development of metabolic disorders and hypertension.

Hyperuricemia and clustering of cardiovascular risk factors in the Chinese adult population

Hyperuricemia is common in China and the relevance of hyperuricemia and cardiovascular disease (CVD) risk has been highlighted, but to date there has been rarely nation-wide study in China. Here, we aim to estimate the current prevalence of hyperuricemia and evaluate the associations between hyperuricemia and cardiovascular risk factors (CRFs) clustering in a large sample of China adults including a plurality of ethnic minorities. Generally, a nationally representative sample of 22983 adults aged ≥18 years was recruited from 2007 to 2011. Questionnaire data and information on anthropometric characteristics, and laboratory measurements were collected. We define hyperuricemia as SUA ≥416 mmol/L for men and SUA ≥357 mmol/L for women. We found that the prevalence of hyperuricemia was 13.0% (18.5% in men and 8.0% in women). To our estimation, hyperuricemic subjects had higher prevalence rates of CRFs clustering than non-hyperuricemic subjects. Furthermore, there was a dose-response association between the number of CVD risk factors clustering and hyperuricemia. Our study revealed a high prevalence of hyperuricemia and CVD risk factors clustering among Chinese adults, and hyperuricemia was significantly associated with coexistence of more CVD risk factors. Therefore, guidance and effective lifestyle intervention are required to prevent hyperuricemia and CVD risk factors in China.

Serum uric acid is not independently associated with plasma renin activity and plasma aldosterone in hypertensive adults

BACKGROUND AND AIMS

In experimental investigations conducted in rats, raising serum uric acid (SUA) levels resulted in the stimulation of intrarenal renin expression. Studies in humans exploring the association of SUA with plasma renin activity (PRA) yielded conflicting results. Moreover, little is known about the relationship of SUA with plasma aldosterone concentration (PAC). The study aimed to assess the relationship between SUA levels, PRA, and PAC and the influence of age, gender, body mass index (BMI), and hyperuricemia on these relationships in subjects with essential hypertension (EH).

METHODS AND RESULTS

We enrolled 372 hypertensive patients (mean age 45 ± 12 years, men 67%) with uncomplicated EH that was not pharmacologically treated. The study population was divided in tertiles according to SUA levels. While PRA did not differ significantly across the three tertiles, PAC was higher in subjects belonging to the uppermost tertile of SUA than those in the lower ones (p = 0.0429); however, this difference lost statistical significance after adjustment for age, sex, BMI, and serum creatinine. Univariate correlation analyses showed significant associations of SUA with PRA (r = 0.137; p = 0.008) and PAC (r = 0.179; p < 0.001). However, these relationships were not significant after correcting for confounding factors in multiple linear regression analyses. We did not observe statistically significant effect modification by gender, age, BMI, and hyperuricemia.

CONCLUSION

SUA levels are weakly associated with PRA and PAC in adults with untreated EH. These relationships were lost after adjustment for age, sex, BMI, and serum creatinine.

Association of serum uric acid with subsequent arterial stiffness and renal function in normotensive subjects

Serum uric acid (SUA) is correlated with an increased risk of not only gout but also cardiovascular diseases. The present study aimed to longitudinally evaluate the effects of SUA level on renal function and arterial stiffness in a population-based sample of normotensive subjects. The subjects completed a health checkup in 2002 at baseline and in 2011 or 2012 at the end of the follow-up period. A total of 407 normotensive subjects (171 men and 236 women) aged 26-66 years were enrolled in this study. We measured blood pressure (BP), brachial-ankle pulse wave velocity (baPWV), central BP, intima-media thickness, SUA level and estimated glomerular filtration rate (eGFR). We divided the subjects into four subgroups according to the SUA quartile at baseline and compared renal function and arterial stiffness after the follow-up. The cutoff values were 3.6, 4.4, 5.6 and 9.6 mg dl^-1. The SUA levels associated with baPWV (Q1, 1324; Q2, 1457; Q3, 1442; Q4, 1489 cm s^-1), systolic BP (SBP) (Q1, 110.9; Q2, 110.1; Q3, 112.8; Q4. 116.1 mm Hg) and eGFR (P for trend <0.001). There was a significant difference in the incidence of arterial stiffness in women. Multivariate regression analyses showed that after adjusting for potential confounders, including age, sex, body mass index, SBP and lipids, SUA was a significant determinant of baPWV (β=0.117; P<0.05) and eGFR (β=-0.335, P<0.001). The results of this study suggest that elevated SUA levels may be associated with a higher risk of increased arterial stiffness and reduced renal function in normotensive subjects.

Sex-specific Relationship of Serum Uric Acid with All-cause Mortality in Adults with Normal Kidney Function: An Observational Study

OBJECTIVE

To explain the clinical effect of serum uric acid (SUA) levels as a risk factor for mortality, considering exclusion of kidney function.

METHODS

Participants aged over 40 years who underwent health checkups were recruited. Individuals with estimated glomerular filtrations rates < 60 ml/min/1.73 m² and who received laboratory study and colonoscopy on the same day were excluded.

RESULTS

SUA levels were higher in men than in women (5.7 ± 1.2 mg/dl for men and 4.2 ± 0.9 mg/dl for women, p < 0.001). During 12.3 ± 3.6 years of followup, 1402 deaths occurred among 27,490 participants. About 6.9% of men and 3.1% of women died. The overall mortality rate had a U-shaped association with SUA levels, a U-shaped association in men, and no association in women. There was a significant interaction of sex for the SUA-mortality association (p for interaction = 0.049); therefore, survival analysis was conducted by sex. In men, the lower SUA group had a higher mortality rate after adjustment (SUA ≤ 4.0 mg/dl, adjusted HR 1.413, 95% CI 1.158-1.724, p = 0.001) compared with the reference group (SUA 4.1-6.0 mg/dl). A higher SUA contributed to an insignificant increased mortality in men (> 8.0 mg/dl, adjusted HR 1.140, 95% CI 0.794-1.636, p = 0.479). Women failed to show any significant association between SUA and mortality.

CONCLUSION

This study provided novel evidence that SUA-mortality association differed by sex. We demonstrated that a lower SUA was an independent risk factor for all-cause mortality in men with normal kidney function.

Serum uric acid and the risk of cardiovascular and renal disease

Substantial evidence suggests that chronic hyperuricemia is an independent risk factor for hypertension, metabolic syndrome, chronic kidney disease (CKD) and cardiovascular diseases. This highlights the need for greater attention to serum uric acid levels when profiling patients, and suggests that the threshold above which uricemia is considered abnormal is 6  mg/dl, in light of the available evidence. Another important question is whether lowering serum uric acid can improve cardiovascular and renal outcomes, and what therapeutic mechanism of action could provide more clinical benefits to patients; the available literature shows a trend toward improvement associated with administration of urate-lowering drugs, in particular for the xanthine oxidase inhibitors. The demonstrated efficacy of urate-lowering therapy on outcomes other than gout flares leads to the consideration that treatment may be beneficial even in the absence of overt gout when hyperuricemia accompanies other clinical conditions, such as urate deposition, advanced CKD or cardiovascular risk factors.

Gender differences for uric acid as predictor of hard events in patients referred for coronary angiography

Aim: To assess gender differences in uric acid (UA) as predictor for hard events (HE, mortality and nonfatal myocardial infarction) in a large cohort of patients referred for coronary angiography. Design & patients: 3020 inpatients (2177 males, age: 68 ± 9 years, mean ± SD) were retrospectively studied, collecting data from the Institute electronic databank which included demographic, clinical, instrumental and follow-up data. Results: Although the Kaplan–Meier survival estimates showed a significantly worst outcome in female patients, high UA did not remained a significant predictor for HE after adjustment. Moreover, UA correlated with antioxidant capacity in both sexes. Conclusion: Hyperuricemia was not an independent risk for HE, and being correlated with antioxidant capacity, its elevation appears more likely compensatory than causative for HE.

Association between Serum Uric Acid and Mortality among Chinese Patients with Coronary Artery Disease

OBJECTIVES

Several studies have investigated the association between serum uric acid (SUA) and the risks of coronary artery disease (CAD) but have yielded inconsistent results. The aim of this study was to assess whether there is an independent association of SUA with all-cause and cardiovascular disease (CVD) mortality in Chinese patients with CAD.

METHODS

A prospective cohort study of 1,799 patients was conducted. Cox regression models were used to estimate the association of SUA with the risk of death.

RESULTS

During a median follow-up of 3.9 years, 177 deaths were recorded and 126 of these were due to CVD. Patients in the highest SUA quartile had a 2.43-fold risk of all-cause mortality and a 2.44-fold risk of CVD mortality compared with those in the lowest quartile. In the subpopulation analysis, the association between SUA and mortality remained similar when participants were stratified by age, gender, body mass index and type of CAD. In contrast, we found a significant interaction with estimated glomerular filtration rate (eGFR). There was a stronger association between SUA and the risk of all-cause and CVD mortality among patients with an eGFR ≥60 ml/min/1.73 m2, but no significant association was found in the population with an eGFR <60 ml/min/1.73 m2.

CONCLUSIONS

Elevated SUA levels were positively associated with an increased risk of all-cause and CVD mortality among CAD patients.

Uric Acid for Cardiovascular Risk: Dr. Jekyll or Mr. Hide?

Uric acid (UA) is a potent endogenous antioxidant. However, high concentrations of this molecule have been associated with cardiovascular disease (CVD) and renal dysfunction, involving mechanisms that include oxidative stress, inflammatory processes, and endothelial injury. Experimental and in vitro results suggest that this biomarker behaves like other antioxidants, which can shift from the physiological antioxidant action to a pro-oxidizing effect according to their level and to microenvironment conditions. However, data on patients (general population or CAD cohorts) are controversial, so the debate on the role of hyperuricemia as a causative factor for CVD is still ongoing. Increasing evidence indicates UA as more meaningful to assess CVD in women, even though this aspect needs deeper investigation. It will be important to identify thresholds responsible for UA “biological shift” from protective to harmful effects in different pathological conditions, and according to possible gender-related differences. In any case, UA is a low-tech and inexpensive biomarker, generally performed at patient’s hospitalization and, therefore, easily accessible information for clinicians. For these reasons, UA might represent a useful additive tool as much as a CV risk marker. Thus, in view of available evidence, progressive UA elevation with levels higher than 6 mg/dL could be considered an “alarm” for increased CV risk.

Serum uric acid predicts cardiovascular mortality in male peritoneal dialysis patients with diabetes

BACKGROUND AND AIMS

Serum uric acid may predict mortality in diabetic patients and dialysis patients. However, the relationship between serum uric acid and prognosis in diabetic peritoneal dialysis (PD) patients is unclear.

METHODS AND RESULTS

We conducted a cohort study of 1278 incident PD patients, (mean age 47.6 years), of which 328 (25.7%) had diabetes and 289 (22.6%) had diabetic nephropathy. During a median follow-up period of 30.7 months, 231 deaths occurred, of which 126 were ascribed to cardiovascular events. Mean serum uric acid was lower for diabetic patients than non-diabetic patients (6.8 ± 1.3 vs. 7.4 ± 1.4 mg/dL, respectively; P < 0.001). Cox regression models were adjusted for glycated hemoglobin, dialysis-related factors, traditional risk factors, and treatments. After adjustments, the highest sex-specific tertile of uric acid was associated with an increased risk of cardiovascular mortality (HR, 2.26; 95% CI, 1.14-4.48) compared to the lowest tertile in diabetic patients. Adjusted HRs per 1 mg/dL higher uric acid for all-cause and cardiovascular mortality were 1.09 (95% CI, 0.91-1.32) and 1.42 (95% CI, 1.13-1.79) for diabetic men and 1.06 (95% CI, 0.83-1.35) and 1.12 (95% CI, 0.78-1.61) for diabetic women, respectively. Elevated serum uric acid predicted a higher risk of all-cause and cardiovascular mortality in non-diabetic men but not in non-diabetic women.

CONCLUSIONS

Elevated serum uric acid is an independent predictor of cardiovascular mortality in diabetic male PD patients.

Uric Acid: A Missing Link Between Hypertensive Pregnancy Disorders and Future Cardiovascular Disease?

OBJECTIVE

To determine whether women who had a hypertensive pregnancy disorder (HPD) have elevated uric acid concentrations decades after pregnancy as compared with women who had normotensive pregnancies.

PATIENTS AND METHODS

The Genetic Epidemiology Network of Arteriopathy study measured uric acid concentrations in Hispanic (30%), non-Hispanic white (28%), and non-Hispanic black (42%) women (mean age, 60 ± 10 years). This cross-sectional study was conducted between July 1, 2000, and December 31, 2004. Hispanic participants were recruited from families with high rates of diabetes, whereas non-Hispanic participants were recruited from families with high rates of hypertension. This analysis compared uric acid concentrations in women with a history of normotensive (n = 1846) or hypertensive (n = 408) pregnancies by logistic regression.

RESULTS

Women who had an HPD had higher uric acid concentrations (median, 5.7 mg/dL vs 5.3 mg/dL; P < .001) and were more likely to have uric acid concentrations above 5.5 mg/dL (54.4% vs 42.4%; P = .001) than were women who had normotensive pregnancies. These differences persisted after adjusting for traditional cardiovascular risk factors, comorbidities, and other factors that affect uric acid concentrations. A family-based subgroup analysis comparing uric acid concentrations in women who had an HPD (n = 308) and their parous sisters who had normotensive pregnancies (n = 250) gave similar results (median uric acid concentrations, 5.7 mg/dL vs 5.2 mg/dL, P = 0.02; proportion of women with uric acid concentrations > 5.5 mg/dL, 54.0% vs 40.3%, P < .001).

CONCLUSION

Decades after pregnancy, women who had an HPD have higher uric acid concentrations. This effect does not appear to be explained by a familial predisposition to elevated uric acid concentrations.

Impact of sex on uric acid levels and its relationship with the extent of coronary artery disease: A single-centre study

BACKGROUND

Serum uric acid (SUA) elevation has been largely addressed in the past as a possible risk factor for cardiovascular disease. However, uric acid has not clearly emerged as independent risk factor for coronary artery disease. Several studies in literature have assessed sex-related differences in the association between elevated SUA levels and cardiovascular events with conflicting results. Therefore, aim of the current study was to evaluate the relationship between uric acid levels and the extent of coronary artery disease in male and female patients undergoing coronary angiography.

METHODS

Our population is represented by 3520 consecutive patients undergoing coronary angiography from March 2007 to October 2012. Patients were divided according to Tertiles of SUA (Males, Group 1, ≤5.5 mg/dL-0.33 mmol/mol, n = 762, Group 2, 5.5-6.8 mg/dL-0.33-0.40 mmol/mol, n = 829 and Group 3 ≥6.8 mg/dL-0.40 mmol/mol, n = 851), (Females, Group 1, ≤4.8 mg/dL-0.28 mmol/mol, n = 349, Group 2, 4.8-6.3 mg/dL-0.28-0.37 mmol/mol, n = 359 and Group 3 ≥ 6.3 mg/dL-0.37 mmol/mol, n = 370). Fasting samples were collected for uric acid levels assessment. Coronary disease was defined for at least 1 vessel stenosis >50% as evaluated by QCA. Severe coronary disease was defined as three-vessel disease and/or left main disease.

RESULTS

Among 3520 patients, we identified 2442 men (69.4%) and 1078 women (30.6%). Males had higher levels of uric acid than women (6.33 ± 1.7 vs 5.8 ± 1.9 - p < 0.001). The association between elevated uric acid (≥7 mg/dl or 0.42 mmol/l) and male gender was confirmed after correction for baseline confounding factors (Adjusted OR = 1.28 [1.01-1.62], p = 0.004). Males displayed a significantly higher prevalence and extent of CAD (p < 0.001) and more complex coronary lesions (p < 0.001). However, no significant relationship was observed between uric acid and CAD (Adjusted OR [95%CI] = 0.90 [0.76-1.06], p = 0.22) or severe CAD (Adjusted OR [95%CI] = 0.89 [0.79-1.01], p = 0.08). Among females, higher SUA levels were significantly associated with higher prevalence of severe CAD (p < 0.001) (Adjusted OR [95% CI] = 1.29 [1.03-1.62], p = 0.03).

CONCLUSION

Our study showed that uric acid levels are significantly higher in men. However, high uric acid levels are associated with severe CAD only in women. Future large studies are certainly needed to confirm our findings and to evaluate the effects of SUA lowering therapies on cardiovascular prevention and outcome, especially in women.

Uric acid promotes chemokine and adhesion molecule production in vascular endothelium via nuclear factor-kappa B signaling

BACKGROUND AND AIMS

Hyperuricemia is an important risk factor for atherosclerosis, yet the potential mechanisms are not well understood. Migration and adhesion of leukocytes to endothelial cells play key roles in initiation and development of atherosclerosis. We investigated monocyte-endothelial cell interactions and potential signaling pathways under uric acid (UA)-stimulated conditions.

METHODS AND RESULTS

Primary human umbilical vein endothelial cells (HUVECs) were cultured and exposed to different concentrations of UA for various periods. Experimental hyperuricemia rat models were established. Expression of chemoattractant protein-1 (MCP-1), interleukin 8 (IL-8), vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) were evaluated. Monocyte-endothelial cell interactions were elucidated by chemotaxis and adhesion assays, and nuclear factor-kappa B (NF-κB) pathway was studied using fluorescent microscopy and electrophoretic mobility shift assay. Results showed that high concentration of UA stimulated generation of chemokines and adhesion molecules in ex vivo and in vivo experiments. Migration and adhesion of human monocytic leukemia cell line THP-1 cells to HUVECs were promoted and activated NF-κB was significantly increased. UA-induced responses were ameliorated by organic anion transporter inhibitor probenecid and NF-κB inhibitor BAY11-7082. It was also observed that human endothelial cells expressed urate transporter-1, which was not regulated by UA.

CONCLUSION

High concentration of UA exerts unfavorable effects directly on vascular endothelium via the NF-κB signaling pathway, the process of which requires intracellular uptake of UA.

Associations of perfluorinated chemical serum concentrations and biomarkers of liver function and uric acid in the US population (NHANES), 2007-2010

BACKGROUND

Perfluorinated chemicals (PFCs) are a group of manmade compounds that are not broken down in the body. Four PFCs (PFHxS, PFOS, PFOA, and PFNA) have been found in the blood of more than 98% of the United States population.

OBJECTIVES

Our goal was to assess associations between PFHxS, PFOS, PFOA, and PFNA and uric acid, alanine transferase (ALT), gamma-glutamyl transferase (GGT), asparate aminotransferase (AST), alkaline phosphate (ALP), and total bilirubin in 2007-2008 and 2009-2010 combined National Health and Nutrition Examination Survey (NHANES).

METHODS

We used multivariate linear regression and logistic regression adjusted for age, gender, race/ethnicity and BMI group, poverty, smoking, and/or alcohol consumption to estimate associations. Trend analysis was performed.

RESULTS

PFHxS was associated with ALT. Each quartile of PFOS was statistically associated with total bilirubin [(Q2: OR=1.44, 95% CI 1.12-1.84), (Q3: OR=1.65, 95% CI 1.25-2.18), and (Q4: OR=1.51, 95% CI 1.06-2.15)], with evidence of an increasing trend (p-value=0.028). PFOA was associated with uric acid, ALT, GGT, and total bilirubin. PFNA was linearly associated with ALT (p-value <0.001), and there was statistically significant increasing trend (p-value=0.042).

CONCLUSIONS

Our analysis found evidence of associations of biomarkers of liver function and uric acid with PFHxS, PFOS, PFOA, and PFNA at levels found in the general U.S. population.

Effect of rosuvastatin on hyperuricemic rats and the protective effect on endothelial dysfunction

Endothelial dysfunction plays a key role in the development of cardiovascular diseases, renal injuries and hypertension induced by hyperuricemia. Therapies targeting uric acid (UA) may be beneficial in cardiovascular diseases. In the present study, the effect of rosuvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, was investigated to determine whether rosuvastatin improves endothelial dysfunction via the endothelial nitric oxide (NO) pathway and delays the pathogenesis of endothelial dysfunction in hyperuricemic rats. A total of 72 Sprague-Dawley rats (age, 8 weeks) were randomly divided into six groups (12 rats per group), including the control, model, 2.5 mg/kg/day rosuvastatin, 5 mg/kg/day rosuvastatin, 10 mg/kg/day rosuvastatin and 53.57 mg/kg/day allopurinol groups. The model, rosuvastatin and allopurinol rats were subjected to hyperuricemia, induced by the administration of yeast extract powder (21 g/kg/day) and oxonic acid potassium salt (200 mg/kg/day). The hyperuricemic rats were treated with 2.5, 5.0 or 10.0 mg/kg/day rosuvastatin orally for six weeks, while rats treated with allopurinol (53.57 mg/kg/day) were used as a positive control. The serum levels of NO and the gene expression levels of endothelial NO synthase in the aortic tissue increased, whereas the serum levels of UA, endothelin-1 and angiotensin II decreased in the hyperuricemic rats treated with rosuvastatin, particularly at a high rosuvastatin dose (10 mg/kg/day). In addition, the curative effect of the 10 mg/kg/day rosuvastatin group was evidently higher compared with the allopurinol group. Therefore, rosuvastatin may be a novel drug candidate for the treatment of hyperuricemia due to its endothelial protective properties.

Screening and characterization of purine nucleoside degrading lactic acid bacteria isolated from Chinese sauerkraut and evaluation of the serum uric acid lowering effect in hyperuricemic rats

Hyperuricemia is well known as the cause of gout. In recent years, it has also been recognized as a risk factor for arteriosclerosis, cerebrovascular and cardiovascular diseases, and nephropathy in diabetic patients. Foods high in purine compounds are more potent in exacerbating hyperuricemia. Therefore, the development of probiotics that efficiently degrade purine compounds is a promising potential therapy for the prevention of hyperuricemia. In this study, fifty-five lactic acid bacteria isolated from Chinese sauerkraut were evaluated for the ability to degrade inosine and guanosine, the two key intermediates in purine metabolism. After a preliminary screening based on HPLC, three candidate strains with the highest nucleoside degrading rates were selected for further characterization. The tested biological characteristics of candidate strains included acid tolerance, bile tolerance, anti-pathogenic bacteria activity, cell adhesion ability, resistance to antibiotics and the ability to produce hydrogen peroxide. Among the selected strains, DM9218 showed the best probiotic potential compared with other strains despite its poor bile resistance. Analysis of 16S rRNA sequences showed that DM9218 has the highest similarity (99%) to Lactobacillus plantarum WCFS1. The acclimated strain DM9218-A showed better resistance to 0.3% bile salt, and its survival in gastrointestinal tract of rats was proven by PCR-DGGE. Furthermore, the effects of DM9218-A in a hyperuricemia rat model were evaluated. The level of serum uric acid in hyperuricemic rat can be efficiently reduced by the intragastric administration of DM9218-A (P<0.05). The preventive treatment of DM9218-A caused a greater reduction in serum uric acid concentration in hyperuricemic rats than the later treatment (P<0.05). Our results suggest that DM9218-A may be a promising candidate as an adjunctive treatment in patients with hyperuricemia during the onset period of disease. DM9218-A also has potential as a probiotic in the prevention of hyperuricemia in the normal population.

Association of serum uric acid and coronary artery disease in premenopausal women

Objective

To date, no study in the published literature has investigated the role of various serum uric acid (SUA) concentrations in the development of angiographically-proven coronary artery disease (CAD) in premenopausal women. Therefore, the aim of this study was to investigate the role SUA levels may play in the prevalence, severity, and prognosis of CAD in premenopausal women.

Methods

This cross-sectional retrospective study included 607 premenopausal women who had undergone coronary angiography. The CAD diagnosis was based upon stenosis affecting ≥50% of the luminal diameter. Association of the SUA levels with CAD prevalence, severity, and clinical outcomes were assessed by statistical analysis.

Results

In total, 369 (60.8%) of the patients were diagnosed with CAD. The CAD patients had significantly higher SUA levels than those without CAD (5.3±1.9 vs. 4.8±1.7 mg/dL, P = 0.001). The SUA levels were found to be significantly associated with CAD prevalence (P = 0.013). Patients with higher levels of SUA also showed increased rates of multivessel disease and composite end-points, such as major adverse cardiac events. Furthermore, multivariate analysis identified abnormally high levels of uric acid (hyperuricemia) as an independent risk factor for CAD (OR 1.51 (1.11–2.53), P<0.05).

Conclusions

The SUA levels are significantly associated with the prevalence of CAD. The SUA levels may be a predictor for incidence of major cardiovascular events in premenopausal women.

Cardiovascular risk factors and total serum antioxidant capacity in healthy men and in men with coronary heart disease

Whether the incidence of coronary heart disease (CHD) is related to a decrease in total antioxidant capacity (TAC) has not yet been completely clarified. We assessed TAC of blood serum in a group of 163 men with CHD aged 34.8–77.0 years and in 163 age-matched peers without CHD. Two spectrophotometric methods were applied to assess TAC: ferric reducing ability of serum (TAC-FRAS) and 2.2-diphenyl-1-picryl-hydrazyl (TAC-DPPH) tests. In the CHD group, multivariate analysis revealed that uric acid (UA), triglycerides, and systolic blood pressure contributed independently to the TAC-FRAS variance. TAC-DPPH was favorably predicted by UA concentration, but negatively so by current smoking and glucose levels. In men without CHD, UA was the only independent determinant of both TAC-FRAS and TAC-DPPH. Presence of CHD was not an independent predictor of TAC—observed between-group differences (higher TAC in CHD patients) disappeared after adjustment for other confounders. We conclude that UA is the main determinant of TAC of blood serum in men. TAC is not directly influenced by age or CHD but is related to several indices of overweight/obesity and laboratory measures of metabolic syndrome, especially in patients with CHD.