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

Genetically predicted type 2 diabetes mellitus mediates the causal association between plasma uric acid and ischemic stroke

OBJECTIVE

This study conducts a systematic investigation into the causal relationships between plasma uric acid levels and subtypes of ischemic stroke (IS), as well as the extent to which Type 2 diabetes mellitus (T2DM) mediates this relationship.

BACKGROUND

There is a known association between Uric acid and IS but whether they have a causal relationship remains unclear. This study aims to determine whether a genetic predisposition to uric acid is causally linked to IS, including three subtypes, and to determine the mediating role of T2DM.

METHODS

Bidirectional Mendelian randomization (MR) analyses was initially used to explore the causal relationship between uric acid and three subtypes of IS. Two-step MR methods were then used to investigate the role of T2DM in mediating the effect of uric acid and IS with its subtypes.

RESULTS

A primary analysis showed uric acid had a markedly causal association with IS (IVW, OR 1.23; 95 % CI, 1.13 - 1.34; p = 6.39 × 10-9), and two subtypes of IS, Large-vessel atherosclerotic stroke LAS (IVW, OR 1.25; 95 % CI, 1.03 - 1.53; p = 0.026) and small vessel stroke (SVS) (IVW, OR 1.20; 95 % CI, 1.00 - 1.43; p = 0.049), but not with cardioembolic stroke (CES)(IVW, OR 1.00; 95 % CI, 0.87 - 1.15; p = 0.993). Two-step MR results showed that T2DM mediated the association between uric acid and LAS and SVS, accounting for 13.85 % (p = 0.025) and 13.57 % (p = 0.028), respectively.

CONCLUSIONS

The study suggests that genetic predisposition to uric acid is linked to a greater risk of IS, especially LAS and SVS. T2DM might mediate a significant proportion of the associations between uric acid and LAS as well as SVS.

Association of Pro-Inflammatory Diet with Long-Term Risk of All-Cause and Cardiovascular Disease Mortality: NIPPON DATA80

AIM

A pro-inflammatory diet may increase the risk of cardiovascular disease (CVD) and all-cause mortality. However, this remains inconclusive as there is yet no study using a dietary record method that has been conducted in a large general population. Furthermore, an underestimation of the pro-inflammatory diet may exist due to the unmeasured effect of salt intake. Thus, in this study, we aimed to examine how pro-inflammatory diet is associated with the long-term risk of all-cause and CVD mortality in a representative Japanese population.

METHODS

A national nutrition survey was conducted throughout Japan in 1980. After considering the exclusion criteria, 9284 individuals (56% women aged 30-92 years) were included in this study. In total, 20 dietary parameters derived from 3-day weighed dietary records were used to calculate the dietary inflammatory index (DII). The causes of death were monitored until 2009. The Cox proportional hazards model was used to determine multivariable-adjusted hazard ratios (HRs). Stratified analysis according to salt intake level was also performed.

RESULTS

Compared with the lowest quartile of DII, multivariable-adjusted HRs (95% confidence intervals) in the highest quartile were 1.28 (1.15, 1.41), 1.35 (1.14, 1.60), 1.48 (1.15, 1.92), 1.62 (1.11, 2.38), and 1.34 (1.03, 1.75) for all-cause mortality, CVD mortality, atherosclerotic CVD mortality, coronary heart disease mortality, and stroke mortality, respectively. Stratified analysis revealed stronger associations among individuals with higher salt intake.

CONCLUSIONS

As per our findings, a pro-inflammatory diet was determined to be positively associated with the long-term risk of all-cause and CVD mortality in a representative Japanese population. Thus, considering both salt intake and pro-inflammatory diet is deemed crucial for a comprehensive assessment of CVD risk.

Uric acid plasma levels are associated with C-reactive protein concentrations and the extent of coronary artery lesions in patients with acute coronary syndromes

Many studies have pointed out that inflammation plays a pivotal role in pathophysiology of acute coronary syndromes (ACS) because several inflammatory molecules impair the endothelial functions in the coronary circulation and promote atherothrombotic events. Recently, many clinical/experimental evidences indicate that elevated plasma levels of uric acid (UA) might be considered a risk factor for developing ACS. It has been reported that elevated UA doses impair physiologic functions of endothelial cells, shifting them toward a pro atherothrombotic phenotype. In the present manuscript, we investigated the relationship between UA plasma levels, inflammatory burden, and extension of coronary atherosclerotic disease in patients with ACS. Patients with a clinical presentation of ACS (ST-elevated and non-ST-elevated myocardial infarction) admitted to the Vanvitelli Catheterization Laboratory at Monaldi Hospital in 2019, before the COVID-19 pandemia, were retrospectively analyzed. Biochemical profile, type of ACS presentation, as well as extension of coronary atherosclerosis were assessed. A total of 132 ACS patients were included in the analysis, and grouped into 3 tertiles according to the UA values (UA < 4.72 mg/dl, UA between 4.72 and 6.15 mg/dl, and UA > 6.15 mg/dl). Patients with UA plasma levels ≥ 6.15 mg/dL showed higher levels of C-reactive protein (mean of 5.1 mg/dL) as compared to patients with lower UA plasma levels. Moreover, the former group of patients showed higher levels of cardiac troponin and CPK, and presented more often with multivessel disease and complex coronary stenosis (type C of Ellis classification). Even though monocentric and with limited sample size, the present study shows that plasma levels of UA and hs-CRP are elevated in ACS patients and are associated with a more severe coronary disease, suggesting a potential role of UA in the pathophysiology of acute coronary events.

Optimal uric acid reduction to improve vascular endothelial function in patients with chronic heart failure complicated by hyperuricemia

Although an association of serum uric acid levels with endothelial function has been shown in various clinical settings, the optimal treatment target that would benefit vascular endothelial function has not been established. We, therefore, conducted a post hoc analysis of the Excited-UA study to identify an optimal target. Patients (N = 133) with chronic heart failure and comorbid hyperuricemia who enrolled in the Excited-UA study were divided into three tertiles based on their serum uric acid level 24 weeks after initiating xanthine oxidase inhibitor treatment with topiroxostat or allopurinol (i.e., groups with low, moderate, and high uric acid levels). Flow-mediated dilation (FMD) and reactive hyperemia index (RHI) values measured by reactive hyperemia peripheral arterial tonometry (RH-PAT) were compared among groups. The change from baseline in the FMD value 24 weeks after treatment was comparable among the three groups. In contrast, the change from baseline in the RHI was significantly different among the three groups (-0.153 ± 0.073, 0.141 ± 0.081 and -0.103 ± 0.104 in the low, moderate, and high uric acid level groups, respectively, P = 0.032). After adjustment for age, body mass index, and concomitant use of diuretics, which differed among the three groups, the change in the RHI in the moderate uric acid level group tended to be higher than that in the high uric acid level group (P = 0.057) and was significantly higher than that in the low uric acid level group (P = 0.020). These results indicate that targeting excessively low uric acid levels by treatment with xanthine oxidase inhibitors might be less beneficial for improving microvascular endothelial function in patients with chronic heart failure. Comparisons of the changes from baseline in vascular endothelial function parameters at 24 weeks among the 3 groups of low, moderae and high uric acid levels achieved with xanthine oxidase inhibitors. After adjustment for confounding factors, such as age, body mass index and concomitant diuretic use, which showed differences among the 3 groups, the change in RHI in the moderate uric acid level group tended to be higher than that in the high uric acid level group and was significantly higher than that in the low uric acid level group.

Asymptomatic Hyperuricemia as an Independent Risk Factor for Myocardial Infarction in Adult Population: A Four-Year Follow-Up Study

Introduction A condition in which uric acid levels are elevated but there are no accompanying symptoms is known as asymptomatic hyperuricemia. As a result of the disparity in opinions and findings between the studies, the guidelines regarding whether or not asymptomatic hyperuricemia should be treated are unclear. Material and methods Between the months of January 2017 and June 2022, this research was carried out in the community in collaboration with the internal medicine unit and the public health unit of Liaquat University of Medical and Health Sciences. After obtaining informed consent from each participant, the researchers enrolled 1,500 patients in the study who had uric acid levels that were greater than 7.0 mg/dL. These patients ranged in age from 40 to 70 years old and were of either gender. As a control group, 1,500 patients were recruited who did not have abnormally high levels of uric acid. Patients were monitored for a total of 48 months or until the occurrence of a major cardiovascular event (MACCE) or death from all causes, whichever occurred first. Death, cardiovascular mortality, non-fatal myocardial infarction, and non-fatal stroke were the four categories that made up the primary outcome, also known as MACCEs. Results In the hyperuricemic group, the incidence of myocardial infarction that did not result in death was significantly higher than in the non-hyperuricemic group (1.6% vs. 0.7%; p-value, 0.04). However, the result was not significant for deaths from all causes, deaths from cardiovascular disease, or strokes that did not result in death. Conclusion Asymptomatic hyperuricemia is a potential threat to one's health that can lead to cardiovascular diseases and may go undiagnosed in some cases. It is important to remember that hyperuricemia can lead to delirious complications, so efforts should be made to perform routine monitoring and management of the condition.

Association of serum uric acid with all-cause and cardiovascular mortality among adults with nonalcoholic fatty liver disease

AIM

The association between serum uric acid (SUA) and mortality from cardiovascular diseases (CVDs) in nonalcoholic fatty liver disease (NAFLD) participants remains uncertain. We aim to investigate the relations of SUA with the risk of CVD mortality among adults with and without NAFLD.

METHODS

Using data from National Health and Nutrition Examination Survey (NHANES) 1999-2014, a total of 17,858 participants were recruited. Of these, 5767 had a US Fatty Liver Index (USFLI) ≥30 and were classified as having NAFLD. Death information was obtained from the National Death Index until 2015.

RESULTS

During a mean follow-up of 8.3 years, 427 participants died from CVD. Overall, there was a positive association between SUA and CVD mortality among participants with NAFLD (per SD μmol/L increment, adjusted hazard ratio [HR], 1.40; 95% confidence interval [CI], 1.16-1.68). Accordingly, among those with NAFLD, when SUA was assessed as quartiles, compared with those in the first quartile, a significantly higher risk of CVD mortality was found in participants in the fourth quartile (adjusted HR, 2.69; 95% CI, 1.51-4.80). However, there was no significant association between SUA and CVD mortality among participants without NAFLD (per SD μmol/L increment, adjusted HR, 1.01; 95% CI, 0.83-1.22). Similar trends were found for all-cause mortality. Similar results were also found when using FLI ≥ 60 to define NAFLD.

CONCLUSIONS

In a large and nationally representative sample of US adults, a higher SUA was significantly associated with a higher risk of CVD mortality among participants with NAFLD, but not in those without NAFLD.

Effect of Chronic Kidney Disease or Anemia or Both on Cardiovascular Mortality in a 25-Year Follow-Up Study of Japanese General Population (From NIPPON DATA90)

The relation between chronic kidney disease (CKD) and cardiovascular disease (CVD) in the general population is well elucidated. In patients with CKD, anemia is associated with adverse outcomes. However, the effects of CKD and anemia on CVD in the general population remains poorly explored, especially in Asian populations. This study aimed to investigate the effect of CKD and/or anemia on CVD mortality in a long-term cohort study involving Japanese community dwellers. We assessed 7,339 participants (aged ≥30 years) with no CVD history. These participants were divided into 4 categories according to their CKD (estimated glomerular filtration rate <60 or urine protein >1+ by dipstick qualitative test) and/or anemia (hemoglobin: <13 g/100 ml [men], <12 g/100 ml [women]) statuses. For each category, we calculated the hazard ratios (HRs) of CVD mortality by using the Cox proportional hazards model after adjusting for age, body mass index, hypertension, diabetes, dyslipidemia, smoking, and alcohol drinking. Within 25 years of follow-up, 637 participants died because of CVD. The HRs of CVD in patients with CKD only, anemia only, and both were 1.27, 1.59, and 2.60 (95% confidence intervals [CI] 1.06 to 1.53, 1.34 to 1.90, and 1.80 to 3.76) in men and 1.42, 1.08, and 2.00 (95% CI 1.19 to 1.69, 0.99 to 1.18, and 1.54 to 2.60) in women, respectively. In conclusion, CKD with anemia is associated with an increased risk for CVD mortality in a general population in Japan.

Effect of changes in serum uric acid on the risk of stroke and its subtypes

BACKGROUND AND AIMS

The role of serum uric acid (SUA) in stroke remains controversial and analyses of changes in SUA and stroke are limited. The objective of the study was to investigate the associations of changes in SUA with stroke and its subtypes (ischemic and hemorrhagic stroke).

METHODS AND RESULTS

A total of 51 441 participants (mean age 52.69 ± 11.71 years) without history of myocardial infarction or stroke were enrolled. Participants were divided into four groups based on SUA level changes during 2006 and 2010: stable low, increasing, decreasing, and stable high. SUA score was quantified on a 3-point scale with 1 point awarded for hyperuricemia at either year 2006, 2008 or 2010. Multivariate Cox proportion models were used to calculated hazard ratios (HRs) and their 95% confidence intervals (CIs). During 7.03-year follow up, 1611 stroke (1410 ischemic stroke, 199 hemorrhagic stroke, and 47 subarachnoid hemorrhage) were identified. Participants with stable high SUA had higher risk of hemorrhagic stroke, the HR was 1.93 (95% CI: 1.06-3.51), compared to those with stable low SUA. Furthermore, cumulative high SUA exposure also increased the risk of hemorrhagic stroke, the HR (95%CI) was 2.99 (1.55-5.74), compared with cumulative low SUA exposure. However, no significant evidence indicated changes in SUA was associated with the risk of total and ischemic stroke, the HRs (95% CIs) were 0.98 (0.74-1.29) and 0.88 (0.65-1.19), respectively.

CONCLUSIONS

Stable high SUA was positively associated with the risk of hemorrhagic stroke, but not with total and ischemic stroke risk.

Increased QT Dispersion and High Risk of Ventricular Arrhythmias is Associated with Hyperuricemia in Individuals with Normal Renal Function

Background and aim: Uric acid elevation has been shown to be an important risk factor for cardiovascular and cerebrobascular disease. QT dispersion (QTd) is a parameter that shows the heterogeneity of ventricular repolarization and can be calculated noninvasively from surface electrocardiography. Increased QTd has been associated with severe arrhythmia and risk of sudden death in many patients and disease groups. In this context, we aimed to investigate the effect of uric acid levels on QTd and the effects of decrease in uric acid levels on QTd.

Methods: A total of 225 patients with normal renal function were included in the study; 133 of these patients were hyperuricemic (>7 mg/dL), and the remaining 72 patients were normouricemic (Group 1). The hyperuricemic patients were randomly divided into 2 groups, one group (n = 67) was given placebo (Group 2) for 4 months, and the remaining 66 patients were given allopurinol 300 mg/day (Group 3).

Results: Hyperuricemic patients had higher hsCRP and QTd and lower eGFR values compared to the normouricemic control group. After 4 months of treatment, 66 patients treated with allopurinol showed a significant decrease in serum uric acid, systolic and diastolic blood pressure, and hsCRP levels, and a significant increase in eGFR. Although the QTd values in the treatment group did not decrease to the same levels as in the normouricemic control group, a statistically significant decrease was found compared to their baseline values. In hyperuricemic control and normouricemic control patients, there were no differences in the levels of uric acid, hsCRP, eGFR, systolic and diastolic blood pressure, and QTd values compared to baseline values.

Conclusions: There was a significant association between elevated serum uric acid and QTd, as well as with inflammatory biomarkers. Also, patients who had received hypouricemic therapy during the follow-up period presented a significant decrease in inflammatory markers as well as QTd. This indicates the beneficial effects of decreasing uric acid levels in decreasing the risk for future major adverse events related to ventricular arrhythmias.

Serum Uric Acid Is a Weak Independent Predictor of Overall Survival in Older Adults

Hyperuricemia accompanies many pathologies that contribute to overall death rate. The population-based multifaceted study of older adults in Poland made it possible to assess the effect of serum uric acid (SUA) on overall mortality. The PolSenior study performed between 2007–2011 included 3926 participants aged 65 years or above (mean age 79 ± 9 years) not treated with xanthin oxidase inhibitors (XOI) who were stratified by sex and SUA concentration into six subgroups increasing by 1 mg/dL. In 2019, survival data were retrieved from the population register. The crude risk of death was significantly higher in men and women with SUA ≥ 7 mg/dL. After adjustment to statistically significant factors, SUA remained a risk factor of death in men with SUA ≥ 8 mg/dL only, potentially due to the limited number of women with high SUA levels. Furthermore, age, heart failure, diabetes, and activities of daily living ≤ 4 pts were identified as factors increasing mortality risk regardless of sex. The risk of death increased also with smoking, past stroke, COPD/asthma, and hs-CRP > 3 mg/dL for men; and eGFR < 45 mL/min/1.73 m², mini nutritional assessment ≤ 7 pts, and loop diuretics use for women. Mild hyperuricemia is a significant health status marker and an independent risk factor for overall mortality in older Caucasians not receiving XOI. Increased mortality is mostly limited to subjects with SUA levels ≥ 8 mg/dL.

The Relationship Between Elevated Serum Uric Acid and Risk of Stroke in Adult: An Updated and Dose-Response Meta-Analysis

Background: Uric acid (UA) is proposed as a potential risk factor for stroke in adult, yet the results from published studies are not generally accordant.

Method: We included prospective studies that explored the relationship between serum UA (SUA) and strokes. In this study, strokes include ischemic stroke and hemorrhagic stroke, which consists of intracerebral hemorrhage and subarachnoid hemorrhage. The effect-size estimates were expressed as hazard ratio (HR) and 95% confidence interval (CI). Sensitivity and subgroup analyses were performed to assess the robustness of the pooled estimation and potential sources of heterogeneity between studies.

Results: We meta-analyzed 19 prospective cohort articles, which involve 37,386 males and 31,163 females. Overall analyses results showed a significant association between a 1 mg/dl increase in high levels of SUA and the risk of total stroke (HR = 1.13; 95% CI: 1.09–1.18; P < 0.001), ischemic stroke (HR = 1.15; 95% CI: 1.10–1.21; P < 0.001), and hemorrhagic stroke (HR = 1.07; 95% CI: 1.00 to 1.15; P = 0.046). No significant difference was found between ischemic stroke and hemorrhagic stroke. In the subgroup analyses, the association of high SUA levels and the risk of total stroke was statistically significant in females (HR = 1.19; 95% CI: 1.12–1.26; P < 0.001) and males (HR = 1.11; 95% CI: 1.05–1.17; P < 0.001). Coincidentally, the association was also statistically significant for ischemic stroke, both in females (HR = 1.26; 95% CI: 1.17–1.36; P < 0.001) and in males (HR = 1.12; 95% CI: 1.06–1.19; P < 0.001). However, for hemorrhagic stroke, it was only statistically significant in females (HR = 1.19; 95% CI: 1.04–1.35; P = 0.01). Our dose–response research indicated the J-shaped trend between the ascending SUA levels and the higher risk of suffering from a stroke.

Conclusions: Our findings indicate that elevated SUA is a significant risk factor for adult stroke, both for ischemic stroke and hemorrhagic stroke, and especially in females.

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.

Serum Uric Acid Levels, but Not rs7442295 Polymorphism of SCL2A9 Gene, Predict Mortality in Clinically Stable Coronary Artery Disease

Serum uric acid (SUA) has been associated with cardiovascular disease, but up to now whether SUA is an independent cardiovascular risk factor or merely a disease-related epiphenomenon remains still controversial. within the framework of the Verona Heart Study, we prospectively followed 703 subjects with angiographically demonstrated and clinically stable coronary artery disease between May 1996 and March 2007. At baseline, SUA levels were measured in all the patients. Genotype data of SCL2A9 rs7442295 polymorphism, which has been associated with SUA by genome-wide association studies, were available for 686 subjects (97.6%). After a median follow-up of 57 months, 116 patients (16.5%) had died, 83 (11.8%) because of cardiovascular causes. Patients with hyperuricemia, defined by SUA levels above the 75th percentile (≥0.41 mmol/L), had an increased total and cardiovascular mortality rate than those with SUA below this threshold level (23.3% vs 14.1%, P = 0.048 and 19.4% vs 9.2%, P = 0.001, respectively, by Kaplan-Meier with Log-Rank test). These associations were confirmed by Cox regression after adjustment for sex, age, other predictors of mortality, coronary revascularization, and drug therapies at discharge (hazard ratio for total mortality 1.87 [1.05-3.34], P = 0.033; hazard ratio for cardiovascular mortality 2.09 [1.03-4.25], P = 0.041). Although associated with SUA levels, rs7442295 polymorphism did not predict total or cardiovascular mortality. our data support that SUA may be a prognostic cardiovascular biomarker, predicting total and cardiovascular mortality in the setting of secondary prevention of coronary artery disease. On the other hand, SCL2A9 gene polymorphism, notwithstanding a clear influence on SUA levels, was not associated with mortality.

Risk Factors That Most Accurately Predict Coronary Artery Disease Based on the Duration of Follow-up - NIPPON DATA80

BACKGROUND

This study assessed sex-specific time-associated changes in the impact of risk factors on coronary artery disease (CAD) mortality in a general population over long-term follow-up.Methods and Results:A prospective longitudinal cohort study was conducted on representative Japanese populations followed up for 29 years. Data from 8,396 participants (3,745 men, 4,651 women) were analyzed. The sex-specific multivariable adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of 4 risk factors (smoking, diabetes, serum total cholesterol [TC], and systolic blood pressure [SBP]) for CAD mortality were calculated at baseline and at 10, 15, 20, 25, and 29 years of follow-up. In men, smoking (HR 3.23; 95% CI 1.16-9.02) and a 1-SD increase in TC (HR 1.82; 95% CI 1.29-2.57) were strongly associated with a higher risk of CAD in the first 10 years, but this association decreased over time. Diabetes (HR 2.30; 95% CI 1.37-3.85) and a 1-SD increase in SBP (HR 1.23; 95% CI 1.00-1.50) were strongly correlated with a higher risk of CAD after 29 years). In women, diabetes was correlated with CAD after 20 years (HR 2.53; 95% CI 1.19-5.36) and this correlation persisted until after 29 years (HR 2.47; 95% CI 1.40-4.35).

CONCLUSIONS

The duration of follow-up needed for the accurate assessment of risk factors for CAD mortality varies according to risk factor and sex.

Serum uric acid and risk of stroke: a dose-response meta-analysis

The relationship between serum uric acid and risk of stroke is still controversial. Therefore, we conducted a meta-analysis based on the cohort study to explore the relationship between serum uric acid and risk of stroke, and further illuminate whether there is a linear or non-linear relationship between them. We manually searched the database including Cochrane, PubMed, Embase, Web of Science, and selected cohort studies focusing on the relationship between serum uric acid and stroke risk. Random effect model was used for statistical analysis. Twenty-one cohort studies involving 818,098 participants were included. The pooled relative risk for the high-vs-low categories was 1.22 (95% CI: 1.15-1.30). In addition, there was a non-linear dose-response relationship between uric acid and stroke risk. Serum uric acid was in the range of 3-5 mg/dl, with the lowest risk of stroke. In conclusion, high serum uric acid level increases the risk of stroke, with a non-linear dose-response relationship.

Association Between Hyperuricemia and Acute Ischemic Stroke in Patients at a Tertiary Care Hospital

Introduction

Stroke is the most debilitating of neurologic diseases. The rationale of the current study was to determine the association between hyperuricemia and ischemic stroke to establish a local perspective.

Methods

A total of 148 patients at a tertiary care hospital in Pakistan who fulfilled the inclusion criteria were enrolled in the study and then equally distributed into two study groups consisting of cases and controls (n = 74 in each group). In this study, there were 36 (48.6%) participants in the case group with hyperuricemia and ischemic stroke and 18 (24.3%) participants in the control group with hyperuricemia. The mean and standard deviations were computed for quantitative variables such as age, body mass index (BMI), and duration of stroke. Frequencies and percentages for the qualitative variables such as gender, hypertension, type 2 diabetes (T2D), dyslipidemia, smoking status, socioeconomic status, educational level, and hyperuricemia were calculated. The chi-square test was applied to compare both groups, with p ≤ 0.05 indicating significance. The odds ratio was also calculated to determine the association between case and control. Effect modifiers were controlled through stratification of age, gender, BMI, duration of stroke, hypertension, T2D, dyslipidemia, socioeconomic status, educational level, and smoking status to determine the effect of these on outcome variables. A post-stratification chi-square test was applied, with p ≤ 0.05 indicating statistical significance.

Results

In our study, stratification of hyperuricemia into cases and controls was performed for age, gender, T2D, hypertension, dyslipidemia, smoking status, socioeconomic status, and educational status. The maximum results were significant, with high strength of association between both groups. In the case group, the frequency of elevated uric acid was significantly higher than that of the control group. A comparison of hyperuricemia indicated p = 0.002, with an odds ratio of 2.95, which showed that elevated uric acid could be taken as a predictor of ischemic stroke. The uric acid level was significantly higher in men than in women. Additionally, hyperuricemia was associated with dyslipidemia. In patients with ischemic stroke, there was a significant association between serum uric acid level and T2D, hypertension, and smoking.

Conclusions

This study showed that the prevalence of hyperuricemia in patients with ischemic stroke was significantly higher as compared to the healthy population. Hyperuricemia can be considered as a risk factor for ischemic stroke because of its high prevalence in ischemic stroke patients. Our study explored the relationship between stroke and hyperuricemia and enabled increased understanding for caregivers so that effective management plans can be formulated for patients with ischemic stroke to prevent adverse outcomes.

Uric acid predicts long-term cardiovascular risk in type 2 diabetes but does not mediate the benefits of fenofibrate: The FIELD study

AIM

To explore the relationship between baseline uric acid (UA) levels and long-term cardiovascular events in adults with type 2 diabetes (T2D) and to determine whether the cardioprotective effects of fenofibrate are partly mediated through its UA-lowering effects.

METHODS

Data from the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial were utilized, comprising 9795 adults with T2D randomly allocated to treatment with fenofibrate or matching placebo. Plasma UA was measured before and after a 6-week, active fenofibrate run-in phase in all participants. Cox proportional hazards models were used to explore the relationships between baseline UA, pre-to-post run-in reductions in UA and long-term cardiovascular outcomes.

RESULTS

Mean baseline plasma UA was 0.33 mmol/L (SD 0.08). Baseline UA was a significant predictor of long-term cardiovascular events, with every 0.1 mmol/L higher UA conferring a 21% increase in event rate (HR 1.21, 95% CI 1.13-1.29, P < .001). This remained significant after adjustment for treatment allocation, cardiovascular risk factors and renal function. The extent of UA reduction during fenofibrate run-in was also a significant predictor of long-term cardiovascular events, with every 0.1 mmol/L greater reduction conferring a 14% lower long-term risk (HR 0.86, 95% CI 0.76-0.97, P = .015). This effect was not modified by treatment allocation (P_interaction = .77).

CONCLUSIONS

UA is a strong independent predictor of long-term cardiovascular risk in adults with T2D. Although greater reduction in UA on fenofibrate is predictive of lower cardiovascular risk, this does not appear to mediate the cardioprotective effects of fenofibrate.

Repeated measurements of serum urate and mortality: a prospective cohort study of 152,358 individuals over 8 years of follow-up

BACKGROUND

Longitudinal evidence on change of serum urate level with mortality risk is limited as prior studies have a measurement of serum urate at a single time point. Further, the combined effect of serum urate and systemic inflammation on mortality is unknown.

METHODS

We conducted a prospective cohort study of 152,358 participants (122,045 men and 30,313 women) with repeated measurements of serum urate in 2006, 2008, 2010, and 2012 (107,751 participants had all four measurements of serum urate). We used the Cox proportional hazard model to examine the association between cumulative average and changes in serum urate with mortality. The combined effect of serum urate and systemic inflammation was determined by testing the interaction of serum urate and high-sensitive C-reactive protein (hs-CRP) in relation to mortality risk.

RESULTS

During a median follow-up of 8.7 (interquartile range 6.3-9.2) years, we identified 7564 all-cause deaths, 1763 CVD deaths, 1706 cancer deaths, and 1572 other deaths. We observed U-shaped relationships of cumulative average serum urate with all-cause mortality, cardiovascular mortality, and other mortalities. Compared with participants with stable serum urate, those with greater increases in serum urate had a 1.7-fold elevated mortality (hazard ratio (HR) = 1.66, 95% confidence interval (CI) = 1.49-1.84), and those with decreased serum urate had a 2-fold elevated mortality risk (HR = 2.14, 95% CI 1.93-2.37). Participants with both hyperuricemia and hs-CRP had 1.6 times higher mortality, compared with those with low serum urate and hs-CRP levels (HR = 1.56, 95% CI 1.37-1.76).

CONCLUSIONS

We observed a U-shaped relationship of long-term cumulative average serum urate with all-cause mortality, cardiovascular mortality, and other mortalities. Compared with participants with relatively stable serum urate levels, a greater increase or decrease in serum urate was associated with elevated mortality. Participants with both hyperuricemia and high systemic inflammation had the greatest mortality risk compared with those with low serum urate and low hs-CRP levels.

The Optimal Range of Serum Uric Acid for Cardiometabolic Diseases: A 5-Year Japanese Cohort Study

The optimal range of serum uric acid (urate) associated with the lowest risk for developing cardiometabolic diseases is unknown in a generally healthy population. This 5-year cohort study is designed to identify the optimal range of serum urate. The data were collected from 13,070 Japanese between ages 30 and 85 at the baseline (2004) from the Center for Preventive Medicine, St. Luke’s International Hospital, Tokyo. We evaluated the number of subjects (and prevalence) of those free of the following conditions: hypertension, diabetes, dyslipidemia, and chronic kidney disease (CKD) over 5 years for each 1 mg/dL of serum urate stratified by sex. Furthermore, the odds ratios (ORs) for remaining free of these conditions were calculated with multiple adjustments. Except for truly hypouricemic subjects, having lower serum urate was an independent factor for predicting the absence of hypertension, dyslipidemia, and CKD, but not diabetes. The OR of each 1 mg/dL serum urate decrease as a protective factor for hypertension, dyslipidemia, and CKD was 1.153 (95% confidence interval, 1.068–1.245), 1.164 (1.077–1.258), and 1.226 (1.152–1.306) in men; 1.306 (1.169–1.459), 1.121 (1.022–1.230), and 1.424 (1.311–1.547) in women, respectively. Moreover, comparing serum urate of 3–5 mg/dL in men and 2–4 mg/dL in women, hypouricemia could be a higher risk for developing hypertension (OR: 4.532; 0.943–21.78) and CKD (OR: 4.052; 1.181–13.90) in women, but not in men. The optimal serum urate range associated with the lowest development of cardiometabolic diseases was less than 5 mg/dL for men and 2–4 mg/dL for women, respectively.

U-shaped association between serum uric acid concentration and mortality in hypertrophic cardiomyopathy patients

Background. No study has examined the effect of low serum uric acid (SUA) concentrations on mortality in hypertrophic cardiomyopathy (HCM) patients. The aim of the present study was to assess the relations between both low and high SUA concentrations and the risk of mortality across the full range of SUA concentrations in a retrospective cohort of HCM patients.Methods. A total of 454 HCM patients were enrolled in the study, and SUA concentrations were measured at baseline. The primary and secondary endpoints were all-cause mortality and HCM-related mortality, respectively. The associations between SUA concentrations and endpoints were analysed.Results. During a median follow-up of 3.8 years, there were 80 (17.6%) all-cause mortality events, and 52 of them (11.5%) were ascribed to HCM-related mortality. Patients with SUA concentrations of 250-350 µmol/L had the lowest all-cause mortality rate (11.8%) and HCM-related mortality rate (5.0%). Both low and high SUA concentrations were associated with increased all-cause and HCM-related mortality. Adjusted HRs were 2.52 (95% CI 1.13-5.61, p = 0.024) and 4.86 (95% CI 1.74-13.58, p = 0.003) for all-cause mortality and HCM-related mortality in the lowest SUA group (<250 µmol/L) when compared with the reference group (250-350 µmol/L), respectively. The corresponding HRs in the highest SUA group (≥450 µmol/L) were 2.73 (95% CI 1.42-5.23, p = 0.003) and 4.14 (95% CI 1.70-10.13, p = 0.002), respectively.Conclusions. Both low and high SUA concentrations were significantly associated with increased risk of all-cause mortality and HCM-related mortality, which supported a U-shaped association between SUA concentrations and mortality in HCM patients.

Soluble Uric Acid Promotes Atherosclerosis via AMPK (AMP-Activated Protein Kinase)-Mediated Inflammation

OBJECTIVE

Uric acid is supposed but not yet determined to be associated with atherosclerosis. Uric acid is released from damaged cells to form urate crystal, which is recognized by the immune system to produce IL (interleukin)-1. Danger signals and IL-1 have been shown to play an important role in atherosclerosis. We determined whether the physiological level of soluble uric acid promotes inflammation and develops atherosclerosis. Approach and Results: The secretion of IL-1β from human peripheral blood mononuclear cells mediated by NLRP3 (NACHT, LRR, and PYD domain-containing protein 3) inflammasome was promoted by physiological levels in serum uric acid. This augmentation of inflammation was mediated by the regulation of the AMPK (AMP-activated protein kinase)-mTOR (mammalian target of rapamycin) mitochondrial reactive oxygen species and HIF-1α (hypoxia-inducible factor-1α) pathway. In both of uricase transgenic and xanthine oxidase inhibitor-treated mice, decreased levels of uric acid resulted in the activation of AMPK and attenuation of the development of atherosclerotic plaques. Further, acute uric acid reduction by the administration of benzbromarone in healthy humans for 2 weeks significantly decreased plasma IL-18-an inflammasome-dependent cytokine.

CONCLUSIONS

The data indicate that the development of atherosclerosis and inflammation is promoted by uric acid in vivo. Moreover, the lowering of uric acid levels attenuated inflammation via the activation of the AMPK pathway. This study provides mechanistic evidence of uric acid-lowering therapies for atherosclerosis.

Association between serum uric acid levels and coronary artery disease in different age and gender: a cross-sectional study

BACKGROUND

The association between uric acid (UA) and coronary artery disease (CAD) was controversial. It was still unclear how the UA level changes with age and gender.

AIMS

To confirm the relationship between the change of UA with age and gender and CAD, especially in elderly people.

METHODS

8285 individuals were investigated. The changes of UA and hyperuricemia in female and male with age were analyzed. The associations of UA, and hyperuricemia with CAD in different age and sex were assessed.

RESULTS

Individuals were stratified into four groups according to their age: ≤ 39 years; 40-59 years; 60-79 years, and ≥ 80 years. The level of UA and the proportion of hyperuricemia increased significantly with age in female (P < 0.001), but showed a downward trend in male (P < 0.001). After adjusting for confounding factors, hyperuricemia remained an independent risk factor for the incident of CAD in all women (P = 0.029). In ≥ 80 year groups of female, UA and hyperuricemia became independent risk factors for the incident of CAD in the univariate and multivariate logistic regression analyses (all P ≤ 0.001).

DISCUSSION

The level of UA showed significantly different changes with age in different gender. The relationship between UA and CAD showed differences in different age and sex.

CONCLUSIONS

There were significant correlations between UA, hyperuricemia, and CAD only in female, particularly in the ≥ 80 year elderly women, but not in men.

Serum Uric Acid - Risk Factor for Acute Ischemic Stroke and Poor Outcomes

Over the last decades several studies among the adult population have attempted to establish a correlation between the risk of stroke incidence and serum uric acid (SUA) concentration, and how these levels influence the patient’s neurological outcome after a stroke. But, to date, the results are conflicting. In this review, an extensive literature search was performed through PubMed for articles published until May 2019 to review the association. The study selection was narrowed by searching PubMed database using the Medical Subject Headings (MesH) and associated keywords. Only articles conducted in English and on human subjects were included. We considered an article for this review if it had statistics on either the incidence, stroke mortality or post-stroke functional outcomes along with serum uric acid levels in adults.

This review includes 21 articles with data of 33,580 cases of stroke and 1,100,888 participants. We can divide the articles reviewed into two separate cohorts of studies. One relates serum uric acid levels to stroke frequency and mortality, while the other is associated with serum uric acid and outcomes for stroke survivors. Based on our review, no significant relationship is observed with uric acid exhibiting protective effects on stroke outcome. Large clinical trials are advised to provide well-defined solutions to further assess the benefits of uric acid level lowering treatment in patients of vascular events, such as a stroke. However, we confidently report that increasing uric acid levels poses a higher risk for incidence of stroke.

Associations of serum uric acid with total and cause-specific mortality: Findings from individuals and pooling prospective studies

BACKGROUND AND AIMS

There is considerable controversy regarding the link between serum uric acid (SUA) and mortality. We prospectively evaluated the association between SUA and risk of total and cause specific (coronary heart disease [CHD], cerebrovascular and cancer) mortality by using the National Health and Nutrition Examination Surveys (NHANES, 1999-2010). Furthermore, a systematic review and meta-analysis of cohort studies was performed to investigate pooled associations of SUA with all-cause and cause-specific mortality.

METHODS

Vital status through December 31, 2011 was ascertained. PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases were searched (up to April 2018). Adjusted Cox proportional hazard regression models were used to determine the association between SUA and mortality. The DerSimonian-Laird method and generic inverse variance methods were used for quantitative data synthesis.

RESULTS

Overall, 21,025 individuals were included (mean age = 47.6 years, 48.7% men) and 3520 deaths occurred during the 144 months of follow-up. In adjusted models, individuals in the highest quartile of SUA had 10 and 8% greater risk of CHD and stroke mortality, whereas there was no link between SUA, all-cause and cancer mortality. The associations of CHD and stroke mortality with SUA were more pronounced in women and, among women, in those aged >50 years. Furthermore, all-cause mortality was positively and significantly related to SUA concentrations only in women. In the meta-analysis, SUA was shown to predict the risk of total (21%), CHD (24%) and stroke (29%) mortality. Furthermore, participants with a higher level of central adiposity had a greater risk of mortality from CHD and stroke for the same level of SUA.

CONCLUSIONS

Our results highlight the adverse impact of SUA on mortality, particularity in older (>50 years) women. The clinical implications of these findings remain to be established in future trials.

Asymptomatic hyperuricemia and incident stroke in elderly Chinese patients without comorbidities

BACKGROUND/OBJECTIVES

Hyperuricemia is usually associated with other comorbidities; so it is difficult to distinguish the effects of hyperuricemia from other coexisting comorbidities in patients who suffer a stroke.

SUBJECT/METHODS

Data for this study were collected from the patients of Kangjian Community Health Center of Shanghai. Selected participants ≥65 years of age were available at enrollment (2009-2013). Subjects were excluded if they had hypertension, diabetes mellitus, pre-existing cardiovascular disease, or hyperlipidemia. Further, patients who were overweight or obese, had gout or drug-treated hyperuricemia, or had chronic kidney disease were also excluded. Cox regression was used in order to assess the hazard ratio (HR) for the incidence of stroke events between hyperuricemic and normouricemic patients.

RESULTS

A total of 3243 subjects without comorbidities (70.8 ± 6.0 years) were followed for 35.5 ± 3.0 months. Hyperuricemia conferred increased cumulative incident stroke events (6.9 versus 3.1%, odds ratio [OR] = 2.27, 95% confidence index [CI] 1.52-3.37, p < 0.001). Male and female hyperuricemic subjects also showed a significantly higher incident stroke incidence than normouricemic subjects (6.1 versus 2.7%, OR = 2.34, 95% CI 1.31-4.18, p = 0.003 and 7.6 versus 3.7%, OR = 2.16, 95% CI 1.25-3.72, p = 0.005, respectively). Cox regression showed that hyperuricemia independently predicted incident stroke risk (HR = 2.32, 95%CI 1.56-3.45).

CONCLUSION

Asymptomatic hyperuricemia carried a significant risk of stroke events in Chinese elderly without comorbidities.

Association of ideal cardiovascular health metrics with serum uric acid, inflammation and atherogenic index of plasma: A population-based survey

BACKGROUND AND AIMS

We aimed to evaluate the link between inflammatory score [consisting of C-reactive protein (CRP) and white blood cells], serum uric acid (SUA) and atherogenic index of plasma (AIP) and the cardiovascular health (CVH) score.

METHODS

We used the cross-sectional National Health and Nutrition Examination Survey database. Statistical analyses accounted for the survey design and sample weights.

RESULTS

Overall, there were 23,004 participants (mean age = 47.2 years, 46.5% males). Participants with an ideal CVH level had the highest ratio of poverty to income (3.62%, p < 0.001), as well as lower levels of CRP, SUA and AIP (p < 0.001 for all comparisons). In adjusted linear regression, a significant negative association was observed between inflammatory score (β = -0.052, p < 0.001), SUA (β = -0.041, p < 0.001) and AIP (β = -0.039, p < 0.001) and CVH score, i.e. participants with a better (greater) CVH score had a lower inflammatory score. Results from adjusted logistic regression showed reduction in the likelihood of "high-risk atherosclerosis" (defined as AIP ≥0.21) [intermediate: odds ratio (OR) = 0.90, 95% confidence interval (CI):0.85-0.95, ideal: OR = 0.81, 95%CI: 0.74-0.88] and "high CVD risk" (defined as CRP ≥3 mg/l) [intermediate: OR = 0.86, 95%CI:0.73-0.98, ideal: OR = 0.82, 95%CI:0.69-0.95] across the categories of CVH.

CONCLUSIONS

Our findings highlight that CVH metrics were associated with inflammatory score, SUA and AIP. Furthermore, participants with a better CVH score had a lower CVD risk. These results reinforce the importance of implementing healthy behaviours as proposed by the American Heart Association. If confirmed in clinical trials, this knowledge may have implications for CVD prevention and management.

Effects of uric acid on vascular endothelial function from bedside to bench

This study was designed to investigate the effects of uric acid on vascular endothelial function in measurements carried out either at the bedside or the laboratory bench. First, we performed reactive hyperemia peripheral arterial tonometry using an EndoPAT 2000 device and measured serum uric acid levels in 92 outpatients with hypertension. The reactive hyperemia index (RHI) showed no correlation with serum uric acid level (R = -0.125, P = 0.235) in either overall patients or in a high-risk group of 51 patients with complications such as cardiovascular and cerebrovascular diseases, chronic kidney disease, and/or diabetes (R = -0.025, P = 0.860). However, in the remaining 41 patients in the low-risk group, RHI correlated negatively with serum uric acid level (R = -0.335, P = 0.032). Multiple regression analysis showed that serum uric acid level predicted RHI (R = -0.321, P = 0.043) in the low-risk group independent of age, body mass index, systolic blood pressure, and low density lipoprotein-cholesterol level. We then performed an in-vitro study using the WST-8 assay in human umbilical vein endothelial cells, which showed that hypoxic conditions reduced cell viability. Treatment with uric acid caused a further reduction in cell viability, while ascorbic acid improved viability. Using Western blot analysis, we observed that uric acid reduced endothelial nitric oxide synthase phosphorylation during hypoxic conditions. Serum uric acid level is associated with peripheral vascular endothelial function in patients with low-risk hypertension and uric acid could directly impair endothelial function under hypoxic conditions. These results are relevant to the interventional studies examining the cardiovascular protective effect of hypouricemic agents.

Is increased uric acid a risk factor or a defensive response? The Campania Salute Network

BACKGROUND AND AIMS

Circulating uric acid (UA) is positively associated with body mass index (BMI), blood glucose, blood pressure (BP), markers of inflammation, and altered lipid profile. UA has also anti-oxidative properties which might be beneficial for cardiovascular (CV) system. It is still debated whether or not UA is independently associated with increased CV morbidity and/or mortality.

METHODS AND RESULTS

We studied prognostic impact of UA in 8833 hypertensive adults (mean age 53 ± 12 yrs, 3857 women) from the Campania Salute Network, without prevalent CV disease and more than stage 3 CKD. We calculated standardized UA Z-score, adjusted for age, sex, glomerular filtration rate, and BMI. Low and high UA and UA Z-score quartiles were compared to the 2 middle quartiles assumed to be "normal". Prevalence of obesity and diabetes was higher in low and high than in normal UA Z-score group (all p < 0.001). Systolic BP, left ventricular mass, carotid intima thickness were significantly higher and ejection fraction was reduced in the presence of high UA Z-score (all p < 0.001). Over 33-months average follow-up, incident major CV end-points (MACE) were not significantly different among low, normal and high UA or UA Z-score. In the latter analysis, however, incident MACE tended to be more frequent in the low than the high UA Z-score. Despite the results of multivariable analyses, the effect of less aggressive therapy in low UA Z-score cannot be excluded with certainty.

CONCLUSION

In treated hypertensive patients, high levels of UA normalized for major biological determinants do not independently predict CV outcome. CLINICALTRIALS.

GOV IDENTIFIER

NCT02211365.

Serum uric acid levels are associated with increased risk of newly developed diabetic retinopathy among Japanese male patients with type 2 diabetes: A prospective cohort study (diabetes distress and care registry at Tenri [DDCRT 13])

OBJECTIVE

We assessed the prospective association between baseline serum uric acid levels and consequent risk of developing diabetic retinopathy.

RESEARCH DESIGN AND METHODS

Data for 1839 type 2 diabetes patients without diabetic retinopathy were obtained from a Japanese diabetes registry. A Cox proportional hazards model with time-varying exposure information by sex was used and adjusted for potential confounders to assess the independent correlations between baseline serum uric acid levels and incidence rate of diabetic retinopathy.

RESULTS

Newly developed diabetic retinopathy was recognized in 188 patients (10.2%) during the observation period of 2 years. Compared to the first serum uric acid quartile level, the multivariate adjusted hazards ratio for diabetic retinopathy development in male patients was 1.97 (95% CI, 1.14-3.41; P = .015), 1.92 (95% CI, 1.18-3.13; P = .008), and 2.17 (95% CI, 1.40-3.37; P = .001) for the second, third, and fourth serum uric acid quartile levels, respectively. But this was not the case with female patients.

CONCLUSION

Higher serum uric acid levels were associated with increased risk of developing diabetic retinopathy in male patients with type 2 diabetes, but not in female patients. Serum uric acid may be a useful biomarker for predicting the future risk of developing diabetic retinopathy in male patients with type 2 diabetes.

Asymptomatic hyperuricemia and coronary artery disease in elderly patients without comorbidities

Because many subjects with hyperuricemia have comorbidities, it can be difficult to differentiate the role of hyperuricemia from that of other comorbidities of coronary artery disease (CAD). Subjects aged ≥ 65 years were enrolled in the study and were available at enrollment and at 5-year follow-up. Subjects were excluded if they were overweight or obese, hypertensive, diabetic, hyperlipidemic, had a pre-existing cardiovascular disease, a history of gout or hyperuricemia on medications, or chronic kidney disease as estimated by a glomerular filtration rate (eGFR) < 60 mL/min per 1.73 m². We used Poisson regression to estimate the hazard ratio (HR) for incident CAD events between hyperuricemic (> 7 mg/dL in men and ≥ 6 mg/dL in women) and normouricemic subjects. A total of 2,142 subjects without comorbidities (mean age of 70.7 ± 5.9 years, 1,194 men) were followed for 57.4 ± 8.9 months. Hyperuricemia was associated with an increased cumulative incidence of incident CAD events (15.0% versus 8.8%, P < 0.001). After adjusting for confounding factors, hyperuricemia independently predicted the risk of incident CAD events (HR=1.71, 95% CI 1.26-2.34). In conclusion, asymptomatic hyperuricemia is a valuable biomarker for predicting the development of incident CAD events.

Fructose Intake, Serum Uric Acid, and Cardiometabolic Disorders: A Critical Review

There is a direct relationship between fructose intake and serum levels of uric acid (UA), which is the final product of purine metabolism. Recent preclinical and clinical evidence suggests that chronic hyperuricemia is an independent risk factor for hypertension, metabolic syndrome, and cardiovascular disease. It is probably also an independent risk factor for chronic kidney disease, Type 2 diabetes, and cognitive decline. These relationships have been observed for high serum UA levels (>5.5 mg/dL in women and >6 mg/dL in men), but also for normal to high serum UA levels (5-6 mg/dL). In this regard, blood UA levels are much higher in industrialized countries than in the rest of the world. Xanthine-oxidase inhibitors can reduce UA and seem to minimize its negative effects on vascular health. Other dietary and pathophysiological factors are also related to UA production. However, the role of fructose-derived UA in the pathogenesis of cardiometabolic disorders has not yet been fully clarified. Here, we critically review recent research on the biochemistry of UA production, the relationship between fructose intake and UA production, and how this relationship is linked to cardiometabolic disorders.

Sex-Specific Relationship Between Serum Uric Acid and Risk of Stroke: A Dose-Response Meta-Analysis of Prospective Studies

Background

Conflicting findings of the association between serum uric acid (UA) and stroke have been reported in both men and women, and it is unclear whether this association was different between men and women. We preformed this meta‐analysis to assess the sex‐specific effect of serum UA on the risk of stroke and its subtypes.

Methods and Results

Prospective studies that reported sex‐specific association of UA levels with stroke or reported in a certain sex were included. Dose‐response relationships were assessed by the generalized least squares trend estimation, and summary effect estimates were evaluated with random‐effect models. Subgroup and sensitivity analyses were performed to assess the potential sources of heterogeneity and the robustness of the pooled estimation. Altogether, 13 prospective studies were identified in this study. The summary of relative risks (95% CIs) of stroke for a 1‐mg/dL increase in serum UA levels were 1.10 (1.05–1.14) for men and 1.11 (1.09–1.13) for women. There is no significant difference in the effect of UA on future stroke risk between men and women (P_interaction=0.736). Subgroup analyses showed that the significant associations persisted in most stratifications, and sensitivity analyses according to various inclusion criteria yielded similar results. A nonlinear relationship was observed in men (P_{non‐linearity}<0.001), with risk increasing significantly from a UA of 6 mg/dL and more steeply at higher UA levels.

Conclusions

Elevated serum UA levels were significantly associated with modestly increased risk of stroke in both men and women and have similar adverse effects on development of stroke in both sexes.

Hyperuricemia and coronary heart disease mortality: a meta-analysis of prospective cohort studies

Background

Hyperuricemia may be associated with an increased risk of coronary heart disease (CHD) mortality; however, the results from prospective studies are conflicting. The objective of this study was to assess the association between hyperuricemia and risk of CHD mortality by performing a meta-analysis.

Methods

Pubmed and Embase were searched for relevant prospective cohort studies published until July 2015. Studies were included only if they reported data on CHD mortality related to hyperuricemia in a general population. The pooled adjusted relative risk (RR) was calculated using a random-effects model.

Results

A total of 14 studies involving 341 389 adults were identified. Hyperuricemia was associated with an increased risk of CHD mortality (RR: 1.14; 95 % CI: 1.06–1.23) and all-cause mortality (RR: 1.20; 95 % CI: 1.13–1.28). For each increase of 1 mg/dl of serum uric acid (SUA), the overall risks of CHD and all-cause mortality increased by 20 and 9 %, respectively. According to the gender subgroup analyses, hyperuricemia increased the risk of CHD mortality in women (RR: 1.47; 95 % CI: 1.21–1.73) compared to men (RR: 1.10; 95 % CI: 1.00–1.19). The risk of all-cause mortality was greater in women.

Conclusions

Hyperuricemia may modestly increase the risk of CHD and all-cause mortality. Future research is needed to determine whether urate–lowering therapy has beneficial effects for reducing CHD mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-016-0379-z) contains supplementary material, which is available to authorized users.

Rationale and design of a multicenter randomized study for evaluating vascular function under uric acid control using the xanthine oxidase inhibitor, febuxostat: the PRIZE study

BACKGROUND

Xanthine oxidase inhibitors are anti-hyperuricemic drugs that decrease serum uric acid levels by inhibiting its synthesis. Xanthine oxidase is also recognized as a pivotal enzyme in the production of oxidative stress. Excess oxidative stress induces endothelial dysfunction and inflammatory reactions in vascular systems, leading to atherosclerosis. Many experimental studies have suggested that xanthine oxidase inhibitors have anti-atherosclerotic effects by decreasing in vitro and in vivo oxidative stress. However, there is only limited evidence on the clinical implications of xanthine oxidase inhibitors on atherosclerotic cardiovascular disease in patients with hyperuricemia. We designed the PRIZE study to evaluate the effects of febuxostat on a surrogate marker of cardiovascular disease risk, ultrasonography-based intima-media thickness of the carotid artery in patients with hyperuricemia.

METHODS

The study is a multicenter, prospective, randomized, open-label and blinded-endpoint evaluation (PROBE) design. A total of 500 patients with asymptomatic hyperuricemia (uric acid >7.0 mg/dL) and carotid intima-media thickness ≥1.1 mm will be randomized centrally to receive either febuxostat (10-60 mg/day) or non-pharmacological treatment. Randomization is carried out using the dynamic allocation method stratified according to age (<65, ≥65 year), gender, presence or absence of diabetes mellitus, serum uric acid (<8.0, ≥8.0 mg/dL), and carotid intima-media thickness (<1.3, ≥1.3 mm). In addition to administering the study drug, we will also direct lifestyle modification in all participants, including advice on control of body weight, sleep, exercise and healthy diet. Carotid intima-media thickness will be evaluated using ultrasonography performed by skilled technicians at a central laboratory. Follow-up will be continued for 24 months. The primary endpoint is percentage change in mean intima-media thickness of the common carotid artery 24 months after baseline, measured by carotid ultrasound imaging.

CONCLUSIONS

PRIZE will be the first study to provide important data on the effects of febuxostat on atherosclerosis in patients with asymptomatic hyperuricemia. Trial Registration Unique trial Number, UMIN000012911 ( https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000015081&language=E ).

Hyperuricemia, Cardiovascular Disease, and Hypertension

In recent years, there has been an increase in the prevalence of hyperuricemia, and the latter has attracted attention as an adult lifestyle-associated disease, together with hypertension, diabetes, and dyslipidemia. Although hyperuricemia is known to be an independent risk factor for hypertension, whether it is an independent risk factor for cardiovascular disease remains controversial. Recently, some small-scale interventional studies on antihyperuricemic medications showed that the latter improved angina symptoms and prevented cardiovascular disease. Here, we will mainly explain the cause of hyperuricemia and the associations between hyperuricemia, hypertension, and cardiovascular disease based on the latest published evidence.

Serum Uric Acid and Mortality Form Cardiovascular Disease: EPOCH-JAPAN Study

AIM

To investigate the relationship between serum uric acid levels and cardiovascular disease in Asians.

METHODS

We examined the above relationship using the data of Evidence for Cardiovascular Prevention from Observational Cohorts in Japan (EPOCH-JAPAN Study). The data of 36,313 subjects (15,628 men and 20,685 women aged 35-89 years without histories of stroke, coronary heart disease, or cancer at baseline) were used for the analyses. Sex-specific hazard ratios (HRs) of mortality from cardiovascular disease were estimated according to the quintiles of serum uric acid using Cox hazard models stratified by cohorts.

RESULTS

During 441,771 person-years of follow-up, we documented 1,288 cardiovascular deaths. A J- or U-shaped relationship between serum uric acid level and cardiovascular disease mortality was observed. Compared with the lowest quintile of serum uric acid levels, the highest quintile was associated with an increased cardiovascular disease mortality in men [HR: 1.28; 95% confidence interval (CI): 1.01-1.63] and women (HR: 1.51; 95% CI: 1.14-1.99). However, there was no significant association with mortality from stroke, coronary heart disease or heart failure in both men and women.

CONCLUSION

This large pooled analysis in Japan suggested a J- or U-shaped relationship between serum uric acid levels and cardiovascular mortality. The highest quintile of serum uric acid levels was associated with increased cardiovascular disease mortality in both Japanese men and women.

Impact of the Serum Uric Acid Level on Subclinical Atherosclerosis in Middle-aged and Elderly Chinese

AIM

The carotid intima-media thickness (CIMT) is now validated as a sensitive marker of atherosclerosis and is directly associated with an increased risk of cardiovascular disease. Considering that the independent association between the serum uric acid level and CIMT remains controversial due to the complex interrelationship with other known cardiovascular risk factors, further studies are needed. The aim of the present study is to explore the association between the serum uric acid level and CIMT in a general Chinese population and determine whether the association differs according to varied metabolic status.

METHODS

The present study was cross-sectional in design. A total of 10,281 community-based participants 40 years of age or older from Shanghai, China were included in the current analysis. All participants underwent a detailed questionnaire interview, anthropometric measurements and ultrasonography to assess the CIMT. Blood and urine samples were collected for the biochemical measurements.

RESULTS

The serum uric acid levels were positively associated with obesity- and diabetes-related parameters and the CIMT. In a logistic regression model controlling for potential confounders, compared with the participants in the first quartile of the uric acid level, those in the fourth quartile had a higher odds of an elevated CIMT in both men (odds ratio [OR]=1.37; 95% confidence interval [CI]=1.07-1.75) and women (OR=1.48; 95% CI=1.12-1.94). The subgroup analyses revealed that an association between an elevated CIMT and the serum uric acid level persisted regardless of diuretic use and the hypertension, diabetes mellitus and chronic kidney disease status. However, the association disappeared in the patients who consumed alcohol and in premenopausal women.

CONCLUSIONS

The serum uric acid level is positively associated with an elevated CIMT in middle-aged and elderly Chinese subjects, independent of known risk determinants of cardiovascular disease.

Effect of serum uric acid on the positive predictive value of dobutamine stress echocardiography

There is controversial data regarding the relationship between uric acid (UA) and coronary artery disease and cardiovascular events. Despite the deleterious effects of hyperuricemia on endothelial function, the effect of UA on myocardial ischemia has not been previously studied. We aimed to investigate the relationship between UA and myocardial ischemia that was identified using dobutamine stress echocardiography (DSE). In this retrospective study, the laboratory and DSE reports of 548 patients were reviewed. The patients were divided into two groups based on the presence of ischemia and further subdivided into three groups according to the extent of ischemia (none, ischemia in 1-3 segments, ischemia in >3 segments). Serum UA levels were compared. Determinants of ischemia were assessed using a regression model. UA was increased in patients with ischemia and was correlated with the number of ischemic segments (p < 0.001). A cutoff value of UA > 5 mg/dl had 63.9 % sensitivity, 62.0 % specificity, 42.5 % positive predictive value (PPV), and 79.6 % negative predictive value for ischemia. When the positive DSE exams were further sorted according to the UA cutoff, the PPV of DSE increased from 80.2 to 94.0 %. Uric acid (odds ratio 1.51; 95 % CI 1.14-1.99), diabetes mellitus, HDL and glomerular filtration rate were found to be independent determinants of myocardial ischemia in DSE. Increased UA is associated with both the presence and extent of DSE-identified myocardial ischemia. A UA cutoff may be a good method to improve the PPV of DSE.

Elevated levels of plasma uric acid and its relation to hypertension in arsenic-endemic human individuals in Bangladesh

Blood uric acid has been recognized as a putative marker for cardiovascular diseases (CVDs). CVDs are the major causes of arsenic-related morbidity and mortality. However, the association of arsenic exposure with plasma uric acid (PUA) levels in relation to CVDs has not yet been explored. This study for the first time demonstrated the associations of arsenic exposure with PUA levels and its relationship with hypertension. A total of 483 subjects, 322 from arsenic-endemic and 161 from non-endemic areas in Bangladesh were recruited as study subjects. Arsenic concentrations in the drinking water, hair and nails of the study subjects were measured by inductively coupled plasma mass spectroscopy. PUA levels were measured using a colorimetric method. We found that PUA levels were significantly (p<0.001) higher in males and females living in arsenic-endemic areas than those in non-endemic area. Arsenic exposure (water, hair and nail arsenic) levels showed significant positive correlations with PUA levels. In multiple regression analyses, arsenic exposure levels were found to be the most significant contributors on PUA levels among the other variables that included age, body mass index, blood urea nitrogen, and smoking. There were dose-response relationships between arsenic exposure and PUA levels. Furthermore, diastolic and systolic blood pressure showed significant positive correlations with PUA levels. Finally, the average PUA levels were significantly higher in the hypertensive group than those in the normotensive group in both males and females living in arsenic-endemic areas. These results suggest that arsenic exposure-related elevation of PUA levels may be implicated in arsenic-induced CVDs.

Modeling effects of SGLT-2 inhibitor dapagliflozin treatment versus standard diabetes therapy on cardiovascular and microvascular outcomes

AIMS

Dapagliflozin, a sodium-glucose cotransporter 2 (SGLT-2) inhibitor, has been shown to lower glycated hemoglobin (HbA1c), weight, blood pressure and serum uric acid in clinical trials. Plasma lipids were also evaluated as exploratory variables. The goal of this study was to estimate the long-term cardiovascular (CV) and microvascular outcomes of dapagliflozin added to the standard of care (SOC) versus SOC using simulation methodology.

METHODS

The Archimedes Model, a validated model of human physiology, diseases and healthcare systems, was used to model a type 2 diabetes mellitus (T2DM) population derived from National Health and Nutrition Examination Survey (NHANES) with HbA1c 7-10%, taking a single oral antidiabetic agent [metformin, sulfonylureas SU or thiazolidinedione (TZD)] at the beginning of the trial. A 20-year trial was simulated comparing dapagliflozin 10 mg, given in addition to SOC, with SOC alone. SOC was based on American Diabetes Association (ADA)/European Association for the Study of Diabetes (EASD) 2012 guidelines and included diet, metformin, SU, TZD, dipeptidyl peptidase-4 (DPP-4), glucagon-like peptide-1 (GLP-1), and insulin therapies, with usage levels reflective of those in NHANES. Dapagliflozin effects were derived from phase 3 clinical trial results. End points included CV and microvascular outcomes.

RESULTS

Over a 20-year period, patients on dapagliflozin were projected to experience relative reductions in the incidence of myocardial infarction (MI), stroke, CV death, and all-cause death of 13.8, 9.1, 9.6 and 5.0%, respectively, and relative reductions in the incidence of end-stage renal disease (ESRD), foot amputation, and diabetic retinopathy of 18.7, 13.0 and 9.8%, respectively, when compared with SOC.

CONCLUSIONS

On the basis of simulation results, adding dapagliflozin to currently available treatment options is projected to further decrease the CV and microvascular complications associated with T2DM.