Elevated serum uric acid and risk of cardiovascular or all-cause mortality in people with suspected or definite coronary artery disease: A meta-analysis

The impact of uric acid on acute coronary syndrome prognosis in elderly patients

BACKGROUND

Uric acid (UA) plays an important role in cardiovascular diseases, yet its implications in elderly patients remains incompletely understood. This study aimed to explore the impact of UA on the prognosis in advanced-age patients with acute coronary syndrome (ACS).

METHODS

We included 526 patients aged 80 and older who were diagnosed with ACS. The UA levels were measured at admission, and patients were divided into four groups based on quartiles of UA levels. Major adverse cardiovascular events (MACE) during follow-up were recorded.

RESULTS

The median UA level was 344.09 μmol/L, while the median follow-up duration was 64 months. Kaplan-Meier curves demonstrated a higher cumulative incidence of MACE during long-term follow-up in the Q4 group (Log-rank p < 0.05). Cox regression analysis revealed an independent correlation between UA levels and an increased risk of MACE (HR 1.002, 95%CI 1.000-1.003, p = 0.021). The ROC curve indicated that the optimal UA value for predicting MACE was 324.25 μmol/L. After matching through PSM, the MACE-free survival rate was lower in both hyperuricemia group (UA> 420.00 μmol/L) and high UA group (324.25 μmol/L < UA≤ 420.00 μmol/L) compared to the control group. Both hyperuricemia and high UA levels were independent risk factors for long-term MACE in advanced-age ACS patients, with HR values of 1.546 (1.049-2.280, p = 0.028) and 1.491 (1.011-2.198, p = 0.044), respectively.

CONCLUSION

Elevated UA levels were identified as independent risk factors for MACE in elderly patients with ACS. The optimal predictive value of UA for poor cardiovascular prognosis was significantly lower than the traditional definition of hyperuricemia.

Cardiovascular Outcomes of Uric Acid Lowering Medications: A Meta-Analysis

BACKGROUND

Although hyperuricemia is a recognized risk factor for cardiovascular diseases, mixed results have been reported regarding the associations between uric acid-lowering medications and cardiovascular events. This meta-analysis compared the cardiovascular outcomes of different uric acid-lowering medications and placebo.

METHODS

Following PRISMA guidelines, we searched OVID Medline, Embase, Web of Science, and Cochrane databases to identify potentially relevant articles until December 2023. Studies must be randomized or observational, report cardiovascular and mortality outcomes, and compare uric acid-lowering medications to placebo or each other. Data was analyzed using Revman (version 5.4) software.

RESULTS

A total of 3,393 studies were searched, after which 47 studies were included, totaling 3,803,509 patients (28 studies comparing xanthine oxidase inhibitors (XOI) versus placebo, 17 studies comparing allopurinol and febuxostat, and 2 studies comparing XOI and uricosuric agents). Overall mean age was 57.3 years, and females comprised 20.8% of all studies. There were no significant differences between XOI and placebo for cardiovascular outcomes (mortality, myocardial infarction, major adverse cardiovascular events, heart failure, or arrhythmia). There was significant heterogeneity in all these pooled analyses. Comparing Allopurinol to Febuxostat, there was a lower risk of heart failure in febuxostat than allopurinol in 3 RCTs (OR 0.66, 95% CI 0.50-0.89, p = 0.006). Other cardiovascular outcomes were not different. Lastly, when comparing XOI and uricosuric agents, no significant differences in MI rates were evident.

CONCLUSION

XOI was not associated with reduced cardiovascular events compared to placebo. When comparing XOI agents, Febuxostat might reduce the risk of HF, but future studies are required to confirm the findings from the current study.

Association of serum uric acid with all-cause and cardiovascular mortality in cardiovascular disease patients

The relationship between serum uric acid (SUA) and mortality in patients with cardiovascular disease (CVD) remains controversial. We aimed to explore the relationship between SUA and all-cause mortality (ACM) and cardiovascular mortality (CVM) in adult patients with CVD. This cohort study included 3977 patients with CVD from the National Health and Nutrition Examination Survey (2005-2018). Death outcomes were determined by linking National Death Index (NDI) records through December 31, 2019. We explored the association of SUA with mortality using weighted Cox proportional hazards regression models, subgroup analysis, Kaplan-Meier survival curves, weighted restricted cubic spline (RCS) models, and weighted threshold effect analysis among patients with CVD. During a median follow-up of 68 months (interquartile range, 34-110 months), 1,360 (34.2%) of the 3,977 patients with cardiovascular disease died, of which 536 (13.5%) died of cardiovascular deaths and 824 (20.7%) died of non-cardiovascular deaths. In a multivariable-adjusted model (Model 3), the risk of ACM (HR 1.38, 95% CI 1.16-1.64) and the risk of CVM (HR 1.39, 95% CI 1.04-1.86) for participants in the SUA Q4 group were significantly higher. In patients with CVD, RCS regression analysis revealed a nonlinear association (p < 0.001 for all nonlinearities) between SUA, ACM, and CVM in the overall population and in men. Subgroup analysis showed a nonlinear association between ACM and CVM with SUA in patients with CVD combined with chronic kidney disease (CKD), with thresholds of 5.49 and 5.64, respectively. Time-dependent ROC curves indicated areas under the curve of 0.61, 0.60, 0.58, and 0.55 for 1-, 3-, 5-, and 10-year survival for ACM and 0.69, 0.61, 0.59, and 0.56 for CVM, respectively. We demonstrate that SUA is an independent prognostic factor for the risk of ACM and CVM in patients with CVD, supporting a U-shaped association between SUA and mortality, with thresholds of 5.49 and 5.64, respectively. In patients with CVD combined with CKD, the association of the ACM and the CVM with SUA remains nonlinear.

Serum uric acid to high-density lipoprotein cholesterol ratio is a predictor for all-cause and cardiovascular disease mortality in patients with diabetes: Evidence from NHANES 2005-2018

BACKGROUND AND AIMS

The relationship between uric acid to high-density lipoprotein cholesterol ratio (UHR) and mortality in individuals with diabetes remains uncertain. This study aimed to explore the relationship between serum UHR and all-cause and cardiovascular disease (CVD) mortality in adults with diabetes.

METHODS AND RESULTS

A total of 5,665 patients with diabetes were enrolled from the 2005-2018 National Health and Nutrition Examination Survey (NHANES). Mortality data were determined through the National Death Index (NDI) until December 31, 2019. The multivariate hazard ratio (HR) and 95% confidence interval (CI) were examined by Cox proportional risk modeling and threshold effects analysis. Stratified analyses were conducted to identify the populations with high-risk mortality. Among the participants with diabetes, 1,088 all-cause mortality, containing 310 CVD mortality occurred. Following adjustment for multivariate, higher UHR was significantly and nonlinearly associated with increased all-cause mortality (HR 1.02, 95% CI 1.02-1.02) and CVD mortality (HR 1.03, 95% CI 1.03-1.03). Furthermore, a U-shaped relationship between UHR and all-cause and CVD mortality, with a plateau at 12.57% for all-cause mortality and 9.86% for CVD mortality. Below the inflection points, a higher UHR was associated with a 4% reduced risk for all-cause mortality. Conversely, exceeding the inflection points, a 4% higher risk for all-cause and a 3% higher risk for CVD mortality associated with elevated UHR.

CONCLUSIONS

Nonlinearity of UHR with all-cause and CVD mortality was observed in adults with diabetes in the United States, with thresholds identified at 12.57% for all-cause and 9.86% for CVD mortality respectively.

The association of perioperative serum uric acid variation with in-hospital adverse outcomes in coronary artery bypass grafting patients

Background

Previous studies proposed the predictive value of baseline serum uric acid (SUA) in the prognosis of coronary artery bypass grafting (CABG) patients. The association of perioperative SUA variation with in-hospital adverse outcomes in CABG patients is unknown.

Methods

A total of 2,453 patients were included in the study and were divided into four groups (G1-G4) according to perioperative SUA variation (ΔSUA) (G1, ΔSUA ≤ -90 μmol/L; G2, -90 μmol/L < ΔSUA < 0; G3, 0 ≤ ΔSUA < 30 μmol/L; G4, 30 μmol/L ≤ ΔSUA.) The basic characteristics and incidence of adverse outcomes were compared between the groups in the overall population and the subgroups. Multivariate logistic regression was performed to explore the association between perioperative SUA increases and adverse outcomes, and receiver operating characteristic analysis was used to obtain the cutoff value of SUA increases.

Results

The patients had a mean age of 60.9 years and the majority were males (76.7%). In the group with the most significant increase in SUA (G4), incidences of in-hospital all-cause death and fatal arrhythmia were higher than in other groups in the overall population and the subgroups. Multivariate logistic regression showed that an increase in the SUA level of ≥30 µmol/L was significantly associated with in-hospital all-cause death and fatal arrhythmia, independent of the baseline SUA level and renal function. This association was significant in most subgroups for in-hospital fatal arrhythmia and in the ≥60 years, myocardial infarction, and female subgroups for in-hospital all-cause death. The cutoff values of SUA increases in the overall population were 54.5 µmol/L for in-hospital all-cause death and 42.6 µmol/L for in-hospital fatal arrhythmia.

Conclusions

The perioperative SUA increase significantly correlated with a higher incidence of in-hospital all-cause death and fatal arrhythmia in CABG patients, independent of the baseline SUA level and renal function. Perioperative SUA variation may provide complementary information in the identification of patients potentially at risk.

A Ten-Year Follow-Up Study of the Association Between Uric Acid and Adverse Cardiovascular Events in Patients With Coronary Artery Disease

The association between uric acid (UA) and long-term mortality in patients with coronary artery disease is poorly investigated. We assessed the association between UA and 10-year mortality after percutaneous coronary intervention (PCI) in 3,998 patients who underwent PCI. Patients were categorized in groups according to UA tertiles: tertile 1 (UA <5.80 mg/100 ml, n = 1,347), tertile 2 (UA 5.80 to 7.04 mg/100 ml, n = 1,340), and tertile 3 (UA >7.94 mg/100 ml, n = 1,311). The primary outcome was 10-year all-cause mortality. All-cause deaths occurred in 1,200 patients: 320 deaths (26.5%) in patients with UA in the first tertile, 325 deaths (26.9%) in patients with UA in the second tertile, and 555 deaths (46.0%) in patients with UA in the third tertile (adjusted hazard ratio 1.22, 95% confidence interval 1.17 to 1.27, p <0.001) for 1 mg/100 ml increment in UA level. Cardiac deaths occurred in 748 patients: 194 deaths (16.5%) in patients with UA in the first tertile, 202 deaths (17.0%) in patients with UA in the second tertile, and 352 deaths (29.7%) in patients with UA in the third tertile (adjusted hazard ratio 1.24 [1.17 to 1.32], p <0.001) for 1 mg/100 ml increment in the UA level. The 10-year rates of target lesion revascularization, target vessel revascularization, or nontarget vessel revascularization did not differ significantly according to the UA level. In conclusion, in patients with coronary artery disease treated with PCI, increased UA level was associated with higher 10-year mortality. Increased UA level was not associated with the progression of atherosclerosis in nontreated coronary vessels or progression of intimal hyperplasia in stented lesions requiring intervention.

Serum uric acid was non-linearly associated with the risk of all-cause and cardiovascular death in individuals with coronary heart disease: a large prospective cohort study

Objective

To investigate the association of serum uric acid (SUA) with all-cause and cardiovascular death in individuals with coronary heart disease (CHD).

Methods

In this prospective cohort study, 1556 individuals from the National Health and Nutrition Examination Survey (1999-2015) were included in the analysis. Multivariate COX regression analysis, restricted cubic spline plot (RCS) and threshold effect were used to investigate the association between SUA and all-cause and cardiovascular death in individuals with CHD.

Results

In the fully adjusted model, when SUA was regarded as a continuous variable, it was closely associated with the risk of all-cause and cardiovascular death (P < 0.01). When all participants were divided into four groups according to the quartile of SUA, compared with Q1 group, only individuals in Q4 group had higher risk of all-cause and cardiovascular death (P = 0.002 and 0.034). The following subgroup analysis showed that the association between SUA and all-cause death risk was still statistically significant in individuals over 60 years old, male, with hypertension, without diabetes and with chronic kidney disease, while the association with cardiovascular death risk only persisted in individuals over 60 years old and male (P < 0.05). Further sensitivity analysis showed that SUA was still closely associated with all-cause and cardiovascular death, whether as a continuous variable or a classified variable (P = 0.007 and 0.044). RCS analysis revealed that SUA had a nonlinear association with all-cause and cardiovascular death risk (P for nonlinearity < 0.01). Threshold effect analysis showed that SUA below 345 umol/L was negatively associated with all-cause and cardiovascular death risk (P < 0.05), while SUA above 345 umol/L was positively associated with all-cause and cardiovascular death risk (P < 0.001), and the 2-piecewise regression model was better than the 1-line regression model (P for likelihood ratio test < 0.05).

Conclusion

SUA had a nonlinear association with all-cause and cardiovascular death risk in individuals with CHD.

Serum uric acid and outcome in hospitalized elderly patients with chronic heart failure through the whole spectrum of ejection fraction phenotypes

INTRODUCTION

Elevated serum uric acid (SUA) levels have been associated with poor outcome in patients with heart failure (HF). Uric acid is associated with inflammation and microvascular dysfunction, which may differentially affect left ventricular ejection fraction (EF) phenotypes. We aimed to identify the role of SUA across EF phenotypes in hospitalized elderly patients with chronic HF.

METHODS

We analyzed 1355 elderly patients who were diagnosed with chronic HF. All patients had SUA levels measured within the first 24 h following admission. Patients with left ventricle EF were categorized as having HF with reduced EF (HFrEF, EF < 40%), HF with mid-range EF (HFmrEF, 40%≦LVEF ≦ 49%) or HF with preserved EF (HFpEF, LVEF ≥ 50%). Endpoints were cardiovascular death, HF rehospitalization, and their composite. The median follow-up period was 18 months.

RESULTS

Compared with the lowest SUA quartile, the highest SUA quartile was significantly associated with the endpoints (adjusted HR: 2.404, 95% CI: 1.178-4.906, P = 0.016; HR: 1.418, 95% CI: 1.021-1.971, P = 0.037; HR: 1.439, 95% CI: 1.049-1.972, P = 0.024, respectively). After model adjustment, a significant association of SUA with cardiovascular death and the composite endpoint persisted among HFrEF and HFmrEF patients in the highest SUA quartile (P < 0.05 for all).

CONCLUSIONS

In hospitalized elderly patients with chronic HF, SUA is an independent predictor of adverse outcomes, which can be seen in HFrEF and HFmrEF patients.

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.

High Uric Acid Promotes Atherosclerotic Plaque Instability by Apoptosis Targeted Autophagy

AIMS

Acute rupture or erosion of unstable atherosclerotic plaques is a major cause of adverse consequences of atherosclerotic cardiovascular disease, often leading to myocardial infarction or stroke. High uric acid (HUA) is associated with the increasing risk of cardiovascular events and death. However, the mechanism by which HUA promotes atherosclerosis and whether HUA affects plaque stability are still unclear.

METHODS

We constructed an atherosclerotic Apoe-/- mouse model with HUA. The progression of atherosclerosis and plaques was determined by Oil Red O staining, hematoxylin and eosin (H&E) staining, and Masson staining. TdT-mediated dUTP nick-end labeling assay and immunohistochemistry were used to observe the changes of apoptosis and autophagy in plaques, respectively. Then, we validated the in vivo results with RAW 264.7 cell line.

RESULTS

HUA promoted atherosclerosis and exacerbated plaque vulnerability, including significantly increased macrophage infiltration, lipid accumulation, enlarged necrotic cores, and decreased collagen fibers. HUA increased cell apoptosis and inhibited autophagy in plaques. In vitro results showed that HUA decreased cell viability and increased cell apoptosis in foam cells macrophages treated with oxidized low-density lipoprotein. An activator of autophagy, rapamycin, can partially reverse the increasing apoptosis.

CONCLUSION

HUA promoted atherosclerosis and exacerbated plaque vulnerability, and HUA facilitates foam cell apoptosis by inhibiting autophagy.

A Systematic Review and Meta-Analysis of the Association between Uric Acid and Allantoin and Rheumatoid Arthritis

Alterations in the circulating concentrations of uric acid and its degradation product, allantoin, might account for the systemic pro-oxidant state and the increased cardiovascular risk in rheumatoid arthritis (RA). We sought to address this issue by conducting a systematic review and meta-analysis of the association between the plasma/serum concentrations of uric acid and allantoin and RA. We searched PubMed, Scopus, and Web of Science from inception to 20 June 2023 for studies comparing plasma/serum concentrations of uric acid and allantoin between RA patients and healthy controls. We assessed the risk of bias with the JBI Critical Appraisal Checklist for analytical studies and the certainty of evidence with the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) Working Group system. In the 19 studies selected for analysis, there were non-significant differences in uric acid concentrations between RA patients and controls (standard mean difference, SMD = 0.11, 95% CI -0.07 to 0.30, p = 0.22; I2 = 87.9%, p < 0.001; low certainty of evidence). By contrast, the concentrations of allantoin were significantly higher in RA patients (SMD = 1.10, 95% CI 0.66 to 1.55, p < 0.001; I2 = 55.6%, p = 0.08; extremely low certainty of evidence). In meta-regression, a significant association was observed between the SMD of uric acid concentrations and body mass index, a risk factor for atherosclerosis and cardiovascular disease (t = 3.35, p = 0.007). Our study has shown a significant increase in the concentrations of the oxidative stress biomarker allantoin in patients with RA. Further research is warranted to investigate the interplay between uric acid, allantoin, redox balance, and cardiovascular disease in this group. (PROSPERO registration number: CRD42023441127).

Hyperuricaemia Does Not Interfere with Aortopathy in a Murine Model of Marfan Syndrome

Redox stress is involved in the aortic aneurysm pathogenesis in Marfan syndrome (MFS). We recently reported that allopurinol, a xanthine oxidoreductase inhibitor, blocked aortopathy in a MFS mouse model acting as an antioxidant without altering uric acid (UA) plasma levels. Hyperuricaemia is ambiguously associated with cardiovascular injuries as UA, having antioxidant or pro-oxidant properties depending on the concentration and accumulation site. We aimed to evaluate whether hyperuricaemia causes harm or relief in MFS aortopathy pathogenesis. Two-month-old male wild-type (WT) and MFS mice (Fbn1^C1041G/+) were injected intraperitoneally for several weeks with potassium oxonate (PO), an inhibitor of uricase (an enzyme that catabolises UA to allantoin). Plasma UA and allantoin levels were measured via several techniques, aortic root diameter and cardiac parameters by ultrasonography, aortic wall structure by histopathology, and pNRF2 and 3-NT levels by immunofluorescence. PO induced a significant increase in UA in blood plasma both in WT and MFS mice, reaching a peak at three and four months of age but decaying at six months. Hyperuricaemic MFS mice showed no change in the characteristic aortic aneurysm progression or aortic wall disarray evidenced by large elastic laminae ruptures. There were no changes in cardiac parameters or the redox stress-induced nuclear translocation of pNRF2 in the aortic tunica media. Altogether, the results suggest that hyperuricaemia interferes neither with aortopathy nor cardiopathy in MFS mice.

Correlation Analysis and Diagnostic Value of Serum Homocysteine, Cystatin C and Uric Acid Levels with the Severity of Coronary Artery Stenosis in Patients with Coronary Heart Disease

Background

Coronary angiography (CAG) is an invasive examination with high risks and costs and various complications may occur. It is necessary to find a diagnostic method, non-invasiveness, inexpensive with low risk. This study aims to analyze the correlation between the levels of serum homocysteine (Hcy), cystatin C (Cys C) and uric acid (UA) and Gensini score in patients with coronary heart disease (CHD) and assess their diagnostic value for CHD.

Methods

A retrospective analysis was conducted on 1412 patients underwent CAG from October 2019 to December 2021, and we conducted this study from January to July 2022. A total of 765 patients with CHD confirmed by CAG were selected as the research group, while 647 patients revealed as non-obstructive stenosis by CAG as the control group. The serum Hcy, Cys C and UA levels were detected and the correlation between Gensini score and variables was analyzed. The receiver-operating characteristic (ROC) curve was performed to assess the diagnostic value of the Hcy, Cys C and UA for CHD.

Results

The serum Hcy, Cys C and UA levels in the research group were higher as compared with the control group (p<0.05). Spearman correlation and multivariate linear regression analysis showed that there was a significantly positive correlation between Gensini score and serum Hcy, Cys C and UA levels (p<0.05). The ROC curve analysis presented the combined Hcy and Cys C with UA having the highest specificity of diagnostic value for CHD (area under the curve (AUC)=0.768, 95% CI 0.706-0.823, specificity = 72.34%, sensitivity = 67.88%, Youden Index = 0.4022).

Conclusion

The serum Hcy, Cys C and UA levels in patients with CHD were significantly increased, positive correlation with Gensini score. The combined Hcy and Cys C with UA could be used to assess the severity of coronary artery stenosis and provide predictive and early intervention treatment values for CHD and a new way of diagnosing CHD, which is cheap, safe, effective and deserving of clinical application.

Concentration of serum uric acid in patients with Renal Artery Stenosis and Hypertension prEdict Future nephropathy and death: C-RASHEF study

Since both serum uric acid (SUA) and renal artery stenosis (RAS) are associated with atherosclerotic events and renal events, it is interesting to investigate whether SUA could predict long-term outcome in patients with RAS. Patients were enrolled from inpatients from 2010 to 2014, must be ≥40-year-old. There were 3269 hypertensive patients enrolled, including 325 RAS patients. Endpoints included all-cause death and new or worsening nephropathy (NNP). In analysis for all-cause mortality, associations between SUA and risk of all-cause mortality were an arising curve in total population, a U-shape curve in non-RAS population, and an arising curve in RAS population. When RAS was involved in multivariate analysis, association between SUA and risk of all-cause mortality was still an arising curve in total population. In analysis for NNP, associations between SUA and risk of NNP were a declining curve in total population, not significant in non-RAS population, and a U-shape curve in RAS population. When RAS was involved in multivariate analysis, association between SUA and risk of NNP in total population was no longer significant. Not only association curve of SUA with mortality in non-RAS patients is different from association curve in RAS patients, but also association curve of SUA with NNP in non-RAS patients is different from association curve in RAS patients. The authors conclude that mechanisms of uric acid for mortality and NNP in RAS patients are different from non-RAS patients. In addition to renal vascular obstruction, uric acid is another significant factor for NNP and death in RAS patients.

Atrial Fibrillation Risk and Urate-Lowering Therapy in Patients with Gout: A Cohort Study Using a Clinical Database

Individuals of Asian descent are at higher risk for developing hyperuricemia and gout as compared to Western populations. Urate-lowering therapy (ULT) is an effective treatment for hyperuricemia and gout. It was reported that febuxostat, one of the ULTs, raises the risk of atrial fibrillation (AF) in elderly populations. Nevertheless, this association has not been properly investigated in Asian populations. We aimed to investigate the development of AF after ULT with different drugs in an Asian population. We conducted a retrospective cohort study using the clinical database at Kaohsiung Veterans General Hospital. Patients newly diagnosed with gout between 1 January 2013 and 31 December 2020 and with a documented baseline serum uric acid (sUA) level but no prior diagnosis of AF were identified. Patients were divided into three groups-allopurinol, benzbromarone, and febuxostat users. During the follow-up period, the risks of incident AF following the initiation of ULT with different drugs were assessed. Development of incident AF was noted in 43 (6%) of the 713 eligible patients during the follow-up period (mean, 49.4 ± 26.6 months). Febuxostat-treated patients had a higher prevalence of certain comorbidities (diabetes mellitus, heart failure, and chronic kidney disease) and higher CHA2DS2-VASc scores. Compared with allopurinol, neither febuxostat nor benzbromarone was associated with increased adjusted hazard ratios (HR) for incident AF (HR: 1.20, 95% confidence interval [CI]: 0.43-3.34; HR: 0.68, 95% CI: 0.22-2.08). There was no difference in the risk of incident AF among Asian patients with gout who received febuxostat, allopurinol, or benzbromarone. Further studies are needed to evaluate long-term cardiovascular outcomes in patients receiving different ULT drugs.

Low serum albumin: A neglected predictor in patients with cardiovascular disease

Albumin, the most abundant circulating protein in blood, is an essential protein which binds and transports various drugs and substances, maintains the oncotic pressure of blood and influences the physiological function of the circulatory system. Albumin also has anti-inflammatory, antioxidant, and antithrombotic properties. Evidence supports albumin's role as a strong predictor of cardiovascular (CV) risk in several patient groups. Its protective role extends to those with coronary artery disease, heart failure, hypertension, atrial fibrillation, peripheral artery disease or ischemic stroke, as well as those undergoing revascularization procedures or with aortic stenosis undergoing transcatheter aortic valve replacement, and patients with congenital heart disease and/or endocarditis. Hypoalbuminemia is a strong prognosticator of increased all-cause and CV mortality according to several cohort studies and meta-analyses in hospitalized and non-hospitalized patients with or without comorbidities. Normalization of albumin levels before discharge lowers mortality risk, compared with hypoalbuminemia before discharge. Modified forms of albumin, such as ischemia modified albumin, also has prognostic value in patients with coronary or peripheral artery disease. When albumin is combined with other risk factors, such as uric acid or C-reactive protein, the prognostic value is enhanced. Although albumin supplementation may be a plausible approach, its efficacy has not been established and in patients with hypoalbuminemia, priority is focused on diagnosing and managing the underlying condition. The CV effects of hypoalbuminemia and relevant issues are considered in this review. Large cohort studies and meta-analyses are tabulated and the physiologic effects of albumin and the deleterious effects of low albumin are pictorially illustrated.

High serum uric acid trajectories are associated with risk of myocardial infarction and all-cause mortality in general Chinese population

Background

Long-term patterns of serum uric acid (SUA) and their association with the risk of myocardial infarction (MI) and mortality are poorly characterized as prior studies measured SUA at a single time point. This study aimed to identify SUA trajectories and determine their associations with incident MI and all-cause mortality.

Methods

We included 85,503 participants who were free of MI in or prior 2012 from the Kailuan study. SUA trajectories during 2006–2012 were identified by group-based trajectory modeling. Cox proportional hazard models were used to assess the association of SUA trajectories with MI and all-cause mortality.

Results

We identified three SUA trajectories during 2006–2012: low-stable (n=44,124, mean SUA: 236–249 μmol/L), moderate-stable (n=34,431, mean SUA: 324–354 μmol/L) and high-stable (n=6,984, mean SUA: 425–463 μmol/L). During a median follow-up of 6.8 years, we documented 817 (0.96%) incident MI and 6498 (7.60%) mortality. Compared with the low-stable group, high-stable group experienced a higher risk of MI (hazard ratio [HR], 1.35; 95% confidence [CI], 1.07–1.71) and all-cause mortality (HR, 1.22; 95% CI, 1.12–1.33). Multiple sensitivity analyses yielded similar results. Additionally, the association of SUA trajectory with MI and all-cause mortality was more pronounced in individuals without a history of hypertension (P-interaction=0.0359) and those aged <60 years (P-interaction<0.0001), respectively.

Conclusions

Higher SUA trajectories were associated with altered risk of MI and all-cause mortality, suggesting that monitoring SUA trajectory may assist in identifying subpopulations at higher risk of MI and all-cause mortality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02812-y.

Are the levels of uric acid associated with biometeorological conditions?

Hyperuricemia is an independent risk factor for renal and cardiovascular diseases and is closely associated with gout episodes. It is caused, inter alia, by nutritional habits and genetic factors, and also displays seasonal variability conditioned by meteorological factors. The impact of meteorological factors, including both cold and heat stress, on the human physiology is presented based on the Universal Thermal Climate Index (UTCI) - a biometeorological index derived from an analysis of human thermal balance. The aim of our study was to establish whether seasonal variations significantly affect routinely measured urine acid (UA) levels and could eventually support the clinical decision making process, as well as assessing whether UTCI values are correlated with UA levels in blood serum. This work presents a retrospective epidemiological study of data collected in Olsztyn (Poland). Study material comprised 54,536 results of ambulatory tests measuring UA levels, performed during the period 2016-2019. The analysis concerned correlations between UA and the ages of female and male subjects as well as existing biometeorological conditions as represented by UTCI values in an annual cycle. UA levels in females were found to be lower (4.94 ± 1.37 SD) as compared to those of males (6.13 ± 1.43 SD) and demonstrated a strong positive correlation with age. UA values differed significantly (p < 0.05) on days characterized by cold stress and heat stress, for the oldest age group. UA levels were found to differ depending on the season, but these relationships were not statistically significant, except for significantly higher UA levels in females in autumn (p < 0.001). However, there was an evident difference in population UA levels under cold stress conditions (lower) and heat stress conditions (higher) in the elderly. The UTCI is an adequate predictor of population variations in UA levels since it takes into account the variability of local meteorological conditions.

High Level of Uric Acid Promotes Atherosclerosis by Targeting NRF2-Mediated Autophagy Dysfunction and Ferroptosis

Atherosclerotic vascular disease (ASVD) is the leading cause of death worldwide. Hyperuricemia is the fourth risk factor for atherosclerosis after hypertension, diabetes, and hyperlipidemia. The mechanism of hyperuricemia affecting the occurrence and development of atherosclerosis has not been fully elucidated. Mononuclear macrophages play critical roles in all stages of atherosclerosis. Studies have confirmed that both hyperuricemia and ferroptosis promote atherosclerosis, but whether high level of uric acid (HUA) promotes atherosclerosis by regulating ferroptosis in macrophages remains unclear. We found that HUA significantly promoted the development of atherosclerotic plaque and downregulated the protein level of the NRF2/SLC7A11/GPX4 signaling pathway in ApoE−/− mice. Next, we evaluated the effect of HUA and ferroptosis inhibitor ferrostatin-1 (Fer-1) treatment on the formation of macrophage-derived foam cells. HUA promoted the formation of foam cells, decreased cell viability, and increased iron accumulation and lipid peroxidation in macrophages treated with oxidized low-density lipoprotein (oxLDL); these effects were reversed by Fer-1 treatment. Mechanistically, HUA significantly inhibited autophagy and the protein level of the NRF2/SLC7A11/GPX4 signaling pathway. Fer-1 activated autophagy and upregulated the level of ferroptosis-associated proteins. Moreover, an NRF2 inducer (tertbutyl hydroquinone (TBHQ)) and autophagy activator (rapamycin (RAPA)) could reverse the inhibitory effect of HUA on foam cell survival. Our results suggest that HUA-induced ferroptosis of macrophages is involved in the formation of atherosclerotic plaques. More importantly, enhancing autophagy and inhibiting ferroptosis by activating NRF2 may alleviate HUA-induced atherosclerosis. These findings might contribute to a deeper understanding of the role of HUA in the pathogenesis of atherosclerosis and provide a therapeutic target for ASVD associated with hyperuricemia.

The Prognostic Impact of Serum Uric Acid on Disease Severity and 5-Year Mortality in Patients With Idiopathic Pulmonary Artery Hypertension

Background

Serum uric acid (UA) has long been identified as a prognostic factor of adverse outcomes in pulmonary hypertension. However, there remains a paucity of evidence on patients with idiopathic pulmonary artery hypertension (IPAH) in the era of targeted drug therapy. This study aims to explore the impact of serum UA levels on the disease severity and mortality in patients with IPAH.

Methods

Consecutive patients diagnosed with IPAH were enrolled, from which UA levels at baseline and the first follow-up were collected. Patients were divided into groups of “hyperuricemia,” which is defined as serum UA level ≥357 μmol/L in women and ≥420 μmol/L in men, and otherwise “normouricemia.” The potential relationship between UA and hemodynamics at right heart catheterization was investigated. Associations between UA and survival were evaluated by Kaplan-Meier analysis and Cox proportional hazard modeling.

Results

Of 207 patients with IPAH, 121 (58.5%) had hyperuricemia. Higher serum UA levels were associated with lower cardiac index (r = 0.47, p < 0.001) and higher pulmonary vascular resistance (r = 0.36, p < 0.001). During a median follow-up of 34 months, there were 32 deaths recorded, accounting for a 15.5% mortality rate. Patients with hyperuricemia had a significantly lower survival rate than those with normouricemia (log-rank test, p = 0.002). Hyperuricemia at baseline was independently associated with a 2.6-fold increased risk of 5-year death, which was consistent across different subgroups, especially in females and those aged ≥30 years (each p < 0.05). Individuals with higher variability in UA had a higher mortality than those with stable UA (log-rank test, p = 0.024).

Conclusions

Baseline hyperuricemia and high variability in serum UA at first follow-up were related to a higher rate of 5-year mortality in patients with IPAH. Closely detecting the UA levels may aid in the early recognition of IPAH patients at higher mortality risk.

Prognostic Significance of Uric Acid in Patients with Obstructive and Nonobstructive Coronary Artery Disease Undergoing D-SPECT

Purpose

The association of serum uric acid (SUA) levels with cardiovascular outcomes in patients with coronary artery disease (CAD) has been extensively studied and yielded conflicting results. We aimed to investigate whether the severity of coronary stenosis and ischemia influences the prognostic impact of SUA levels in patients with CAD undergoing D-SPECT.

Patients and Methods

This study consecutively included patients who were admitted for CAD in Shanghai Tenth People's Hospital between June 2014 and August 2018, had complete SUA data and underwent both coronary angiography and D-SPECT within 3 months. Hyperuricemia was defined as an SUA level of >7 mg/dL in men and >6 mg/dL in women. The primary outcome was major adverse cardiovascular events (MACE), defined as a composite of cardiac death, unplanned coronary revascularization, nonfatal myocardial infarction, ischemic stroke, heart failure, and angina-related hospitalization.

Results

A total of 695 patients were included, of whom 432 (62.2%) presented with obstructive CAD and 117 (16.8%) had hyperuricemia. During a median follow-up of 26 months, the incidence rates of MACE in patients with hyperuricemia and normouricemia were 15.2% and 21.1%, respectively. After a multivariable adjustment, hyperuricemia was significantly associated with an increased risk of MACE (HR: 1.39, 95% CI: 1.03-1.87, p = 0.033) when compared with normouricemia. When repeating the primary analysis in patients with and without obstructive CAD, we showed that hyperuricemia was independently associated with an 80% increased risk of MACE among patients with nonobstructive CAD (HR: 1.80, 95% CI: 1.04-3.11, p = 0.035), while such a significant association was not found among those with obstructive CAD (HR: 1.18, 95% CI: 0.82-1.72, p = 0.373). Moreover, we uncovered a U-shaped and linear trajectory of SUA levels with MACE in the obstructive and nonobstructive CAD, respectively. The sex-specific analysis showed that the adverse impact of hyperuricemia was only pronounced in males (HR: 1.73, 95% CI: 1.18-2.53, p = 0.005) but not in females (HR: 0.98, 95% CI: 0.57-1.66, p = 0.933).

Conclusion

Hyperuricemia is significantly associated with increased risk of MACE in the nonobstructive CAD rather than in the obstructive CAD.

Relationship between serum uric acid, all-cause mortality and cardiovascular mortality in peritoneal dialysis patients: systematic review and meta-analysis of cohort studies

OBJECTIVES

To analyse the relationship between serum uric acid (SUA), all-cause and cardiovascular (CV) mortality in peritoneal dialysis (PD) patients to inform clinical practice and future research.

DESIGN

A systematic review of observational studies.

DATA SOURCES

PubMed, Embase, Web of Science, the Cochrane Library, China National Knowledge Infrastructure (CNKI), SinoMed, Chinese Science and Technology Journal Database (VIP) and Wan Fang databases were searched from their inception to January 2021 for cohort and case-control studies reporting SUA and mortality in patients with PD.

METHODS

The Newcastle-Ottawa Quality Assessment Scale was used to appraise quality of cohort and case-control studies. Effect estimates were presented as HRs with 95% CIs in a meta-analysis using STATA V.16.0. Data not suitable for pooling were synthesised qualitatively.

RESULTS

Fourteen cohort studies with 24 022 patients were included. No case-control studies were identified. For prospective cohort studies, pooled results for the highest SUA category were significantly greater than the lowest for all-cause (one study; 1278participants; HR 1.79; 95% CI 1.17 to 2.75) and CV mortality (one study; 1278 participants; HR 2.63; 1.62-4.27). An increase of 1 mg/dL in SUA level was associated with a 16% increased risk of all-cause mortality (one study; 1278 participants; HR 1.16; 1.03-1.32) and 34% increased CV mortality risk (one study; 1278 participants; HR 1.34; 1.16-1.55). For retrospective cohort studies, the highest SUA category did not demonstrate an elevated all-cause (five studies; 4570 participants; HR 1.09; 0.70-1.70) or CV mortality (three studies; 3748 participants; HR 1.00; 0.44-2.31) compared with the lowest SUA category. Additionally, there was no increase in all-cause (eight studies; 11 541 participants; HR 0.94; 0.88-1.02) or CV mortality (three studies; 7427 participants; HR 0.90; 0.76-1.06) for every 1 mg/dL increase in SUA level.

CONCLUSIONS

Results of prospective and retrospective cohort studies were inconsistent. Consequently, prospective, multicentre, long-term follow-up studies are required to confirm the relationship between SUA and mortality in patients with PD.

Evaluation of the prognostic ability of serum uric acid for elderly acute coronary syndrome patients with diabetes mellitus: a prospective cohort study

OBJECTIVES

This study evaluated the prognostic power of serum uric acid (UA) in predicting adverse events in elderly acute coronary syndrome (ACS) patients with diabetes mellitus (DM).

METHODS

The analysis involved 718 ACS patients ‍>80 years old whose general clinical data and baseline blood biochemical indicators were collected prospectively from January 2006 to December 2012. These patients were classified into two groups based on DM status, and then followed up after discharge. The Kaplan-Meier method was used for major adverse cardiac event (MACE) rates and all-cause mortality. Multivariate Cox regression was performed to analyze the relationship between UA level and long-term clinical prognosis. Receiver operating characteristic (ROC) curves were analyzed to predict the cutoff value of UA in elderly ACS patients with DM. There were 242 and 476 patients in the DM and non-DM (NDM) groups, respectively, and the follow-up time after discharge was 40‒120 months (median, 63 months; interquartile range, 51‒74 months).

RESULTS

The all-cause mortality, cardiac mortality, and MACE rates in both DM and NDM patients were higher than those in the control group (P=0.001). All-cause mortalities, cardiac mortalities, and MACE rates in DM patients with moderate and high UA levels were significantly higher than those in the NDM group (P=0.001). Long-term survival rates decreased significantly with increased UA levels in the ACS groups (P=0.001). UA (odds ratio (OR)=2.106, 95% confidence interval (CI)=1.244‒3.568, P=0.006) was found to be an independent risk factor for all-cause mortality and MACE in elderly ACS patients with DM. The cutoff value of UA was 353.6 μmol/L (sensitivity, 67.4%; specificity, 65.7%).

CONCLUSIONS

Serum UA level is a strong independent predictor of long-term all-cause death and MACE in elderly ACS patients with DM.

The Impact of Uric Acid and Hyperuricemia on Cardiovascular and Renal Systems

The description of gout dates back almost 5000 years, and scientific interest in uric acid increased when it was found to be involved in the pathogenesis of gout. Since then, many basic and clinical studies have assessed the implications of uric acid for the oxidative system, inflammation, and cardiovascular and renal outcomes. Uric acid-lowering therapy failed to improve clinical hard outcomes in asymptomatic hyperuricemia, and it is retained in symptomatic hyperuricemia. Dietary and lifestyle modifications are critical to manage hyperuricemia. More studies are warranted to investigate the role of uric acid-lowering drugs on cardiovascular outcomes.

Hyperuricemia-induced endothelial insulin resistance: the nitric oxide connection

Hyperuricemia, defined as elevated serum concentrations of uric acid (UA) above 416 µmol L^-1, is related to the development of cardiometabolic disorders, probably via induction of endothelial dysfunction. Hyperuricemia causes endothelial dysfunction via induction of cell apoptosis, oxidative stress, and inflammation; however, it's interfering with insulin signaling and decreased endothelial nitric oxide (NO) availability, resulting in the development of endothelial insulin resistance, which seems to be a major underlying mechanism for hyperuricemia-induced endothelial dysfunction. Here, we elaborate on how hyperuricemia induces endothelial insulin resistance through the disruption of insulin-stimulated endothelial NO synthesis. High UA concentrations decrease insulin-induced NO synthesis within the endothelial cells by interfering with insulin signaling at either the receptor or post-receptor levels (i.e., proximal and distal steps). At the proximal post-receptor level, UA impairs the function of the insulin receptor substrate (IRS) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) in the insulin signaling pathway. At the distal level, high UA concentrations impair endothelial NO synthase (eNOS)-NO system by decreasing eNOS expression and activity as well as by direct inactivation of NO. Clinically, UA-induced endothelial insulin resistance is translated into impaired endothelial function, impaired NO-dependent vasodilation, and the development of systemic insulin resistance. UA-lowering drugs may improve endothelial function in subjects with hyperuricemia.

The prognosis and risk factors of baseline high peritoneal transporters on patients with peritoneal dialysis

The relationship between baseline high peritoneal solute transport rate (PSTR) and the prognosis of peritoneal dialysis (PD) patients remains unclear. The present study combined clinical data and basic experiments to investigate the impact of baseline PSTR and the underlying molecular mechanisms. A total of 204 incident CAPD patients from four PD centres in Shanghai between 1 January 2014 and 30 September 2020 were grouped based on a peritoneal equilibration test after the first month of dialysis. Analysed with multivariate Cox and logistic regression models, baseline high PSTR was a significant risk factor for technique failure (AHR 5.70; 95% CI 1.581 to 20.548 p = 0.008). Baseline hyperuricemia was an independent predictor of mortality (AHR 1.006 95%CI 1.003 to 1.008, p < 0.001) and baseline high PSTR (AOR 1.007; 95%CI 1.003 to 1.012; p = 0.020). Since uric acid was closely related to high PSTR and adverse prognosis, the in vitro experiments were performed to explore the underlying mechanisms of which uric acid affected peritoneum. We found hyperuricemia induced epithelial‐to‐mesenchymal transition (EMT) of cultured human peritoneal mesothelial cells by activating TGF‐β1/Smad3 signalling pathway and nuclear transcription factors. Conclusively, high baseline PSTR induced by hyperuricaemia through EMT was an important reason of poor outcomes in CAPD patients.

Serum Uric Acid Revealed a U-Shaped Relationship With All-Cause Mortality and Cardiovascular Mortality in High Atherosclerosis Risk Patients: The ASSURE Study

Background: Previous studies have demonstrated an association between hyperuricemia and cardiovascular disease (CVD). The Framingham study confirmed that patients with high atherosclerotic risks (HARs) had worse prognoses. However, after adjusting for confounding factors, the association between serum uric acid (SUA) and all-cause mortality and cardiovascular mortality remains unclear, especially for HAR patients. Objective: The aim of this study was to reveal the relationship of SUA with all-cause and cardiovascular mortality in HAR patients. Methods: This multicenter cohort study enrolled 3,047 participants, and the follow-up was 68.85 ± 11.37 months. Factors related to cardiovascular and all-cause mortality were tested by multivariate Cox regression analysis. Restricted cubic splines (RCSs) with knots were used to explore the shape of the dose-response relationship with SUA and the hazard ratio (HR) of all-cause and CVD mortality. SUA transformed by RCS was added to the Cox regression model as an independent variable, and all-cause and CVD mortality scores were calculated. Survival receiver operating characteristic curves were produced using a regression model predicting the score. Results: SUA demonstrated a "U-shaped" relationship with all-cause and cardiovascular mortality. SUA predicted all-cause and CVD mortality, with cutoff values of values of >370.5 μmol/L for males and >327.65 μmol/L for females and <180.5 μmol/L for males and <165.7 μmol/L for females, respectively. The survival ROC curve indicated that SUA is able to predict all-cause and CVD mortality, with areas under the curve of 0.702 and 0.711, respectively. The HRs of all-cause mortality (male and female) with hyperuricemia and hypouricemia were 2.08 and 2.01 and 2.04 and 1.98, respectively, and the HRs of CVD mortality (male and female) were 2.09 and 1.79, and 2.02 and 1.89, respectively. Conclusion: Abnormal SUA levels were significant and independent risk factors for all-cause and CVD mortality. Hyperuricemia and hypouricemia increased mortality in both males and females. Routine SUA evaluation and intensive management are needed for HAR patients. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT03616769.

Association of serum uric acid with mortality and cardiovascular outcomes in patients with hypertension: a meta-analysis

Studies on the association of uric acid with mortality and cardiovascular outcomes in patients with hypertension have produced contradictory results. The objective of this meta-analysis was to evaluate the prognostic utility of uric acid in hypertensive patients. We comprehensively searched PubMed and Embase databases (until July 31, 2020) to identify eligible studies that reported the association of uric acid with mortality and cardiovascular outcomes in hypertensive patients. Outcome measures included cardiovascular or all-cause mortality, coronary artery disease (CAD), stroke, and major adverse cardiovascular events (MACEs). Eleven eligible studies of 49,800 hypertensive patients were identified. For patients with the highest than those with reference lower group of uric acid level, the pooled hazard ratio (HR) was 1.51 (95% confidence interval [CI] 1.12-2.02) for all-cause mortality, 1.68 (95% CI 1.28-2.20) for cardiovascular mortality, 1.31 (95% CI 1.10-1.55) for CAD, and 1.48 (95% CI 1.28-1.70) for MACEs. However, there was no significant association between elevated uric acid level and incident stroke in hypertensive patients. This meta-analysis indicates that elevated uric acid level is significantly associated with an increased risk of cardiovascular or all-cause mortality, CAD and MACEs in hypertensive patients. Hypertensive patients with highest uric acid level exhibited a tendency for reduced risk of stroke, but the difference is not significant.

Hepatic Accumulation of Hypoxanthine: A Link Between Hyperuricemia and Nonalcoholic Fatty Liver Disease

BACKGROUND

An elevated level of plasma uric acid has been widely recognized as a risk factor for non-alcoholic fatty liver disease (NAFLD), where oxidative stress and inflammation play an important role in the pathophysiology of the disease. Although the complete molecular mechanisms involved remain unknown, while under physiological conditions uric acid presents antioxidant properties, hyperuricemia has been linked to oxidative stress, chronic low-grade inflammation, and insulin resistance, basic signs of NAFLD.

AIM OF STUDY

Employing in vivo experimentation, we aim to investigate whether a high-fat diet rich in cholesterol (HFD), modifies the metabolism of purines in close relationship to molecular events associated with the development of NAFLD. In vitro experiments employing HepG2 cells are also carried out to study the phenomenon of oxidative stress.

METHODS

Adult male rabbits were fed for 8 weeks an HFD to induce NAFLD. At the beginning of the experiment and every 15 d until the completion of the study, plasma levels of lipids, lipoproteins, and uric acid were measured. Liver tissue was isolated, and histology performed followed by the biochemical determination of hypoxanthine, protein expression of xanthine oxidoreductase (XOR) by western blot analysis, and xanthine oxidase (XO) activity using an enzymatic kinetic assay. Furthermore, we employed in vitro experimentation studying HepG2 cells to measure the effect of hypoxanthine and H₂O₂ upon the production of radical oxygen species (ROS), XO activity, and cell viability.

RESULTS AND CONCLUSION

Hepatic tissue from rabbits fed the HFD diet showed signs of NAFLD associated with an increased ROS concentration and an altered purine metabolism characterized by the increase in hypoxanthine, together with an apparent equilibrium displacement of XOR towards the xanthine dehydrogenase (XDH) isoform of the enzyme. This protein shift visualized by a western blot analysis, associated with an increase in plasma uric acid and hepatocyte hypoxanthine could be understood as a compensatory series of events secondary to the establishment of oxidative stress associated with the chronic establishment of fatty liver disease.

Changes in serum uric acid and the risk of cardiovascular disease and all-cause mortality in the general population

BACKGROUND AND AIM

Longitudinal evidence on change in serum (SUA) with risk of cardiovascular disease (CVD) and all-cause mortality is limited, as many prior studies focused on baseline SUA. Further, the optimal threshold range of SUA change is unclear.

METHODS AND RESULTS

A total of 63,127 participants without history of CVD were enrolled. Change in SUA was determined by the difference of SUA levels between 2006 and 2010, which divided by baseline SUA was percent change in SUA. Multivariable Cox proportional hazards models were used to calculated the hazard ratios (HRs) and 95% confidence intervals (CIs). Our analysis also included restricted cubic spline model and three-piecewise Cox proportion hazards model to address the non-linearity between percent change in SUA and outcomes. During a median follow-up of 7.04 years, 3341 CVD and 3238 deaths occurred. We did not observed a significant association between changes in SUA and CVD. However, changes in SUA at extreme were associated with higher risk of all-cause mortality, the HRs (95% CIs) were 1.15 (1.02-1.29) and 1.20 (1.06-1.35) in the first and fifth quintile group, compared with the third quintile group. We further found a U-shaped association between percent change in SUA and all-cause mortality, and the optimal range was within 20%.

CONCLUSIONS

Changes in SUA at extreme were risk factors for all-cause mortality, but not for CVD in the general population. The findings are relevant for role of SUA in the management of CVD risk and may contribute to improve identification of patients at higher risk.

Visit-to-visit variability of serum uric acid measurements and the risk of all-cause mortality in the general population

Background

Evidence on longitudinal variability of serum uric acid (SUA) and risk of all-cause mortality in the general population is limited, as many prior studies focused on a single measurement of SUA.

Methods

A total of 53,956 participants in the Kailuan study who underwent three health examinations during 2006 to 2010 were enrolled. Variability of SUA was measured using the coefficient of variation (primary index), standard deviation, average real variability, and variability independent of the mean. Cox proportional hazard regressions were used to calculate the hazard ratio (HR) and 95% confidence interval (CI) for the association of variability of SUA with subsequent risk of all-cause mortality, considering its magnitude and the direction and across different baseline SUA categories.

Results

Over a median follow-up of 7.04 years, 2728 participants died. The highest variability of SUA was associated with an increased risk of all-cause mortality, the HR was 1.33 (95% CI, 1.20–1.49) compared with the lowest variability. In this group, both a large fall (HR, 1.28; 95% CI, 1.14–1.44) and rise (HR, 1.18; 95% 1.05–1.32) in SUA were related to risk of all-cause mortality. These associations were similar across different baseline SUA categories. Consistent results were observed in alternative measures of SUA variability. Moreover, individuals with higher variability in SUA were more related to common risk factors than those with stable SUA.

Conclusions

Higher variability in SUA was independently associated with the risk of all-cause mortality irrespective of baseline SUA and direction of variability in the general population.

Uric acid to high-density lipoprotein cholesterol ratio predicts cardiovascular mortality in patients on peritoneal dialysis

BACKGROUND AND AIMS

Serum uric acid (UA) and high-density lipoprotein cholesterol (HDL-C) disorders are both considered as risk factors of cardiovascular mortality. The predictive value of UA to HDL-C ratio (UHR) has been validated in diabetes. However, association of UHR with cardiovascular (CV) mortality is undetermined in peritoneal dialysis (PD) patients.

METHODS AND RESULTS

In this retrospective cohort study, we enrolled 1953 eligible incident patients who commenced PD treatment on our hospital from January 1, 2006 to December 31, 2015, and followed up until December 31, 2019. Of the participants, 14.9% were older than 65 years (mean age 47.3 ± 15.2 years), 24.6% were diabetics, and 59.4% were male. Patients were categorized into quartiles according to baseline UHR level. Multivariate Cox Proportional Regression analysis was applied to explore the association of UHR with mortality. Overall, 567 patients died during a median follow-up period of 61.3 months, of which 274 (48.3%) were attributed to CV death. The mean baseline UHR was 16.4 ± 6.7%. Compared to quartile 2 UHR, hazard ratios (HRs) for the highest quartile UHR were 1.35 (95% confidence interval [CI] 1.06-1.78; P = 0.017) and 1.46 (95% CI 1.00-2.12; P = 0.047) for all-cause and CV mortality, respectively. Subgroup analysis showed that association of UHR with CV mortality was remarkable among PD patients with age ≥65 years, malnutrition (albumin <35 g/L), diabetes, and CVD history.

CONCLUSIONS

An elevated UHR predicted increased risk of all-cause and CV mortality in PD patients.

Hyperuricemia as a Risk Factor for Cardiovascular Diseases

Serum uric acid level above 7 mg/dl is defined as hyperuricemia, which gives rise to the monosodium urate (MSU), causing gout and urolithiasis. Hyperuricemia is an independent risk factor as well as a marker for hypertension, heart failure, atherosclerosis, atrial fibrillation, and chronic kidney disease. MSU crystals, soluble uric acid (UA), or oxidative stress derived from xanthine oxidoreductase (XOR) might be plausible explanations for the association of cardio-renovascular diseases with hyperuricemia. In macrophages, MSU activates the Nod-like receptor family, pyrin　domain containing 3(NLRP3) inflammasome, and proteolytic processing mediated by caspase-1 with enhanced interleukin (IL)-1β and IL-18 secretion. Soluble UA accumulates intracellularly through UA transporters (UAT) in vascular and atrial myocytes, causing endothelial dysfunction ad atrial electrical remodeling. XOR generates reactive oxygen species (ROS) that lead to cardiovascular diseases. Since it remains unclear whether asymptomatic hyperuricemia could be a risk factor for cardiovascular and kidney diseases, European and American guidelines do not recommend pharmacological treatment for asymptomatic patients with cardio-renovascular diseases. The Japanese guideline, on the contrary, recommends pharmacological treatment for hyperuricemia with CKD to protect renal function, and it attaches importance of the cardio-renal interaction for the treatment of asymptomatic hyperuricemia patients with hypertension and heart failure.

Impact of uric acid on immature platelet fraction in patients undergoing percutaneous coronary intervention

INTRODUCTION

Reticulated platelets have been involved in the pathophysiology of coronary artery disease (CAD). Immature platelet fraction (IPF) allows their measurement in daily clinical practice, although the factors conditioning their elevation are still largely unexplored. Serum uric acid (SUA) is the end product of purine metabolism, displaying a pro-oxidant and pro-inflammatory action and increasing the cardiovascular risk. The aim of our study was to investigate the impact of SUA on IPF levels in patients undergoing percutaneous coronary intervention (PCI), and their relationship with CAD.

METHODS

We enrolled a cohort of consecutive patients undergoing coronary angiography in a single center. Hyperuricemia was defined by SUA ≥ 6.5 mg/dl. Significant CAD was defined as at least 1 vessel stenosis >50%, while severe CAD was defined as left main and/or three-vessel disease. IPF was measured at admission by routine blood cells count (A Sysmex XE-2100).

RESULTS

We included in our study 2217 patients, of whom 544 had high levels of SUA, while 1673 had normal levels. Hyperuricemics were older, with higher percentage of renal failure, hypertension, dilated cardiomyopathy or valvular disease as indication to angiography, higher levels of creatinine and C-reactive protein (p < 0.001, respectively) when compared to normouricemics. Immature platelet fraction (IPF) was significant higher in hyperuricemic patients (3.96% vs 3.59%, p = 0.004). A progressive direct increase in the IPF values was observed in relation to SUA levels (r = 0.101, p < 0.001), although at multivariate analysis, hyperuricemia did not result as an independent predictor of IPC in 3rd tertile (adjusted OR [95%CI] = 1.21 [0.85-1.71] P = 0.288). When stratifying hyperuricemics and normouricemics according to IPF tertiles (<2.3%; 2.3-3.9%; ≥ 4%), reticulated platelets were not associated to the prevalence of CAD (SUA ≥6.5:80.9 vs 79.3% vs 78.6%, p = 0.60; SUA < 6.5: 79.3% vs 81.3% vs 78.9%, p = 0.878) or severe CAD (SUA ≥6.5: 34.9% vs 38.9% vs 35.2%, p = 0.99; SUA < 6.5: 30.4% vs 33.5% vs 34%, p = 0.192), and the results were confirmed at multivariate analysis for CAD (SUA ≥6.5: adjusted OR [95%CI] = 1.11 [0.81-1.51] P = 0.524, SUA < 6.5: adjusted OR [95%CI] = 0.89 [0.75-1.05] P = 0.170) or severe CAD (SUA ≥6.5: adjusted OR [95%CI] = 1.03 [0.81-1.31] P = 0.795; SUA < 6.5: adjusted OR [95%CI] = 1.10 [0.96-1.26] P = 0.192).

CONCLUSIONS

In the present study we found a direct relationship between SUA levels and IPF values; however, hyperuricemia did not result as an independent predictor of higher IPF tertile values. Neither in hyperuricemics nor in normouricemics higher IPF were independently associated to the prevalence of CAD or severe CAD.

Uric Acid and Cardiovascular Disease: An Update From Molecular Mechanism to Clinical Perspective

Uric acid (UA) is the end product of purine nucleotide metabolism in the human body. Hyperuricemia is an abnormally high level of UA in the blood and may result in arthritis and gout. The prevalence of hyperuricemia has been increasing globally. Epidemiological studies have shown that UA levels are positively correlated with cardiovascular diseases, including hypertension, atherosclerosis, atrial fibrillation (AF), and heart failure (HF). Hyperuricemia promotes the occurrence and development of cardiovascular diseases by regulating molecular signals, such as inflammatory response, oxidative stress, insulin resistance/diabetes, endoplasmic reticulum stress, and endothelial dysfunction. Despite extensive research, the underlying molecular mechanisms are still unclear. Allopurinol, a xanthine oxidase (XO) inhibitor, has been shown to improve cardiovascular outcomes in patients with HF, coronary heart disease (CHD), type 2 diabetes (T2D), and left ventricular hypertrophy (LVH). Whether febuxostat, another XO inhibitor, can improve cardiovascular outcomes as well as allopurinol remains controversial. Furthermore, it is also not clear whether UA-lowering treatment (ULT) can benefit patients with asymptomatic hyperuricemia. In this review, we focus on the latest cellular and molecular findings of cardiovascular disease associated with hyperuricemia and clinical data about the efficacy of ULT in patients with cardiovascular disease.

[Asymptomatic Hyperuricemia and Risk Of Cardiovascular and Renal Diseases]

Asymptomatic hyperuricemia (HU) is common in the population and significantly contributes to the general cardiovascular risk. Despite extensive study of this condition there is still no conclusive answers to questions about detection of asymptomatic HU and its effect on the risk for development and progression of cardiovascular and kidney diseases. This review summarizes key information about these issues, which has been accumulated by the present time.

Uric acid and cardiometabolic diseases

Hyperuricemia, which has been considered as a cause of gout and nephrolithiasis has recently been suggested to be associated with hypertension, coronary heart disease, heart failure, atrial fibrillation, insulin resistance, and nonalcoholic fatty liver disease. Several clinical and experimental studies have supported uric acid (UA) as an independent risk factor for predicting disease development along with the traditional risk factors. The mechanism by which UA causes cardiometabolic disease has not been fully elucidated to date; however, it has been explained by several hypotheses such as oxidative stress, reduced nitric oxide bioavailability, inflammation, endothelial dysfunction, and so on. Although evidence of the preventive and therapeutic effects of UA lowering therapy on cardiometabolic diseases is still insufficient, it is expected to be considered as a new treatment strategy for such diseases through additional, carefully designed, large-scale clinical studies.

The differential role of uric acid - The purpose or cause of cardiovascular diseases?

For 40 years many studies have been conducted to verify the connection between serum uric acid concentration and cardiovascular diseases, such as myocardial infarction. Unfortunately, it remains unclear which form of uric acid - prooxidant or antioxidant - could be a predictive marker of cardiovascular disease, especially in patients after myocardial infarction. It is well-known that uric acid is an organic compound and the water-soluble final product of purine catabolism, which is catalysed by xanthine oxidoreductase and excreted by kidneys. An increased concentration of UA in human plasma leads to diseases like tumours, renal disorders, atherosclerosis, hypertension, diabetes, metabolic syndrome, polycythaemia vera, haemolytic anaemias, ischemia, oxidative stress, and rare genetic disorders connected with UA degradation. Epidemiological studies have shown that UA might be a marker of oxidative stress, progression of inflammation, or renal disease. A fortiori, it is possible that could also be a predictor for short/long-term survival of patients with CVD. Evidence provided by multiple studies is controversial and mutually exclusive. Among 71 studies the most of them found an independent association between SUA and CVD risk. Some of those studies confirm that CVD risk is higher in women who had elevated SUA levels. On the other hand, many studies reached the opposite conclusion and did not find any relationship between SUA and CVD mortality and morbidity.

Sex differences in uric acid and NT-pro BNP assessments during coronary severity

To investigate the correlation between uric acid (UA) and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels and coronary artery severity in acute coronary syndrome patients of different sexes.A total of 134 patients with acute coronary syndrome (ACS) were investigated. According to sex, there were 96 cases in male group and 38 cases in female group. According to the number of diseased vessels, the degree of coronary artery lesion was determined and divided into negative group (n = 21), single vessel lesion group (n = 43), double vessel lesion group (n = 38), and 3 vessel lesion group (n = 32).Univariate analysis showed that UA, NT-proBNP was correlated with the severity of ACS (P < .05). UA was an independent risk factor for the severity of coronary artery disease in female group (P < .05), but not in male group (P > .05). There was no significant correlation between NT-proBNP and severity of coronary artery disease in different sex (P > .05).UA was significantly correlated with the severity of coronary heart disease, especially in women, but not in men. The level of NT-proBNP was positively correlated with the severity of coronary artery, but no significant difference was found in different sexes.

A U-shaped association between serum uric acid with all-cause mortality in normal-weight population

BACKGROUND

It is uncertain how serum uric acid (SUA) associated with all-cause mortality among people with normal weight, hence was explored in this study.

METHODS

We enrolled participants from 1999 to 2006 National Health and Nutrition Examination Survey (NHANES) that had mortality status through 31 December 2015. We estimated adjusted hazard ratios (HRs) and 95% confidence intervals (CI) for all-cause mortality using Cox proportional hazard models, and propensity score analyses were performed. We also performed restricted cubic splines to demonstrate the nonlinear relationship, and used subgroup analysis to examine the effect modification.

RESULTS

We enrolled 6169 participants (2905 men and 3264 women, mean age 42.3 ± 21.4 years) and 1060 (17.2%) cases of all-cause mortality occurred during the mean follow-up of 11.9 years. When using the lowest quartile of SUA as referent, the multivariable HRs for all-cause mortality increased in not parallel with the quartiles of SUA (HRs were 0.92 (95%CI: 0.68, 1.23), 1.10 (95%CI: 0.82, 1.47), and 1.08 (95%CI: 0.80, 1.45) from the second to the fourth quartiles, respectively. When treating SUA as continuous variable, the HRs for all-cause mortality were 1.07 (95%CI: 1.00, 1.15; P = 0.046), 1.03 (95%CI: 0.94, 1.12; P = 0.518) and 1.15 (95%CI: 1.01, 1.31; P = 0.032) in all population, male and female subjects, respectively. Elevated SUA was associated with all-cause mortality and the propensity scores analysis showed the similar results. Subgroup analysis showed SUA was an independent risk of all-cause mortality in female (HR1.17, 95%CI: 1.05, 1.31, P = 0.005), people aged <60 years (HR1.18, 95%CI: 1.03, 1.35, P = 0.018), non-diabetic population (HR1.10, 95%CI: 1.02, 1.18, P = 0.017) and people with eGFR<90 (HR1.10, 95%CI: 1.02, 1.19, P = 0.016). Smoothing spline plots suggested the optimal SUA for the lowest risk of all-cause mortality was approximately 4.7 mg/dl.

CONCLUSION

In normal-weight population, SUA was seemed to be a U-shaped relationship with all-cause mortality.

Relationship between serum uric acid level and all-cause and cardiovascular mortality in population with obesity

BACKGROUND

We aimed to investigate the association between serum uric acid (SUA) and all-cause or cardiovascular mortality among participants with obesity.

METHOD

All participants were included from the 1999 to 2014 National Health and Nutrition Examination Survey with follow-up mortality assessment through 31 December 2015. Cox proportional hazards models were built to estimate adjusted HRs and 95% CIs for mortality according to baseline uric acid in quartiles. Obesity was defined as body mass index ≥30 (kg/m²). Generalised additive model (GAM) and two-piecewise linear regression models were performed to explore any non-linearity in associations.

RESULTS

There were 12 637 adults with obesity eligible for analysis. There were 999 (7.91%) all-cause and 147 (1.16%) cardiovascular mortality occurred during the mean follow-up of 98.11 months. Comparing with the lowest quartile of SUA, the highest SUA group did not have significant association with all-cause (HR 1.08, 95% CI 0.76 to 1.52) and cardiovascular mortality (HR 1.63, 95% CI 0.58 to 4.53) after adjusting for various confounding factors. GAM and two-piecewise linear regression model demonstrated a non-linearly relationship between SUA and all-cause mortality, and the corresponding cut-off point was 6.5 mg/dL. However, there is no significant relationship between uric acid and cardiovascular death on both sides of the cut-off value of 6.1 mg/dL.

CONCLUSIONS

SUA showed a J-shaped relationship with all-cause mortality, but no significant with cardiovascular mortality in adults with obesity.

U-Shaped Association of Serum Uric Acid With All-Cause and Cause-Specific Mortality in US Adults: A Cohort Study

BACKGROUND

In addition to the controversy regarding the association of hyperuricemia with mortality, uncertainty also remains regarding the association between low serum uric acid (SUA) and mortality. We aimed to assess the relationship between SUA and all-cause and cause-specific mortality.

METHODS

This cohort study included 9118 US adults from the National Health and Nutrition Examination Survey (1999-2002). Multivariable Cox proportional hazards models were used to evaluate the relationship between SUA and mortality. Our analysis included the use of a generalized additive model and smooth curve fitting (penalized spline method), and 2-piecewise Cox proportional hazards models, to address the nonlinearity between SUA and mortality.

RESULTS

During a median follow-up of 5.83 years, 448 all-cause deaths occurred, with 100 cardiovascular disease (CVD) deaths, 118 cancer deaths, and 37 respiratory disease deaths. Compared with the reference group, there was an increased risk of all-cause, CVD, cancer, and respiratory disease mortality for participants in the first and third tertiles of SUA. We further found a nonlinear and U-shaped association between SUA and mortality. The inflection point for the curve was found at a SUA level of 5.7 mg/dL. The hazard ratios (95% confidence intervals) for all-cause mortality were 0.80 (0.65-0.97) and 1.24 (1.10-1.40) to the left and right of the inflection point, respectively. This U-shaped association was observed in both sexes; the inflection point for SUA was 6 mg/dL in males and 4 mg/dL in females.

CONCLUSION

Both low and high SUA levels were associated with increased all-cause and cause-specific mortality, supporting a U-shaped association between SUA and mortality.

Association of Serum Uric Acid with Cardiovascular Disease Risk Scores in Koreans

As the prevalence of gout and hyperuricemia increases, the comorbidities of gout and hyperuricemia have become a public health burden. In particular, risks of cardiovascular disease (CVD)-related complications are increasing. However, a few guidelines exist for the management of hyperuricemia. This cross-sectional study aimed to investigate the association of serum uric acid with CVD risk in the general population of Korean adults. We examined cross-sectional data from the first and second years of the seventh Korea National Health and Nutrition Examination Survey 2016–2017. Among 16,277 participants, 8781 were analyzed. We estimated the CVD risk using a 10-year CVD risk score prediction formula. There was a significant association of serum uric acid with 10-year CVD risk scores after adjusting for physical activity, body mass index, serum creatinine, and alcohol consumption in both sexes (p < 0.001). In the fitted fractional polynomial model, an approximate U-shaped association between serum uric acid levels and 10-year CVD risk scores was found in men. At the serum uric acid level of 6.9 mg/dL, the CVD risk was lowest. An approximate J-shaped association between serum uric acid levels and 10-year CVD risk scores was found in women. Our study showed that hyperuricemia was associated with an increased CVD risk. Hypouricemia was also associated with an increased CVD risk in men. We, therefore, recommend proper management of uric acid levels in the general population to reduce CVD risks.