Effects of uric acid levels on outcome in severe ischemic stroke patients treated with intravenous recombinant tissue plasminogen activator

Serum uric acid and prognosis in acute ischemic stroke: a dose-response meta-analysis of cohort studies

Background

There have been contradictory findings regarding the relationship between serum uric acid levels and prognosis in acute ischemic stroke. Whether this association is nonlinear due to uric acid's paradoxical properties (antioxidant and prooxidant) is unclear.

Methods

We searched PubMed, Web of Science, and Embase databases until December 2022. Cohort studies reporting serum uric acid levels and functional outcome, mortality, or neurological complications in patients with acute ischemic stroke were included. Summary effect estimates were calculated using a random-effect model. Moreover, dose-response relationships were assessed by the generalized least squares trend estimation.

Results

Altogether, 13 cohort studies were identified in this study. Compared to the lowest baseline serum uric acid levels, the highest levels were associated with decreased risk of poor functional outcome (OR = 0.70, 95% CI 0.54-0.91, I2 = 29%), hemorrhagic transformation (OR = 0.15, 95% CI 0.05-0.42, I2 = 79%), and post-stroke depression (OR = 0.04, 95% CI 0.00-0.95, I2 = 89%), but not associated with mortality and symptomatic intracerebral hemorrhage. A nonlinear relationship was observed in poor functional outcome (U-shaped, P for nonlinearity = 0.042), hemorrhagic transformation (inverse, P for nonlinearity = 0.001), and post-stroke depression (inverse, P for nonlinearity = 0.002). In addition, there was a single study reporting a U-shaped association in post-stroke epilepsy (P for nonlinearity <0.001). Furthermore, another study reported a positive curvilinear association in stroke recurrence (P for nonlinearity <0.05). The insufficient number of original articles for some prognostic indicators should be considered when interpreting the results of this meta-analysis.

Conclusion

In patients with acute ischemic stroke, serum uric acid levels are nonlinearly associated with the risk of poor functional outcome (U-shaped). More evidence is needed to confirm the association between serum uric acid levels and neurological complications following acute ischemic stroke.

Association between decreases in serum uric acid levels and unfavorable outcomes after ischemic stroke: A multicenter hospital-based observational study

BACKGROUND

The association between clinical outcomes in ischemic stroke patients and decreases in serum uric acid levels, which often occur during the acute phase, remains unknown. Herein, we aimed to investigate the association using a large-scale, multicenter stroke registry.

METHODS

We analyzed 4,621 acute ischemic stroke patients enrolled in the Fukuoka Stroke Registry between June 2007 and September 2019 whose uric acid levels were measured at least twice during hospitalization (including on admission). The study outcomes were poor functional outcome (modified Rankin Scale score ≥3) and functional dependence (modified Rankin Scale score 3-5) at 3 months after stroke onset. Changes in uric acid levels after admission were evaluated using a decrease rate that was classified into 4 sex-specific grades ranging from G1 (no change/increase after admission) to G4 (most decreased). Multivariable logistic regression analyses were used to assess the associations between decreases in uric acid levels and the outcomes.

RESULTS

The frequencies of the poor functional outcome and functional dependence were lowest in G1 and highest in G4. The odds ratios (95% confidence intervals) of G4 were significantly higher for poor functional outcome (2.66 [2.05-3.44]) and functional dependence (2.61 [2.00-3.42]) when compared with G1 after adjusting for confounding factors. We observed no heterogeneity in results for subgroups categorized according to age, sex, stroke subtype, neurological severity, chronic kidney disease, or uric acid level on admission.

CONCLUSIONS

Decreases in serum uric acid levels were independently associated with unfavorable outcomes after acute ischemic stroke.

Association between uric acid and the prognosis of acute ischemic stroke: A systematic review and meta-analysis

AIMS

Meta-analysis was performed to assess the value of serum uric acid in the prognosis of ischemic stroke.

DATA SYNTHESIS

We searched the databases of PubMed, Embase, and Web of Science. The literature we searched was published from the establishment of the database to January 2021. The references of the included literature were also collected. Two researchers sifted through the literature according to the inclusion and exclusion criteria and extracted the data. Stata 16.0 software was used for meta-analysis, and funnel plots were used to evaluate publication bias. Ten studies fulfilled the research criteria and were eventually included, and the analysis results showed that there was no significant association between serum uric acid and the functional outcome (OR = 0.99, 95% CI; 0.97-1.10), poor outcome (OR = 1.07, 95% CI; 0.99-1.15), vascular events (OR = 0.86, 95% CI; 0.52-1.41), and mortality (OR = 1.08, 95% CI; 0.93-1.24) related to ischemic stroke.

CONCLUSIONS

There was no significant correlation between serum uric acid level and prognosis of ischemic stroke.

Prognostic significance of uric acid change in acute ischemic stroke patients with reperfusion therapy

BACKGROUND

Uric acid (UA) is an important endogenous free radical scavenger that has been found to have a neuroprotective effect. However, there is uncertainty about the relationship between UA change and outcome in acute ischemic stroke (AIS) patients with reperfusion therapy.

METHODS

We consecutively enrolled AIS patients with reperfusion therapy. UA was measured upon admission and during hospitalization. The change in UA levels (ΔUA) was determined by calculating the difference between admission UA and the lowest UA among all follow-up measurements, with a positive ΔUA suggesting a decrease in UA levels. Functional outcome was assessed by modified Rankin Scale (mRS) at 3 months. Poor outcome was defined as mRS >2.

RESULTS

A total of 361 patients were included (mean age 68.7 ± 13.9 years, 54.3% males). The mean UA on admission was 355 ± 96.1 μmol/L. The median ΔUA was 121 μmol/L (IQR 50-192 μmol/L) and 18 (5%) patients had increased UA levels. UA on admission was positively associated with good outcome (p for trend = 0.017). When patients were classified into quartiles by ΔUA, patients with the largest decrease in UA (Q4: 199-434 μmol/L) had a higher risk of poor outcome at 3 months compared to patients with the least decrease in UA (Q1: 0-57 μmol/L) (OR 2.55, 95% CI 1.09-5.98, p = 0.031). The risk of poor outcome increased with ΔUA (p for trend = 0.048).

CONCLUSIONS

In patients with reperfusion therapy, high UA on admission was associated with a good 3-month outcome, while a greater decrease in UA was associated with poor outcome.

Prognostic nomogram for patients with minor stroke and transient ischaemic attack

BACKGROUND

Ischaemic stroke and transient ischaemic attack (TIA) share a common cause. We aim to develop and validate a concise prognostic nomogram for patients with minor stroke and TIA.

METHODS

A total of 994 patients with minor stroke and TIA were included. They were split into a derivation (n=746) and validation (n=248) cohort. The modified Rankin Scale (mRS) scores 3 months after onset were used to assess the prognosis as unfavourable outcome (mRS≥2) or favourable outcome (mRS<2).

RESULT

The final model included seven independent predictors: gender, age, baseline National Institute of Health Stroke Scale (NIHSS), hypertension, diabetes mellitus, white blood cell and serum uric acid. The Harrell's concordance index (C-index) of the nomogram for predicting the outcome was 0.775 (95% CI 0.735 to 0.814), which was confirmed by the validation cohort (C-index=0.787 (95% CI 0.722 to 0.853)). The calibration curve showed that the nomogram-based predictions were consistent with actual observation in both derivation cohort and validation cohort.

CONCLUSION

The proposed nomogram showed favourable predictive accuracy for minor stroke and TIA. This has the potential to contribute to clinical decision-making.

Effects of Urinary Kallidinogenase on NIHSS score, mRS score, and fasting glucose levels in acute ischemic stroke patients with abnormal glucose metabolism: A prospective cohort study

Urinary kallidinogenase may assist recovery acute ischemic stroke. This study evaluated the effect of urinary kallidinogenase on National Institute of Health Stroke Scale (NIHSS) score, modified Rankin scale (mRS) score, and fasting glucose levels in patients with acute ischemic stroke (AIS) combined with diabetes mellitus and impaired fasting glucose.Patients with AIS and abnormal glucose metabolism were enrolled in this prospective cohort study and divided into 2 groups. The human urinary kallidinogenase (HUK) group were treated with urinary kallidinogenase and standard treatment; the control group received standard treatment. NIHSS scores, mRS scores, and fasting blood glucose were evaluated and compared.A total of 113 patients were included: 58 in the HUK group and 55 in the control group. NIHSS scores decreased with treatment in both groups (time effect P < .05), but were lower in the HUK group (main effect P = .026). The mRS score decreased in both groups from 10 until 90 days after treatment (time effect P < .05); the 2 groups were similar (main effect, P = .130). Blood glucose levels decreased in both groups 10 days after treatment (time effect, P < .05), but there was no significant treatment effect (main effect, P = .635). Multivariate analysis showed blood uric acid >420 μmol/L (odds ratio [OR]: 0.053, 95% confidence interval [CI]: 0.008-0.350; P = .002) and application of HUK (OR: 0.217, 95% CI: 0.049-0.954; P = .043) were associated with 90% NIHSS recovery. Baseline NIHSS score was independently associated with poor curative effect.Urinary kallidinogenase with conventional therapy significantly improved NIHSS scores in patients with AIS. Urinary kallidinogenase also showed a trend toward lower fasting blood glucose levels, although the level did not reach significance.

Targeting RNS/caveolin-1/MMP signaling cascades to protect against cerebral ischemia-reperfusion injuries: potential application for drug discovery

Reactive nitrogen species (RNS) play important roles in mediating cerebral ischemia-reperfusion injury. RNS activate multiple signaling pathways and participate in different cellular events in cerebral ischemia-reperfusion injury. Recent studies have indicated that caveolin-1 and matrix metalloproteinase (MMP) are important signaling molecules in the pathological process of ischemic brain injury. During cerebral ischemia-reperfusion, the production of nitric oxide (NO) and peroxynitrite (ONOO⁻), two representative RNS, down-regulates the expression of caveolin-1 (Cav-1) and, in turn, further activates nitric oxide synthase (NOS) to promote RNS generation. The increased RNS further induce MMP activation and mediate disruption of the blood-brain barrier (BBB), aggravating the brain damage in cerebral ischemia-reperfusion injury. Therefore, the feedback interaction among RNS/Cav-1/MMPs provides an amplified mechanism for aggravating ischemic brain damage during cerebral ischemia-reperfusion injury. Targeting the RNS/Cav-1/MMP pathway could be a promising therapeutic strategy for protecting against cerebral ischemia-reperfusion injury. In this mini-review article, we highlight the important role of the RNS/Cav-1/MMP signaling cascades in ischemic stroke injury and review the current progress of studies seeking therapeutic compounds targeting the RNS/Cav-1/MMP signaling cascades to attenuate cerebral ischemia-reperfusion injury. Several representative natural compounds, including calycosin-7-O-β-D-glucoside, baicalin, Momordica charantia polysaccharide (MCP), chlorogenic acid, lutein and lycopene, have shown potential for targeting the RNS/Cav-1/MMP signaling pathway to protect the brain in ischemic stroke. Therefore, the RNS/Cav-1/MMP pathway is an important therapeutic target in ischemic stroke treatment.

Associations between Uric Acid Level and 3-Month Functional Outcome in Acute Ischemic Stroke Patients Treated with/without Edaravone

BACKGROUND

Uric acid (UA), an antioxidant with neuroprotective effects, favorably affects stroke outcome. However, the effect has not been examined in patients treated with edaravone, a frequently used free radical scavenger. We investigated whether the use of edaravone affected the relationship between UA levels and outcome in acute ischemic stroke.

METHODS

We retrospectively evaluated 1,114 consecutive ischemic stroke patients with premorbid modified Rankin Scale (mRS) scores <2 admitted within 24 h of onset (mean, 74 years; median UA levels, 333 μmol/L). We divided the patients into 2 groups using the median UA value as a cutoff, a low UA group (≤333 μmol/L; n = 566) and a high UA group (>333 μmol/L; n = 548), and compared their clinical characteristics and favorable outcomes (mRS <2) at 90 days. We investigated the associations between UA levels and 90-day stroke outcome in patients with and without edaravone treatment.

RESULTS

The high UA group had a higher proportion of men, hypertension, atrial fibrillation, and cardioembolic stroke than the low UA group. The high UA group also had a higher proportion of patients with mRS <2 at 90 days (61.5 vs. 54.1%, p = 0.013), but the significance was diminished in multivariate analysis (OR 1.30, 95% CI 0.94-1.71). In subgroup analysis, the high UA group without edaravone exhibited a higher proportion of patients with mRS <2 at 90 days than the low UA group (OR 2.87, 95% CI 1.20-7.16). The high UA group with edaravone did not exhibit this difference.

CONCLUSIONS

In acute ischemic stroke, the favorable association between high UA levels and outcome at 90 days was not evident in patients treated with edaravone.

Hyperuricaemia as a prognostic factor for acute ischaemic stroke

INTRODUCTION

Recent studies on uric acid as a biomarker for the prognosis of acute stroke have found conflicting results.

METHODS

We collected blood samples from 600 consecutively admitted patients at our tertiary hospital and analysed the relationship between uric acid levels and functional prognosis (measured using the modified Rankin Scale [mRS]). Patients who had received reperfusion therapy were excluded since this may have influenced uric acid levels.

RESULTS

A total of 73% of patients had mRS scores ≤2; the mean uric acid level was 5.22mg/dL. We found a nonlinear relationship between functional prognosis at discharge and serum uric acid levels at admission when the National Institutes of Health Stroke Scale score was excluded from the analysis.

CONCLUSIONS

Serum uric acid levels in patients with acute ischaemic stroke are significantly associated with functional prognosis at discharge, although this relationship is nonlinear. In fact, poorer prognosis is associated both with very low and with very high concentrations of uric acid. This suggests a dual role of uric acid in relation to stroke: on the one hand, as an associated risk factor, and on the other, as a possible neuroprotective factor due to its antioxidant effect.

Free Radical Damage in Ischemia-Reperfusion Injury: An Obstacle in Acute Ischemic Stroke after Revascularization Therapy

Acute ischemic stroke is a common cause of morbidity and mortality worldwide. Thrombolysis with recombinant tissue plasminogen activator and endovascular thrombectomy are the main revascularization therapies for acute ischemic stroke. However, ischemia-reperfusion injury after revascularization therapy can result in worsening outcomes. Among all possible pathological mechanisms of ischemia-reperfusion injury, free radical damage (mainly oxidative/nitrosative stress injury) has been found to play a key role in the process. Free radicals lead to protein dysfunction, DNA damage, and lipid peroxidation, resulting in cell death. Additionally, free radical damage has a strong connection with inducing hemorrhagic transformation and cerebral edema, which are the major complications of revascularization therapy, and mainly influencing neurological outcomes due to the disruption of the blood-brain barrier. In order to get a better clinical prognosis, more and more studies focus on the pharmaceutical and nonpharmaceutical neuroprotective therapies against free radical damage. This review discusses the pathological mechanisms of free radicals in ischemia-reperfusion injury and adjunctive neuroprotective therapies combined with revascularization therapy against free radical damage.

Baicalin Attenuates Blood-Brain Barrier Disruption and Hemorrhagic Transformation and Improves Neurological Outcome in Ischemic Stroke Rats with Delayed t-PA Treatment: Involvement of ONOO--MMP-9 Pathway

Tissue plasminogen activator (t-PA) has a restrictive therapeutic window within 4.5 h after ischemic stroke with the risk of hemorrhagic transformation (HT) and neurotoxicity when it is used beyond the time window. In the present study, we tested the hypothesis that baicalin, an active compound of medicinal plant, could attenuate HT in cerebral ischemia stroke with delayed t-PA treatment. Male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 4.5 h and then continuously received t-PA infusion (10 mg/kg) for 0.5 h and followed by 19-h reperfusion. Baicalin (50, 100, 150 mg/kg) was administrated via femoral vein at 4.5 h after MCAO cerebral ischemia. Delayed t-PA infusion significantly increased the mortality rate, induced HT, blood-brain barrier (BBB) damage, and apoptotic cell death in the ischemic brains and exacerbated neurological outcomes in cerebral ischemia-reperfusion rats at 24 h after MCAO cerebral ischemia. Co-treatment of baicalin significantly reduced the mortality rates, ameliorated the t-PA-mediated BBB disruption and HT. Furthermore, baicalin showed to directly scavenge peroxynitrite and inhibit MMP-9 expression and activity in the ischemic brains with the delayed t-PA treatment. Baicalin had no effect on the t-PA fibrinolytic function indicated by t-PA activity assay. Taken together, baicalin could attenuate t-PA-mediated HT and improve the outcomes of ischemic stroke treatment possibly via inhibiting peroxynitrite-mediated MMP-9 activation.

Sex-specific Association Between Uric Acid and Outcomes After Acute Ischemic Stroke: A Prospective Study from CATIS Trial

The relationship between serum uric acid (UA) and outcomes after acute ischemic stroke remains debatable in human studies, and the sex effect on this association has yet to be explored. Here, we investigated these associations in a prospective study from the China Antihypertensive Trial in Acute Ischemic Stroke. Baseline UA levels were measured in 3284 acute ischemic stroke patients. Primary outcome was defined as a combination of death and major disability (modified Rankin Scale score ≥3) at 3 months. UA levels were significantly higher in men than women (310.6 ± 96.1 vs 257.5 ± 89.9 μmol/L, P < 0.001). The association between serum UA and the primary outcome was appreciably modified by sex (P-interaction = 0.007). After multivariate adjustment, a high serum UA was associated with a decreased risk of primary outcome in men [odds ratio (OR), 0.63; 95% confidence interval (CI), 0.44-0.91; P-trend = 0.01] but not in women (OR, 1.29; 95% CI, 0.83-2.01; P-trend = 0.15), when two extreme quartiles were compared. Subgroup and sensitivity analyses further confirmed these sex-specific findings. Our study indicated that there was a sex-specific association between serum UA and prognosis of acute ischemic stroke. Elevated serum UA was positively associated with better prognosis in men, but not in women.

Serum Uric Acid Levels and Outcomes After Acute Ischemic Stroke

Previous studies assessing the association between serum uric acid levels and neurological outcome after acute ischemic stroke reported conflicting results. A systematic review and meta-analysis were conducted to assess the impact of serum uric acid levels on outcome after acute ischemic stroke. Pubmed, Embase, Web of Science, and Google scholar were searched through September 26, 2014 to identify eligible published or unpublished studies on the association between serum uric acid levels and outcome after acute ischemic stroke. Hazard ratio (HR) for poor outcome or mean differences of serum uric acid levels with 95% confidence intervals (95% CIs) were pooled using meta-analysis. The primary outcome was occurrence of poor outcomes, while the secondary outcome was the mean differences of serum uric acid levels in patients with good or poor outcomes. Ten eligible studies with a total of 8131 acute ischemic stroke patients were included into the meta-analysis. Compared with low serum uric acid level, high serum uric acid level was associated better outcome after acute ischemic stroke (HR = 0.77, 95% CI 0.68-0.88, P = 0.0001). Sensitivity analysis further identified the prognostic role of serum uric acid levels on outcome after acute ischemic stroke. Patients with good outcomes had a higher serum uric acid level compared with those with poor outcome (mean difference = 30.61 μmol/L, 95% CI 20.13-41.08, P < 0.00001). There was no obvious risk of publication bias in the meta-analysis. This meta-analysis supports that serum uric acid level has a protective effect on neurological outcome after acute ischemic stroke. High uric acid level at the onset is a biomarker of better prognosis in patients with acute ischemic stroke.

Depletion of Uric Acid Due to SLC22A12 (URAT1) Loss-of-Function Mutation Causes Endothelial Dysfunction in Hypouricemia

BACKGROUND

Uric acid (UA) serves as an antioxidant in vascular endothelial cells. UA transporter 1 (URAT1) encoded by SLC22A12 is expressed in the kidney and vessels and its loss of function causes hypouricemia. The purpose of this study was to examine whether there is any endothelial dysfunction in patients with hypouricemia.

METHODS AND RESULTS

Twenty-six patients with hypouricemia (<2.5 mg/dl) and 13 healthy control subjects were enrolled. Endothelial function was evaluated using flow-mediated dilation (FMD). mRNA of UA transporters expressed in cultured human umbilical endothelial cells (HUVEC) was detected on RT-PCR. There was a positive correlation between FMD and serum UA in the hypouricemia group. URAT1 loss-of-function mutations were found in the genome of 21 of 26 patients with hypouricemia, and not in the other 5. In the hypouricemia groups, serum UA in homozygous and compound heterozygous patients was significantly lower than in other groups, suggesting that severity of URAT1 dysfunction may influence the severity of hypouricemia. Thirteen of 16 hypouricemia subjects with homozygous and compound heterozygote mutations had SUA <0.8 mg/dl and their FMD was lower than in other groups. HUVEC do not express mRNA of URAT1, suggesting the null role of URAT1 in endothelial function.

CONCLUSIONS

Depletion of UA due to SLC22A12/URAT1 loss-of-function mutations causes endothelial dysfunction in hypouricemia patients.