Lower uric acid is associated with poor short-term outcome and a higher frequency of posterior arterial involvement in ischemic stroke

Dual effects of serum urate on stroke risk and prognosis: insights from Mendelian randomization

Background

To investigate the causal associations of serum urate (SUA) with stroke risk and prognosis using Mendelian randomization (MR) and the potential mediating role of stroke risk factors in the causal pathways.

Methods

We used the random-effects inverse variance weighting (IVW) as our primary method. We initially performed two-sample univariable MR (UVMR) to identify the causal associations of SUA (n = 437,354) with any stroke (AS, FinnGen: n = 311,635; MEGASTROKE: n = 446,696), ischemic stroke (IS, FinnGen: n = 212,774; MEGASTROKE: n = 440,328), intracranial hemorrhage (ICH, FinnGen: n = 343,663; ISGC: n = 3,026), functional outcome after ischemic stroke at 90d (n = 4,363), and motor recovery within 24 months after stroke (n = 488), and then multivariable MR (MVMR) to estimate the direct causal effects of SUA on these outcomes, adjusting for potential confounders. Finally, we further conducted a two-step MR to investigate the potential mediating role of body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), and estimated glomerular filtration rate (eGFR) in the identified causal pathways.

Results

Genetically predicted elevated SUA levels were significantly associated with increased risk of AS (meta-analysis: OR = 1.09, 95% CI [1.04-1.13], p = 3.69e-05) and IS (meta-analysis: OR = 1.10, 95% CI [1.01-1.19], p = 0.021) and with improved poor functional outcome after ischemic stroke at 90d (OR = 0.81, 95% CI [0.72-0.90], p = 1.79e-04) and motor recovery within 24 months after stroke (OR = 1.42, 95% CI [1.23-1.64], p = 2.15e-06). In MVMR, SBP and DBP significantly attenuated the causal effects of SUA on AS, IS, and functional outcome after ischemic stroke at 90d and motor recovery within 24 months after stroke. Further mediation analyses showed that SBP mediated 52.4 and 34.5% of the effects of SUA on AS and IS, while DBP mediated 28.5 and 23.4% of the causal effects, respectively.

Conclusion

This study supports the dual role of genetically predicted SUA in increasing stroke risk, especially ischemic stroke risk, and in improving functional outcome and motor recovery. SBP and DBP are key mediators lying on the causal pathways of SUA with AS and IS.

The Influence of Agricultural Work and Plasma Uric Acid on Hospital Admission for Alzheimer's Disease

BACKGROUND

Exposure to environmental neurotoxins associated with agricultural work, such as pesticides, may be a risk factor for neurodegenerative disorders such as Alzheimer's (AD) and Parkinson's (PD) diseases. There is strong evidence that such exposure is associated with the development of PD; for AD the current evidence is equivocal. Several mechanisms are proposed to mediate this environmental toxicity, one of which is oxidative stress. Uric acid (UA) is an endogenous antioxidant, low levels of which are also implicated in neurodegenerative disease.

OBJECTIVE

This study aimed to determine whether agricultural work was a risk factor for AD in a population in which its association with PD was established, and whether UA was also associated with AD in this cohort.

METHODS

Hospital records of subjects meeting criteria for AD (n = 128) or vascular dementia (VaD) (n = 178) after hospital admission for symptoms of dementia were studied. History of agricultural work and plasma UA were recorded and their relationship to diagnosis determined.

RESULTS

In contrast to previous findings in this population in which agricultural work was strongly associated with PD, a history of agricultural work was not over-represented in hospital admission for AD versus VaD. AD was associated with a reduced level of circulating UA compared with VaD.

CONCLUSION

Agricultural work as a likely proxy for exposure to pesticides appears not to be a risk factor for AD to the extent found in PD, perhaps reflecting their differences in neuronal pathology. Nevertheless, findings with UA suggests that oxidative stress may be an important factor in AD pathogenesis.

Uric Acid and Cognitive Impairment in Patients with Acute Ischemic Stroke: A Meta-Analysis

Serum uric acid (UA) has been suggested to be correlated with outcomes after stroke. We performed a meta-analysis to evaluate the association between serum UA and post-stroke cognitive impairment (PSCI) in patients with acute ischemic stroke (AIS). Relevant observational studies were identified by search of electronic databases including PubMed, Embase, and Web of Science. A randomized-effect model incorporating the possible between-study heterogeneity was used to pool the results. Overall, eleven studies with 4246 patients of AIS were included, 2073 (48.8%) of them had PSCI. Pooled results showed that patients with PSCI had significantly higher level of serum UA as compared to those without PSCI (mean difference: 35.70 μmol/l, 95% confidence interval (CI): 8.36 to 63.01, p=0.01; I2=95%). Subgroup analysis showed significant higher level of serum UA in patients with PSCI evaluated during follow-up of 3 months to 3 years, but not for those evaluated during hospitalization (p for subgroup difference=0.01). In addition, results of meta-analysis also showed that compared to patients with lower serum UA, AIS patients with higher serum UA had increased risk of PSCI (odds ratio: 1.33, 95% CI: 1.02 to 1.73, p=0.04; I2=72%). Higher level of serum UA after disease onset may be a marker of increased risk of PSCI in patients with AIS. Although these findings need to be validated in large-scale prospective studies, the possible mechanisms underlying the association between UA and PSCI should be also investigated.

Higher uric acid is associated with better discharge recovery and short-term outcome in stroke patients treated with thrombolysis

BACKGROUND

Uric acid (UA) possesses antioxidant features and potential neuroprotective effects. However, conflicting results regarding the association between serum uric acid (SUA) levels and the prognosis of stroke have been obtained. We aimed to assess whether SUA is related to discharge recovery and short-term outcomes in patients who underwent thrombolysis therapy.

METHODS

We recruited 393 consecutive patients who were diagnosed with acute ischaemic stroke (AIS) and treated with thrombolysis. The demographic information, including sex and age, was collected. Haematology tests, including SUA, fasting plasma glucose (FPG), and blood lipid parameters, were performed under fasting conditions the morning after admission. The modified Rankin Scale (mRS) was used to assess the functional outcome of patients at discharge and 3 months after onset.

RESULTS

A negative correlation was observed between the levels of SUA and the National Institute of Health Stroke Scale (NIHSS) score at discharge (r = - 0.171, P = 0.003). Additionally, a positive correlation was observed between the levels of SUA and the difference between the baseline NIHSS and discharge NIHSS (r = 0.118, P = 0.032). The levels of SUA in the patients with good outcomes (353.76 ± 93.05) were higher than those in the patients with poor outcomes (301.99 ± 92.24; P = 0.015) at 3 months. The multivariate logistic regression analysis demonstrated that a higher SUA level (odds ratio 0.988, 95% confidence interval 0.985-0.991, P = 0.002) was an independent predictor of a good outcome at 3 months.

CONCLUSION

Higher SUA levels were associated with better discharge recovery and 3-month outcomes in patients with ischaemic stroke who received thrombolysis.

Relationship between Uric Acid Level and Severity of Acute Primary Cerebral Infarction: A Cross-Sectional Study

Numerous studies have shown that uric acid (UA) is associated with cerebrovascular disease, but whether UA is a protective factor or worsens the risk of developing cerebrovascular disease remains controversial. This study investigated the relationship between UA levels detected at admission and the severity of acute primary cerebral infarction. This cross-sectional study enrolled patients with acute primary cerebral infarction (N = 238, 157 men). We designated the levels of serum UA measured at the time of admission as the independent variable and the degree of neurological impairment at admission as the dependent variable. The National Institutes of Health Stroke Scale (NIHSS) was used to assess the extent of neurological dysfunction: NIHSS ≤ 5, minor stroke; NIHSS > 5, moderate to severe stroke. There was a statistically significant difference in UA levels between patients with mild cerebral infarctions (NIHSS ≤ 5) and those with moderate or severe cerebral infarctions (NIHSS > 5) (P < 0.0001). After adjusting for confounding factors, the serum UA level was found to be nonlinearly related to NIHSS, and the inflection point was 372 μmol/L. The extent of the influence and confidence interval was 0.99 (0.98, 0.99) on the left side of the inflection point and 1.00 (1.00, 1.01) on the right side. There was a nonlinear relationship between the UA level measured on admission and the degree of neurological impairment in patients with acute primary cerebral infarction. When UA was <372 μmol/L, it was negatively correlated with the degree of neurological impairment in patients with acute cerebral infarction, but when UA was ≥372 μmol/L, the protective effect of UA disappeared.

Agricultural work and reduced circulating uric acid are both associated with initial hospital admission for Parkinson's disease

Monoamine oxidase type B inhibitors act in Parkinson's disease (PD) via potentiation of dopamine, but may also have neuroprotective effects by reducing oxidative damage. Oxidative damage is also a feature of environmental toxins, including pesticides, that are an established risk factor for PD. Another risk factor is low circulating uric acid (UA), which may relate to UA being the major endogenous antioxidant in the human body. We have undertaken a study of 192 initial admissions for PD in a general hospital neurology department in a partly rural region of Southern China to determine if there is an increased rate of PD in agricultural workers who have a high risk of exposure to pesticides, and how it may relate to deficits in UA. We found a disproportionately high number of agricultural workers admitted with PD (66.7% vs. 54.3% of all neurology admissions) and that PD subjects have a substantial reduction in UA. This is further reduced in agricultural workers and thus may contribute to the increased vulnerability of this group to PD.

Peripheral Monocyte Count Predicts Outcomes in Patients with Acute Ischemic Stroke Treated with rtPA Thrombolysis

The aim of this study was to investigate the predictive value of the monocyte count as a prognostic biomarker on 90 days in patients with acute ischemic stroke (AIS) treated with recombinant tissue plasminogen activator (rtPA) thrombolysis. In total, 206 patients with AIS treated in our institute between 2013 and 2018 were retrospectively enrolled. All patients received rtPA thrombolytic therapy within 4.5 h of AIS onset. Using receiver operating characteristic (ROC) curve analysis, patients were divided into two groups according to monocyte count: a low monocyte count (LMC) group (monocytes < 0.53 × 10⁹/L) and a high monocyte count (HMC) group (monocytes ≥ 0.53 × 10⁹/L). Patients' functional outcomes 90 days after AIS were assessed using the modified Rankin Scale. More patients had a poor outcome in the HMC group than in the LMC group (49.32% vs.31.58%, p = 0.012). Multivariate logistic regression analysis revealed that infarct volume (odds ratio = 1.03, 95% confidence interval 1.01-1.04, p < 0.001), systolic pressure at admission (odds ratio = 1.02, 95% confidence interval 1.00-1.04, p = 0.016), fasting blood glucose at admission (odds ratio = 1.41, 95% confidence interval 1.18-1.67, p < 0.001), and monocyte count ≥ 0.53 × 10⁹/L (odds ratio = 2.25, 95% confidence interval 1.09-4.62, p = 0.028) were independently associated with a poor outcome in AIS patients treated with rtPA thrombolysis. A peripheral monocyte count ≥ 0.53 × 10⁹/L is an independent prognostic marker on 90-days in patients with AIS treated with rtPA thrombolysis.

Relationship between infarct size and serum uric acid levels during the acute phase of stroke

Introduction

Uric acid has gained considerable attention as a potential neuroprotective agent in stroke during the last decades, however, its role in the pathophysiology of ischemic stroke remains poorly understood. A serial evaluation of uric acid levels during the acute phase of stroke and its association with infarct size on magnetic resonance imaging is lacking.

Methods

We present a cohort study of 31 patients with ischemic stroke who were not candidates for thrombolysis according to current criteria at the time. We performed daily measurements of serum uric acid and total antioxidant capacity of plasma during the first week after symptoms onset and 30 days after. Infarct size was determined in the acute phase by a DWI sequence and the final infarct size with a control MRI (FLAIR) at day 30.

Results

Uric acid significantly decreases between days 2 to 6 compared to day 1, after adjustment by sex, age and DWI at diagnosis, with a nadir value at 72h. A mixed model analysis showed a negative association between DWI at diagnosis and uric acid evolution during the first week after stroke. Moreover, multivariable linear regression of uric acid values during follow up on DWI volumes demonstrated that DWI volume at diagnosis is negatively associated with uric acid levels at day 3 and 4. There were no significant associations between total antioxidant capacity of plasma and DWI at diagnosis, or FLAIR at any point.

Discussion

Patients with larger infarcts exhibited a significant decrease in serum uric acid levels, accounting for a more prominent reactive oxygen species scavenging activity with subsequent consumption and decay of this antioxidant. The different kinetics of total antioxidant capacity of plasma and serum uric acid levels suggests a specific role of uric acid in the antioxidant response in ischemic stroke.