The association between serum uric acid levels and ischemic stroke in essential hypertension patients

Serum uric acid levels and intracerebral hemorrhage: A two-sample Mendelian randomization study

OBJECTIVE

Previous observational studies have generated controversy regarding the correlation between serum uric acid (UA) levels and intracerebral hemorrhage (ICH), with the causal relationship remaining uncertain. To assess the potential causal relationship between serum UA levels and ICH, two-sample Mendelian randomization analysis was applied.

METHODS

Single-nucleotide polymorphisms (SNPs) closely associated with serum UA were retrieved from the genome-wide association study (GWAS) database, including 580,505 individuals of European descent. A total of 27 and 251 SNPs were chosen as instrumental variables. Summary data for ICH included 1935 cases and 471,578 controls. Two-sample MR analyses, including inverse-variance weighted (IVW), MR-Egger, weighted median, and weighted mode methods, were employed to assess the potential causal relationship between serum UA levels and ICH, with odds ratios (ORs) as effect estimates. Heterogeneity was evaluated using Cochran's Q test, and sensitivity analyses were conducted using the leave-one-out method.

RESULTS

The IVW analysis revealed that a 1 mg/dL increase in serum UA was associated with a 16.5 % higher risk of ICH (OR 1.165, 95 % CI 1.01-1.34, P = 0.034), while a 1 quantile increase in serum UA was associated with a 25.9 % higher risk (OR 1.259, 95 % CI 1.091-1.46, P = 0.002). Cochran's Q test showed no evidence of heterogeneity. No horizontal pleiotropy was detected. The sensitivity analysis using the leave-one-out method supported the robustness and reliability of our results.

CONCLUSION

The study reveals that elevated serum UA levels are causally linked to ICH, suggesting the potential applicability of serum UA as a biomarker for the occurrence of ICH.

A New Perspective on the Prediction and Treatment of Stroke: The Role of Uric Acid

Stroke, a major cerebrovascular disease, has high morbidity and mortality. Effective methods to reduce the risk and improve the prognosis are lacking. Currently, uric acid (UA) is associated with the pathological mechanism, prognosis, and therapy of stroke. UA plays pro/anti-oxidative and pro-inflammatory roles in vivo. The specific role of UA in stroke, which may have both neuroprotective and damaging effects, remains unclear. There is a U-shaped association between serum uric acid (SUA) levels and ischemic stroke (IS). UA therapy provides neuroprotection during reperfusion therapy for acute ischemic stroke (AIS). Urate-lowering therapy (ULT) plays a protective role in IS with hyperuricemia or gout. SUA levels are associated with the cerebrovascular injury mechanism, risk, and outcomes of hemorrhagic stroke. In this review, we summarize the current research on the role of UA in stroke, providing potential targets for its prediction and treatment.

Association of hyperuricemia with cardiovascular diseases: current evidence

The aim of the present study is to present a historical and unified perspective on the association of serum uric acid (SUA) in the cause of cardiovascular diseases (CVDs). The association of hyperuricemia (HUC) with CVD begun to be appreciated in the middle 1950s and early 1990s when clinical evidence was shown on the association of HUC with CVD. However, this association was disputed by several investigators including the Framingham group and by professional societies, like the American Heart Association and the American Society of Hypertension. This dispute was weakened or reversed by later studies, which showed a positive association of HUC with CVD, CHD, HF, CKD, and stroke, mediated by several risk factors, both molecular such as, oxidative stress, inflammatory stress, insulin resistance, and endothelial dysfunction, as well as clinical factors such as, atherosclerosis, hypertension, metabolic syndrome, and type 2 diabetes mellitus. The great majority of recent studies show a positive association of HUC with CVDs, and CKD. However, the cutoff of the damaging levels of SUA have not been established as yet. The European Society of Hypertension (ESH) Treatment Guidelines have proposed a cutoff level of SUA for CVD > 7 mg/dl for men and > 6 mg/dl for women. In contrast, the URRAH study has shown a SUA level of 4.7 mg/dl for all-cause mortality and 5.6 mg/dl for CV mortality. These levels are lower than the SUA levels proposed by the ESH, which are consistent with HUC. For a better understanding of this association, a Medline search of the English literature was conducted between 2015 and 2022 and 44 pertinent papers were selected. These papers together with collateral literature will be discussed in this review.

The Role of Oxidative Stress in Acute Ischemic Stroke-Related Thrombosis

Acute ischemic stroke is a serious life-threatening disease that affects almost 600 million people each year throughout the world with a mortality of more than 10%, while two-thirds of survivors remain disabled. However, the available treatments for ischemic stroke are still limited to thrombolysis and/or mechanical thrombectomy, and there is an urgent need for developing new therapeutic target. Recently, intravascular oxidative stress, derived from endothelial cells, platelets, and leukocytes, has been found to be tightly associated with stroke-related thrombosis. It not only promotes primary thrombus formation by damaging endothelial cells and platelets but also affects thrombus maturation and stability by modifying fibrin components. Thus, oxidative stress is expected to be a novel target for the prevention and treatment of ischemic stroke. In this review, we first discuss the mechanisms by which oxidative stress promotes stroke-related thrombosis, then summarize the oxidative stress biomarkers of stroke-related thrombosis, and finally put forward an antithrombotic therapy targeting oxidative stress in ischemic stroke.

Association of serum uric acid levels with cardiovascular and all-cause mortality in hypertensive patients in China: a cohort study

Purpose

The present study aimed to assess the association of elevated serum uric acid (SUA) and hypouricemia with all-cause mortality and cardiovascular mortality in Chinese hypertensive patients.

Methods

In the present prospective cohort, 9325 hypertensive patients from Dongguan, China were enrolled from 2014 to 2018 for analysis. Participants were categorised by quintiles of SUA. The HRs and 95% CIs for the association between SUA, all-cause and cardiovascular mortality were evaluated using the multivariate Cox regression model. After adjusting for multiple confounders, restricted cubic spline analysis was conducted to demonstrate the shape of relationship.

Results

After a median follow-up of 4.18 years for 9325 participants, there were 409 (4.4%) and 151 (1.6%) reported cases of all-cause and cardiovascular mortality, respectively. By using the third quintile of SUA (6.68 mg/dL to <7.55 mg/dL for men, 5.63 mg/dL to <6.42 mg/dL for women) as reference, the highest quintiles of SUA were associated with an elevated risk of all cause (HR: 1.34, 95% CI 1.00 to 1.80) in the crude model, but the association was not significant after adjusting for multiple comparisons. The association between low SUA and mortality and the dose–response analysis on the non-linearity of SUA–mortality relationship were not statistically significant.

Conclusions

Although the association between SUA levels, all-cause and cardiovascular disease mortality did not appear to be significant among Chinese hypertensive patients, the findings might be confounded by their medical conditions. Further studies are needed to verify the optimal SUA levels for hypertensive patients.

Uric Acid Expression in Carotid Atherosclerotic Plaque and Serum Uric Acid Are Associated With Cerebrovascular Events

BACKGROUND

Uric acid (UA) concentration within carotid plaque and its association with cerebrovascular events have not been detected or quantified. Systemically, serum UA is a marker of inflammation and risk factor for atherosclerosis. However, its association with carotid plaque instability and stroke pathogenesis remains unclear. In patients undergoing carotid endarterectomy, we aimed to determine whether UA is present differentially in symptomatic versus asymptomatic carotid plaques and whether serum UA is associated with cerebrovascular symptoms (stroke, transient ischemic attack, or amaurosis fugax).

METHODS

Carotid atherosclerotic plaques were collected during carotid endarterectomy. The presence of UA was assessed using Gomori methenamine silver staining as well as anti-UA immunohistochemical staining and its quantity measured using an enzymatic colorimetric assay. Clinical information was obtained through a retrospective review of data.

RESULTS

UA was more commonly detected in symptomatic (n=23) compared with asymptomatic (n=9) carotid plaques by Gomori methenamine silver (20 [86.9%] versus 2 [22.2%]; P=0.001) and anti-UA immunohistochemistry (16 [69.5%] versus 1 [11.1%]; P=0.004). UA concentration was higher in symptomatic rather than asymptomatic plaques (25.1 [9.5] versus 17.9 [3.8] µg/g; P=0.021). Before carotid endarterectomy, serum UA levels were higher in symptomatic (n=341) compared with asymptomatic (n=146) patients (5.9 [interquartile range, 4.6-6.9] mg/dL versus 5.2 [interquartile range, 4.6-6.2] mg/dL; P=0.009).

CONCLUSIONS

The current study supports a potential role of UA as a potential tissue participant and a systemic biomarker in the pathogenesis of carotid atherosclerosis. UA may provide a mechanistic explanation for plaque instability and subsequent ischemic cerebrovascular events.

Serum Uric Acid Levels at Admission Could Predict the Chronic Post-stroke Fatigue

Background

Post-stroke fatigue (PSF) is a frequent complication of stroke. Serum uric acid (SUA) is frequently thought to be a risk factor for stroke. This study aimed to investigate whether SUA also played a role in PSF.

Methods

Subjects with ischemic stroke were screened from The First Affiliated Hospital of Wenzhou Medical University between January 2020 and October 2020. Patients' fatigue symptoms were assessed by the Fatigue severity scale (FSS). To investigate the relationship between SUA and PSF, binary logistic regression analysis was conducted, with the confounders being controlled. SUA levels were divided into four layers (Q1 ≤ 245 μmol/L; Q2 246–308 μmol/L; Q3 309–365 μmol/L; Q4 ≥366 μmol/L) based on the quartiles.

Results

SUA levels were significantly higher in the PSF group (345.96 ± 73.78 μmol/L) than the non-PSF group (295.97 ± 87.8 μmol/L, P < 0.001). There were no differences in any other variables between these two groups. After adjusting the confounders, the risk of PSF in the Q4 layer (≥366 μmol/L) was 6.05 times (95% CI 1.79–20.43, P = 0.004) higher than that in Q1 (≤245 μmol/L).

Conclusion

High SUA at admission was an independent risk factor for fatigue 1 year after stroke onset. High SUA (≥366 μmol/L) during stroke deserves more attention, and active control of high SUA levels may be beneficial to reduce the incidence of PSF in the chronic stage following stroke.

Prospective Study of Serum Uric Acid Levels and First Stroke Events in Chinese Adults With Hypertension

Objectives: We investigated the association between serum uric acid (SUA) levels and the risk of the first stroke in Chinese adults with hypertension.

Methods: A total of 11, 841 hypertensive patients were selected from the Chinese Hypertension Registry for analysis. The relationship between SUA levels and first stroke was determined using multivariable Cox proportional hazards regression, smoothing curve fitting, and Kaplan–Meier survival curve analysis.

Results: During a median follow-up of 614 days, 99 cases of the first stroke were occurred. Cox proportional hazards models indicated that SUA levels were not significantly associated with the first stroke event [adjusted-hazard ratio (HR) per SD increase: 0.98, 95% CI 0.76–1.26, P = 0.889]. In comparison to the group without hyperuricemia (HUA), there were no significantly higher risks of first stroke events (adjusted-HR: 1.22, 95% CI 0.79–1.90, P = 0.373) in the population with HUA. However, in the population less than 60 years old, subjects with HUA had a significantly higher risk of the first stroke than the population without HUA (adjusted-HR: 4.89, 95% CI 1.36–17.63, P = 0.015). In subjects older than 60 years, we did not find a significant relationship between HUA and first stroke (adjusted-HR: 0.97, 95% CI 0.60–1.56, P = 0.886). Survival analysis further confirmed this discrepancy (log-rank P = 0.013 or 0.899 for non-aging or aging group).

Conclusion: No significant evidence in the present study indicated that increased SUA levels were associated with the risk of first stroke in the Chinese adults with hypertension. Age played an interactive role in the relationship between HUA and the first stroke event.

Uric Acid and Clinical Outcomes in Young Patients with Ischemic Stroke

BACKGROUND AND PURPOSE

There is limited available evidence for the relationship between uric acid (UA) levels and ischemic stroke in young adults. We aimed to explore the association between UA levels and acute ischemic stroke (AIS) in young patients.

MATERIALS AND METHODS

This was a prospective and observational study. We recruited young patients aged 18-45 years with AIS at our tertiary hospital. Patients were categorized into four groups according to quartiles of UA levels. The primary outcome was functional outcome at 3 months. The secondary outcomes included stroke severity, in-hospital complications, and functional outcome at discharge. Modified Rankin Scale (mRS) scores were used to assess functional outcome as poor (mRS=2-6) or favorable(mRS=0-1).

RESULTS

A total of 636 patients were enrolled in the current analysis. The four groups were defined as follows: Q1≤289.8 µmol/L, 289.8 µmol/ L<Q2≤349.0 µmol/L, 349.0 µmol/L<Q3≤421 µmol/L, and Q4>421 µmol/L. Multiple logistic regression analysis showed that UA levels were not significantly predictive of functional outcome either at discharge or at 3 months after AIS. However, compared to Q1, higher UA levels were significantly negatively associated with the rate of moderate-severe stroke (NIHSS≥5) at admission (p for trend =0.016). Furthermore, a reduction in the risk for in-hospital pneumonia was significantly associated with higher UA levels compared to Q1 (P for trend < 0.0001).

CONCLUSION

Serum UA was a protective factor for stroke severity and in-hospital pneumonia after AIS in young patients. However, we were unable to identify the predictive significance of UA for functional outcome either at discharge or at 3 months after AIS.

Correlation between serum miR-122 and myocardial damage and ventricular function in patients with essential hypertension

Background

Myocardial damage and decreased ventricular function are risk factors leading to a bad prognosis in patients with essential hypertension (EH). MicroRNAs play important roles in myocardial function impairment in patients with hypertension. The purpose of our research was to investigate the correlation between serum miR-122 and myocardial damage and ventricular functions in EH patients.

Methods

The clinic data of EH patients (group A, n=60) and healthy individuals (group B, n=60) from December 2016 to December 2019 in our hospital were collected and analyzed. Serum miR-122, myocardial damage markers [B-type brain natriuretic peptide (BNP), homocysteine (Hcy), cardiac troponin T (cTnT) and creatine kinase MB isoenzyme (CK-MB)] and cardiac function indicators [ejection fraction (EF), left ventricular septal thickness (IVST), left ventricular isovolumic relaxation time (IVRT), left ventricular end-diastolic diameter (LVEDD), left ventricular posterior wall thickness (LVPWT), and left ventricular end-systolic diameter (LVESD)] were assessed in both groups. The correlation between serum miR-122 and myocardial damage markers and ventricular function indicators was analyzed.

Results

(I) The mean serum miR-122 concentration in group A and group B was 6.86±1.23 and 3.36±1.87 µmol/L, respectively. The serum miR-122 concentration in group A was evidently increased compared with that in group B. (II) The levels of BNP, Hcy, cTnT, and CK-MB in the peripheral blood in group A were evidently increased compared with those in group B (P<0.05). (III) EF and IVRT were evidently decreased in group A compared with that in group B (P<0.05). (IV) Serum miR-122 concentration was positively correlated with the myocardial damage markers BNP, Hcy, cTnT and CK-MB, and serum miR-122 concentration was negatively correlated with the ventricular function indicators EF and IVRT but not significantly correlated with other ventricular function indicators (IVST, LVEDD, LVPWT and LVESD).

Conclusions

The serum miR-122 concentration in EH patients was higher than that in healthy individuals, and miR-122 concentration was positively correlated with myocardial damage markers. Serum miR-122 level was negatively correlated with the ventricular function indicators EF and IVRT but was not significantly correlated with other ventricular function indicators (IVST, LVEDD, LVPWT, and LVESD).

High Uric Acid Level Predicts Early Neurological Deterioration in Intracerebral Hemorrhage

OBJECTIVE

Increased level of serum uric acid (UA) is often considered a risk factor for ischemic stroke. However, there are limited data on the association between UA and intracerebral hemorrhage (ICH). This study aimed to examine the connection between UA and early neurological deterioration (END) in patients with ICH.

METHODS

This is a prospective observational study. Patients with ICH were enrolled from January 2017 to December 2020. END was diagnosed as the Canadian Stroke Scale (CSS) score decreased ≥1 points between admission and 48 hours. UA was measured at admission. Multivariable logistic regression analysis was performed to explore the relationship between serum UA and END.

RESULTS

Of the 498 enrolled patients, 132 (26.5%) were developed with END. Patients with END had a significantly higher level of serum UA (332 vs 270 µmol/L, P < 0.001). Univariate logistic regression analysis indicated that patients with the highest quartile of UA level had an OR of 3.256 (95% CI: 1.849-5.734, P < 0.001) for END compared with those with the lowest quartile of UA level. After adjusting for major confounders, the highest UA quartile remained as an independent predictor for END (OR = 2.282, 95% CI: 1.112-4.685, P = 0.013).

CONCLUSION

Higher serum UA level was independently associated with END in patients with ICH; therefore, intervention to lower UA level may be worth considering.