Serum uric acid as an independent predictor of early death after acute stroke

The association between hyperuricemia, left atrial size and new-onset atrial fibrillation

BACKGROUND

Although hyperuricemia was associated with several cardiovascular diseases, the role of uric acid (UA) in left atrial (LA) remodeling and new-onset atrial fibrillation (AF) has not been fully explored. The goal of the present study is to investigate the relationship between UA, LA diameter and the development of AF in the large-scale cohort.

METHODS

The study consisted of 2 parts. First, we investigated the association between serum UA and LA diameter in a single-center database (n = 3043). Second, we studied and compared the risk of new-onset AF among patients with and without hyperuricemia in the nationwide longitudinal cohort in Taiwan (n = 122,524).

RESULTS

Elevated serum level of UA was associated with an increased systemic inflammation, and insulin resistance. The LA diameter was significantly correlated with serum UA (r = 0.341, p value < 0.001). The linear correlation between LA dimension and UA level remained significant after the adjustment for clinical, biochemical and echocardiographic variables. In the nationwide cohort, there were 2339 patients (1.9% of the study population) developing AF during the follow-up of 6.3 ± 3.0 years. The AF occurrence rate was higher in patients with hyperuricemia than those without it (2.1% versus 1.7%; p value < 0.001). Hyperuricemia was a significant risk factor of new-onset AF with a hazard ratio of 1.191 (95% confidence interval = 1.098-1.292, p value < 0.001) in the multivariate Cox regression analysis.

CONCLUSIONS

Hyperuricemia was associated with a larger LA size and may be a novel risk factor for the development of AF.

Association between uric acid levels and obstructive sleep apnea syndrome in a large epidemiological sample

INTRODUCTION

Recurrent hypoxia, which is associated with obstructive sleep apnea syndrome (OSAS), leads to an increase in the degradation of adenosine triphosphatase into xanthine, which in turn increases uric acid concentrations.

OBJECTIVE

The current study aimed to determine whether an association exists between OSAS and uric acid levels in the peripheral blood from a representative population of Sao Paulo (Brazil).

METHODS

A population-based survey adopting a probabilistic 3-stage cluster sample of Sao Paulo was used to represent the population according to gender, age, and socioeconomic class. A total of 1,042 volunteers underwent polysomnography recordings for OSAS diagnosis, blood pressure assessment, and biochemical blood analysis, and answered questionnaires.

RESULTS

Uric acid levels were correlated with most important risk factors for OSAS, such as AHI, desaturation time and index, minimum oxyhemoglobin saturation (SpO2), blood pressure, cholesterol, BMI, triglycerides and arousal, and with OSAS itself. Also, uric acid was increased in OSAS volunteers even after controlling for all confounders. Hyperuricemic volunteers presented lower mean and minimum SpO2 and increased desaturation index. Importantly, minimum SpO2 was a significant predictor of uric acid levels, which in turn was considered an independent predictor for OSAS in the binary logistic model. However, a ROC curve analysis for establishing cut-off points for uric acid levels as a biomarker of OSAS revealed moderate sensitivity and specificity.

CONCLUSION

A strong association was found between uric acid levels and OSAS in a representative sample of the population of Sao Paulo. Although they do not qualify for a biomarker alone, uric acid levels may be involved in OSAS severity and should be considered in sleep apnea management in the future.

Statins and cardiovascular outcomes in elderly and younger patients with coronary artery disease: a post hoc analysis of the GREACE study

INTRODUCTION

The effect of cardiovascular disease (CVD) prevention measures aimed at elderly patients requires further evidence. We investigated the effect of statin treatment (targeted to achieve guideline goals) on CVD outcomes in different age groups to determine whether statins are more beneficial in the elderly.

MATERIAL AND METHODS

The primary endpoint of this post hoc analysis of the GREek Atorvastatin and Coronary-heart-disease Evaluation (GREACE) study (n = 1,600 patients with established coronary heart disease (CHD), mean follow-up 3 years) was the absolute and relative CVD event (a composite of death, myocardial infarction, revascularization, unstable angina, heart failure and stroke) risk reduction in age quartiles (each n = 200). Patients on "structured care" with atorvastatin (n = 800) followed up by the university clinic and treated to lipid goal were compared with the corresponding quartiles on "usual care" (n = 800) followed up by specialists or general practitioners of the patient's choice outside the hospital.

RESULTS

In the elderly (mean age 69 ±4 and 70 ±3 years in the "structured" and "usual care", respectively) the absolute CVD event reduction between "structured" and "usual care" was 16.5% (p < 0.0001), while in the younger patients (mean age 51 ±3 years and 52 ±3 years in the "structured" and "usual care", respectively) this was 8.5% (p = 0.016); relative risk reduction (RRR) 60% (p < 0.0001) vs. 42% respectively (p = 0.001). The elderly had higher rates of chronic kidney disease and higher uric acid levels, plus an increased prevalence of diabetes, metabolic syndrome and non-alcoholic fatty liver disease. These factors might contribute to the increased CVD risk in older patients.

CONCLUSIONS

All age groups benefited from statin treatment, but the elderly on "structured care" had a greater absolute and relative CVD risk reduction than the younger patients when compared with the corresponding patients assigned to "usual care". These findings suggest that we should not deprive older patients of CVD prevention treatment and lipid target achievement.

Serum uric acid and outcome after acute ischemic stroke: PREMIER study

BACKGROUND

Current evidence shows that uric acid is a potent antioxidant whose serum concentration increases rapidly after acute ischemic stroke (AIS). Nevertheless, the relationship between serum uric acid (SUA) levels and AIS outcome remains debatable. We aimed to describe the prognostic significance of SUA in AIS.

METHODS

We studied 463 patients (52% men, mean age 68 years, 13% with glomerular filtration rate <60 ml/min at hospital arrival) with AIS pertaining to the multicenter registry PREMIER, who had SUA measurements at hospital presentation. Multivariate models were constructed to analyze the association of SUA with functional outcome as assessed by the modified Rankin scale (mRS) at 30-day, 3-, 6- and 12-month follow-up. A mRS 0-1 was regarded as a very good outcome.

RESULTS

Mean SUA concentration at hospital arrival was 6.1 ± 3.7 mg/dl (362.8 ± 220.0 μmol/l). Compared with cases with higher SUA levels at hospital admission, patients with ≤4.5 mg/dl (≤267.7 μmol/l; the lowest tertile of the sample) had more cases of a very good 30-day outcome (30.5 vs. 18.9%, respectively; p = 0.004). SUA was not associated with mortality or functional dependence (mRS >2) at 30 days, or with any outcome measure at 3, 6 or 12 months poststroke. After adjustment for age, gender, stroke type and severity (NIHSS <9), time since event onset, serum creatinine, hypertension, diabetes and smoking, a SUA ≤4.5 mg/dl (≤267.7 μmol/l) was positively associated with a very good short-term outcome (odds ratio: 1.76, 95% confidence interval: 1.05-2.95; negative predictive value: 81.1%), but not at 3, 6 or 12 months of follow-up. When NIHSS was entered in the multivariate model as a continuous variable, the independent association of SUA with outcome was lost. Compared with cases with higher levels, patients with SUA ≤4.5 mg/dl (≤267.7 μmol/l) were more frequently younger than 55 years, women, with mild strokes, with normal serum creatinine and fewer had hypertension. The time since event onset to hospital arrival was not significantly associated with AIS severity or SUA levels; nevertheless, a nonsignificant tendency was observed for patients with severe strokes and high SUA levels arriving in <24 h.

CONCLUSIONS

A low SUA concentration is modestly associated with a very good short-term outcome. Our findings support the hypothesis that SUA is more a marker of the magnitude of the cerebral infarction than an independent predictor of stroke outcome.

Serum uric acid levels and cerebral microbleeds in patients with acute ischemic stroke

Unlike experimental studies indicating a neuroprotective property of uric acid, clinical studies have shown that elevated levels of uric acid are associated with a risk of ischemic stroke. However, the association of uric acid with cerebral hemorrhage has seldom been tested. We aimed to elucidate the association between uric acid and cerebral microbleeds (CMBs), a hemorrhage-prone cerebral microangiopathy. Seven hundred twenty-four patients with ischemic stroke who were consecutively admitted to our hospital were included in this study. We collected demographic, clinical, and laboratory data, including uric acid level, and examined the presence of CMBs using T2*-weighted gradient-echo MRI. We used logistic regression analysis to examine an independent association between uric acid and CMBs. Two-hundred twenty-six patients had CMBs (31.2%). After adjusting for possible confounders, elevated uric acid was independently associated with the presence of CMBs (the highest quartile vs. lowest quartile, adjusted odd ratio [OR], 1.98; 95% confidence interval [CI], 1.16–3.39). This association retained in patients with deep or infratentorial CMBs (with or without lobar CMBs) but not among those with lobar CMBs. In addition, this association was robust among patients with hypertension (the highest quartile vs. lowest quartile, adjusted OR, 2.74; 95% CI, 1.43–5.24). In contrast, we did not find the association in patients without hypertension. We demonstrated that serum uric acid is independently associated with the presence of CMBs. In particular, the relation between uric acid and CMBs was robust in hypertensive patients.

Lack of association between serum uric acid levels and outcome in acute ischemic stroke

BACKGROUND

The prognostic value of serum uric acid (UA) in acute ischemic stroke is controversial. The aim of this study is to further analyse the relation between UA and outcome after acute ischemic stroke.

METHODS

We analysed UA levels in blood samples collected within 6h of stroke onset from patients included in the placebo arm of the US and Canadian Lubeluzole Ischemic Stroke Study (LUB-INT-9). We compared mean serum UA levels in patients with and without early neurological improvement (≥ 4 versus <4 points improvement on NIHSS after 5 days) and in patients with good functional and poor functional outcome (mRS 0-2 versus mRS 3-6). Multivariable logistic regression analyses were performed to adjust for possible confounders.

RESULTS

UA levels of 226 patients were available for analysis. Mean serum UA levels were not significantly higher in patients with than without early neurological improvement (0.33 mmol/L versus 0.30 mmol/L, p=0.070). The difference between patients with good and patients with poor functional outcome was borderline statistically significant (0.34 mmol/L versus 0.31 mmol/L, p=0.050). After adjustment for confounders, higher serum UA levels were neither associated with early neurological improvement OR (1.30, 95% CI 0.98-1.73, p=0.069), nor with a good functional outcome (OR 1.09, 95% CI 0.72-1.65, p=0.690).

CONCLUSION

We found no association between admission serum UA levels and both short- and long-term outcome in acute ischemic stroke.

High Levels of Serum Uric Acid Predict Severity of Coronary Artery Disease in Patients with Acute Coronary Syndrome

We aimed to elucidate the relation between serum uric acid (SUA) level and severity of coronary artery disease (CAD) in nondiabetic, nonhypertensive patients (n = 246) with acute coronary syndrome (ACS). Severity of CAD was assessed by the Gensini score. One, 2, and 3 or more diseased vessels were identified in 87 (35.4%), 55 (22.4%), and 104 (42.2%) patients, respectively. Patients with hyperuricemia had higher Gensini score, high number of diseased vessels, critical lesions, and total occlusion. Serum uric acid level was significantly associated with number of diseased vessels. Serum uric acid was an independent risk factor for multivessel disease by univariate analysis. High levels of SUA associated with the severity of CAD in nondiabetic, nonhypertensive patients with ACS.

Increased serum levels of uric acid are associated with sudomotor dysfunction in subjects with type 2 diabetes mellitus

The aim of this paper was to assess serum uric acid (SUA) levels in patients with type 2 diabetes mellitus (T2DM) with or without sudomotor dysfunction (evaluated by the Neuropad test). We included 36 T2DM patients with sudomotor dysfunction (group A: mean age 63.1 ± 2.6 years) and 40 age-, gender-, renal function- and T2DM duration-matched patients without sudomotor dysfunction (group B: mean age 62.1 ± 3.1 years). SUA was significantly higher in group A (P < 0.001). There was a significant correlation between SUA and Neuropad time to colour change in both groups (group A: r_s = 0.819, P < 0.001; group B: r_s = 0.774, P < 0.001). There was also a significant positive correlation between SUA and CRP in both groups (group A: r_s = 0.947, P < 0.001; group B: r_s = 0.848, P < 0.001). In conclusion, SUA levels were higher in T2DM patients with sudomotor dysfunction than those without this complication. The potential role of SUA in sudomotor dysfunction merits further study.

Plasma brain natriuretic peptide predicts death during hospitalization in acute ischaemic stroke and transient ischaemic attack patients with atrial fibrillation

BACKGROUND AND PURPOSE

atrial fibrillation (AF) is the most powerful predictor of early death in patients with acute ischaemic stroke. We investigated whether the plasma brain natriuretic peptide (BNP) level on admission can serve as a biological marker of in-hospital death in acute ischaemic stroke and transient ischaemic attack (TIA) patients with AF.

METHODS

we prospectively enrolled ischaemic stroke and TIA patients with AF within 24 h of onset and measured plasma BNP on admission. Patients were divided into two groups: the deceased group, who died during hospitalization, and the survival group. The factors associated with in-hospital death were investigated by multivariate logistic regression analysis.

RESULTS

a total of 221 patients with AF were enrolled. Death occurred in 24 (10.9%) patients. The mean ± SD of the plasma BNP level of the deceased group was significantly higher than that of the survival group (714.1 ± 716.3 vs. 320.0 ± 380.7 pg/ml, P < 0.0001). The optimal cutoff level, sensitivity, and specificity of BNP levels to distinguish the deceased group from the survival group were 320 pg/ml, 79.2, and 69.0%, respectively. Multivariate logistic regression analysis demonstrated that age per 10 years increase (OR, 3.56; 95% CI, 1.728-7.346, P = 0.0006), internal carotid artery occlusion (OR, 10.20; 95% CI, 2.525-41.177, P = 0.0011), NIHSS score of >17 (OR, 4.68; 95% CI, 1.137-19.286, P = 0.0325), and plasma BNP level of > 320 pg/ml (OR, 4.74; 95% CI, 1.260-17.800, P = 0.0213) were independent factors associated with in-hospital death.

CONCLUSION

the plasma BNP level on admission can predict in-hospital death in acute ischaemic stroke and TIA patients with AF.

Prevalence of Metabolic Syndrome According to Different Definitions in a Hypertensive Population

Aims: The metabolic syndrome (MetS) is associated with increased risk of cardiovascular disease (CVD) and diabetes mellitus (DM). Several definitions of MetS have been proposed. The aim of the present study was to estimate and compare the prevalence of MetS according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III), American Heart Association-National Heart Lung and Blood Institute (AHA-NHLBI), International Diabetes Federation (IDF) and the more recent Joint Interim Statement (JIS) definitions in patients attending a hypertension clinic. Methods: The records of patients referred to the hypertension clinic at the University Hospital (Heraklion, Crete) from January 2001 to June 2009 were screened retrospectively. A total 384 patients (146 men) were included in the study. Results: The prevalence of MetS according to the IDF and JIS definitions was significantly higher compared with that of the NCEP ATP III in both genders (IDF: P = .009 and P = .002, JIS: P = .002 and P = 0.001 for men and women, respectively); this was the case for the AHA-NHLBI definition only among women ( P = .03). All MetS components differed significantly ( P from < .0001 to .02) between patients with and without MetS for all definitions. Conclusions: The prevalence of MetS varies considerably depending on the definition used in a hypertensive population in a Mediterranean country. These differences will influence risk assessment.

Peripheral neuropathy is associated with increased serum levels of uric acid in type 2 diabetes mellitus

We assessed serum uric acid (SUA) levels in patients with type 2 diabetes mellitus (T2DM) with or without peripheral neuropathy (diagnosed by the Neuropathy Disability score [NDS]). We enrolled 64 patients with T2DM with peripheral neuropathy (group A: 31 men, mean age 63.0 ± 2.8 years) and 66 age-, gender-, renal function- and T2DM duration-matched patients without neuropathy (group B: 32 men, mean age 62.4 ± 3.1 years). Serum uric acid was significantly higher in group A (P < .001). There was a significant correlation between SUA and NDS in both groups (group A: r(s) = .93, P < .001; group B: r( s) = .95, P < .001). C-reactive protein (CRP) was also significantly higher in group A (P < .001) and correlated significantly with SUA in both groups (group A: r(s) = .93, P < .001; group B: r(s) = .87, P < .001). Serum uric acid is increased in patients with T2DM with neuropathy versus those without. Whether SUA is involved in the pathogenesis of T2DM peripheral neuropathy remains to be established.

Retrospective analysis of the predictive effect of routine biochemical results on the prognosis of intracerebral hemorrhage

OBJECTIVE

To find the effective biochemical factors for predicting the outcome of acute intracerebral hemorrhage (ICH).

METHODS

According to the outcome, 497 ICH patients were divided into two groups (effective treatment group, ineffective treatment group). The routine biochemical results were analyzed between groups with SPSS software 13.0, including TC, TG, HDL-c, LDL-c, UA, and Glu. The differences of these items were found by independent sample T test and Kruskal-Wallis test between groups. Then the items, which were significantly associated with the prognosis of ICH patients, were obtained by the logistic regression. In addition, we calculated the odds ratio (OR) for the special indicators by chi-square test.

RESULTS

Only UA, Glu, and HDL-c had significant differences between groups (P<0.05) among the six biochemical items. The binary logistic regression analysis indicated that high Glu and UA were related to the outcome of ICH (P<0.01). By chi-square test, the OR of high Glu was 3.95 (2.27-6.87 with 95% CI) and that of high UA was 2.19 (1.16-4.11 with 95% CI), but HDL-c's OR was only 0.90 (0.41-1.98 with 95% CI) without statistical significance.

CONCLUSION

High Glu and UA were risk factors for the prognosis of ICH; monitoring and controlling the Glu and UA may be advisable improving the prognosis of ICH.

Decrease in uric acid in acute ischemic stroke correlates with stroke severity, evolution and outcome

BACKGROUND

Although uric acid (UA) is one of the most important antioxidants in plasma and appears to be neuroprotective in animal models, results from human studies are controversial. In this study, we investigated the kinetics of serum UA concentrations in the acute, subacute and chronic phase of ischemic stroke and its relation with initial stroke severity, stroke evolution in the subacute phase and long-term stroke outcome.

METHODS

Serum concentrations of UA were measured in 199 stroke patients at admission (median, 2.8 h after stroke onset), at 24 h, 72 h, day 7, month 1 and month 3 after onset of stroke. We evaluated the relationship between changes in UA concentrations and (a) stroke severity [patients with transient ischemic attack (TIA) vs. stroke patients, National Institutes of Health Stroke Scale (NIHSS) score at admission], (b) stroke evolution (stroke progression, infarct volume at 72 h), and (c) stroke outcome [modified Rankin scale (mRS) score at month 3, mortality].

RESULTS

UA concentrations decreased significantly during the first 7 days after stroke onset before returning to baseline (p < 0.001). Mean plasma UA concentrations decreased from 336.66 +/- 113.01 micromol/L at admission to 300.37 +/- 110.04 micromol/L at day 7 (p < 0.001) in patients with stroke, but did not change significantly in patients with TIA. Changes in UA concentrations from admission to day 7 (DeltaUA(day 7)) correlated with the NIHSS score (rho = 0.32; p < 0.001), stroke progression (rho = 0.29; p = 0.001), infarct volume (rho = 0.37; p < 0.001), mRS score (rho = 0.28; p = 0.001) and mortality (p = 0.010).

CONCLUSIONS

Decreases in UA during the first week after onset of stroke correlates with more severe stroke, unfavorable stroke evolution, and poor long-term stroke outcome.

Seasonal variation in the occurrence of stroke in Northern Greece: a 10 year study in 8204 patients

OBJECTIVE

The effect of seasonal variation on the occurrence of stroke remains controversial. The objective of this study was to determine whether there is a seasonal variation in the occurrence of stroke in Northern Greece.

METHODS

We recorded the seasonal stroke rates over a 10 year period (from January 1997 to December 2006) in 8204 patients in Northern Greece. The findings were analysed separately for ischemic stroke (IS), intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH) and transient ischemic attack (TIA).

RESULTS

In patients with IS, there was a significant seasonal variation (p<0.001), with the peak incidence in spring (8.4% above average) and the lowest rate in summer (10.4% below average). There was no significant seasonal variation in the occurrence of the other stroke subtypes (ICH, SAH and TIA) when they were considered individually.

DISCUSSION

The seasonal effect on stroke incidence needs to be defined so as to improve the provision of preventive measures.

Higher serum uric acid on admission is associated with higher short-term mortality and poorer long-term survival after myocardial infarction: retrospective prognostic study

AIM

To assess serum uric acid (SUA) levels determined on admission as a potential predictor of short-term mortality and long-term survival in acute myocardial infarction (AMI) patients.

METHOD

Data for this retrospective prognostic study were drawn from the patient database of the Varazdin County General Hospital in Varazdin, Croatia. We included consecutive patients with verified AMI admitted within 48 hours since the symptom onset during the period between 1 January 1996 and 31 December 2001. Long-term survival/mortality data were collected through direct contacts with patients and search of the community death registries. Relative risks (RR) and hazard ratios (HR) by 10 micromol/L increase in SUA were determined using modified Poisson regression with robust error variance and proportional hazard regression, respectively.

RESULTS

A total of 621 patients (age 27-90 years, 64.7% men, 77.5% AMI with ST elevation, SUA 63-993 micromol/L) were included. Higher SUA on admission was independently associated with higher in-hospital mortality (RR, 1.016; 95% confidence interval [CI], 1.001-1.031, P=0.043) and higher thirty-day mortality (RR, 1.016; 95% CI, 1.003-1.029, P=0.018). Considered covariates were demographics, pre-index event cardiovascular morbidity and treatment, on-admission serum creatinine, total cholesterol and triglycerides, AMI characteristics, and peak creatine phosphokinase. Higher SUA on admission was also independently associated with poorer long-term survival (ie, higher all-cause mortality) (HR, 1.105; 95% CI, 1.020-1.195, P=0.010). Considered covariates were demographics, laboratory variables on admission, AMI characteristics, peak creatine phosphokinase, acute complications, and treatment at discharge.

CONCLUSION

Higher serum uric acid determined on admission is associated with higher in-hospital mortality and thirty-day mortality and poorer long-term survival after AMI.

The potential for xanthine oxidase inhibition in the prevention and treatment of cardiovascular and cerebrovascular disease

There is a now a wealth of epidemiological, animal, and clinical data to suggest the benefits of uric acid reduction and hxanthine oxidase inhibition in prevention of vascular disease. This review discusses the available epidemiological, preclinical, and clinical data and considers arguments for and against a role for serum uric acid in common cardiovascular disorders. It concludes that large scale trials with clinical endpoints are justified to address this important question and to define whether use of drugs such as allopurinol should be a routine part of preventative strategies.

Clinical review: The pathogenetic role of cortisol in the metabolic syndrome: a hypothesis

CONTEXT

The metabolic syndrome (MetS) is a cluster of metabolic abnormalities that increase the risk for type 2 diabetes mellitus and vascular disease. The common characteristics of MetS and hypercortisolemic conditions such as Cushing's syndrome (CS) suggest that the pathogenesis of MetS and central obesity might involve prolonged and excessive exposure to glucocorticoids. The present review summarizes the evidence on the potential role of cortisol in the pathogenesis of MetS and discusses new therapeutic approaches for these patients.

EVIDENCE ACQUISITION

Using PubMed, we searched for publications during the last 20 yr regarding the possible pathogenetic role of cortisol in the development of MetS.

EVIDENCE SYNTHESIS

Emerging data suggest that patients with MetS show hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, which leads to a state of "functional hypercortisolism." The cause for this activation of the HPA axis remains uncertain but may be partly associated with chronic stress and/or low birth weight, which are both associated with increased circulating cortisol levels and greater responsiveness of the HPA axis. Increased exposure to cortisol contributes to increased fat accumulation in visceral depots. However, cortisol metabolism is not only centrally regulated. The action of 11beta-hydroxysteroid dehydrogenase-1 at the tissue level also modulates cortisol metabolism. Increased 11beta-hydroxysteroid dehydrogenase-1 activity in adipose tissue and liver might contribute to the development of several features of the MetS.

CONCLUSIONS

MetS shares many characteristics of CS, and cortisol might play a role in the development of MetS at both a central and a peripheral level.

Diabetes mellitus and cerebrovascular disease: which are the actual data?

Cerebrovascular disease (CeVD) represents a major cause of morbidity and mortality worldwide. Diabetes mellitus (DM) represents an independent risk factor for CeVD. The aim of the present review is to describe the epidemiology of CeVD in patients with DM and to explain how DM and diabetic autonomic neuropathy can increase the risk of CeVD. The prevention and management of CeVD in the diabetic population are also analyzed.

Uric acid and dementia in community-dwelling older persons

BACKGROUND

The biological action of uric acid (UA) in humans is controversial. UA is considered an antioxidant compound, but preclinical evidence suggests a proinflammatory action. Epidemiological studies found that hyperuricemia is associated with conditions leading to dementia. Our aim is to investigate the relationship between UA levels and dementia in older persons.

METHODS

Cross-sectional study performed in 1,016 community-dwelling older persons participating in the InCHIANTI study. Participants underwent determination of circulating UA levels and neuropsychological evaluation. A multivariate logistic regression model was used to estimate the probability of participants belonging to the highest and middle UA tertile to be affected by dementia compared to those in the lowest tertile.

RESULTS

Demented persons had higher UA levels (p = 0.001) and the prevalence of persons affected by dementia increased across UA tertiles (p < 0.0001). Independent of several confounders, persons belonging to the highest UA tertile had a threefold (OR = 3.32; 95% CI: 1.06-10.42) higher probability to suffer from a dementia syndrome while those in the middle UA tertile tended to have a higher probability of being demented compared to those in the lowest tertile.

CONCLUSION

In a population-based sample, high circulating UA levels are associated with an increased likelihood to be affected by a dementia syndrome.

Uric acid and left ventricular hypertrophy in Japanese men

BACKGROUND

Experimental studies have reported that allopurinol protects hypertensive rats from left ventricular hypertrophy (LVH) with negligible effects on blood pressure (BP). Uric acid (UA) was thought to induce cardiomyocyte growth and interstitial fibrosis of the heart, partly via activation of the renin-angiotensin system. In the present study, the relationship between serum UA levels and electrocardiographically-diagnosed LVH (ECG-LVH) was examined in Japanese men not taking medication for hypertension (HTN), which could confound the association.

METHODS AND RESULTS

A total of 3,305 male workers aged 35-66 years (mean age+/-SD, 48.0+/-7.1) were studied. LVH was defined as meeting the ECG criteria (ie, Sokolow-Lyon voltage and/or Cornell voltage QRS duration product). Subjects were divided into 3 groups by tertile of serum UA level. The highest tertile (UA range 0.39-0.65 mmol/L or 6.6-11.0 mg/dl) had a significantly increased prevalence of LVH compared with the lowest tertile independent of age, body mass index, serum creatinine level, HTN, diabetes and hyperlipidemia (odds ratio 1.58, 95% confidence interval 1.23-2.02, P<0.001). Similar results were obtained in both the normal and high BP subgroups.

CONCLUSIONS

UA concentration independently and positively associated with ECG-LVH in Japanese men.

Chronic kidney disease and clinical outcome in patients with acute stroke

BACKGROUND AND PURPOSE

Chronic kidney disease (CKD) is increasingly recognized as an independent risk factor for cardiovascular disease and stroke. Our aim was to examine the association between estimated glomerular filtration rate (GFR) and stroke outcome and to assess whether CKD and its severity affect stroke outcome in a large cohort of unselected patients with acute stroke.

METHODS

We examined the association between baseline estimated GFR and CKD and 1-year outcomes in 821 consecutive patients with acute stroke (ischemic or hemorrhagic). GFR was estimated by 2 methods: the Modification of Diet in Renal Disease and the Mayo Clinic quadratic equation. An estimated GFR rate <or=60 mL/min/1.73 m(2) defined CKD.

RESULTS

Odds ratios (95% CI) for death across levels of estimated GFR based on both equations were estimated. CKD was present in 36% (n=291) of patients based on the Modification of Diet in Renal Disease equation and 18% (n=147) based on the Mayo Clinic equation. The adjusted ORs for mortality after 1-year based on the Modification of Diet in Renal Disease equation were 0.7 (95% CI, 0.4 to 1.2) associated with GFR 45 to 60 and 3.2 (1.7 to 6.4) associated with GFR 15 to 44 as compared with GFR >60 mL/min/1.73 m(2), whereas those based on the Mayo Clinic equation were 2.3 (1.1 to 4.7) and 3.3 (1.6 to 7.1), respectively. The adjusted ORs for Barthel Index <or=75 or death after 1 year were 0.8 (0.5 to 1.5) and 2.1 (0.9 to 4.8) by the Modification of Diet in Renal Disease equation and 1.9 (0.8 to 4.4) and 3.9 (1.5 to 11.0) by the Mayo Clinic equation, respectively.

CONCLUSIONS

CKD is a strong independent predictor of mortality and poor outcome in patients with acute stroke. The estimation of the prevalence of CKD and of the GFR cutoffs associated with poor outcome depend on the equation used to estimate GFR.

Plasma brain natriuretic peptide as an independent predictor of in-hospital mortality after acute ischemic stroke

BACKGROUND AND PURPOSE

We investigated whether the plasma brain natriuretic peptide (BNP) level on admission can serve as a biological marker of in-hospital death in patients with acute ischemic stroke.

METHODS

We prospectively enrolled 335 consecutive patients (125 females; mean age, 72.3 years) with acute ischemic stroke within 24 hours of onset and measured plasma BNP on admission. Patients were divided into two groups: the deceased group, who died during hospitalization; and the survival group. The factors associated with in-hospital death were investigated by multivariate logistic regression analysis.

RESULTS

Death was observed in 20 (6.0%) patients. Frequencies of atrial fibrillation, cardioembolism, the use of diuretics before ischemic stroke, the use of digitalis before ischemic stroke, National Institutes of Health Stroke Scale (NIHSS) score on admission, glucose level, and D-dimer were significantly higher in the deceased group than in the survival group. On the other hand, albumin was significantly lower in the deceased group than in the survival group. The mean +/- SD of the plasma BNP level of the deceased group was significantly higher than that of the survival group (731.5+/-1,070.9 vs. 213.1+/-384.5 pg/mL, p=0.001). The optimal cut-off level, sensitivity, and specificity of BNP levels to distinguish the deceased group from the survival group were 240 pg/mL, 75.0% and 73.0%, respectively. Multivariate logistic regression analysis demonstrated that a NIHSS score of >13 (odds ratio [OR], 4.87; 95% confidence interval, 1.54 to 15.44, p=0.007) and plasma BNP level of >240 pg/mL (OR, 4.67; 95% confidence interval, 1.28 to 17.09, p=0.020) were independent factors associated with in-hospital death.

CONCLUSION

The plasma BNP level on admission can predict in-hospital death in patients with acute ischemic stroke.

Role of xanthine oxidoreductase in cardiac nitroso-redox imbalance

Emerging evidence supports the importance of nitroso-redox balance in the cardiovascular system. Xanthine oxidoreductase (XOR) is a major oxidative enzyme and increased XOR activity, leading to both increased production of reactive oxygen species and uric acid, is implicated in heart failure. Within the heart, XOR activity stimulates cardiomyocyte hypertrophy, apoptosis, and impairs matrix structure. The underpinnings of these derangements can be linked not solely to oxidative stress, but may also involve the process of nitroso-redox imbalance. In this regard, XOR interacts with nitric oxide signaling at numerous levels, including a direct protein-protein interaction with neuronal nitric oxide synthase (NOS1) in the sarcoplasmic reticulum. Deficiency or translocation of NOS1 away from this microdomain leads to increased activity of XOR, which in turn impairs excitation-contraction coupling and myofilament calcium sensitivity. There is a mounting abundance of preclinical data supporting beneficial effects of inhibiting XOR, but translation to the clinic continues to be incomplete. A growing understanding of XOR and its role in nitroso-redox imbalance has great potential to lead to improved pathophysiologic insights and possibly therapeutic advances.

The role of uric acid in stroke: the issue remains unresolved

BACKGROUND

Although in the past decade a large number of studies have been performed to identify the relationship between uric acid and stroke, the issue remains unresolved and it is not clear whether the correlation between uric acid and stroke is circumstantial or causal.

REVIEW SUMMARY

Some studies have found uric acid predictive for the development of cardiovascular disease, whereas others have failed to identify uric acid as a significant and independent risk factor after controlling for other atherosclerotic risk factors. Furthermore, uric acid, a powerful endogenous antioxidant, is increased in oxidative stress situations such as stroke. Still, it remains controversial whether elevated serum uric acid is neuroprotective or injurious at the onset of acute stroke.

CONCLUSIONS

Large trials are required to provide definite answers in clinical practice and to reevaluate the goals of hypouricemic treatment in subjects with increased cardiovascular risk or during an acute cardiovascular event like stroke. This review tries to keep pace with the data concerning the association between uric acid and stroke.

Association of serum bilirubin with ischemic stroke outcomes

BACKGROUND

Higher levels of serum bilirubin may offer a therapeutic advantage in oxidative stress-mediated diseases, but may also simply reflect intensity of oxidative stress. Little is known about the role of bilirubin in stroke. We assessed the relation of serum bilirubin levels with clinical presentation and outcomes among patients hospitalized with ischemic stroke.

METHODS

Data were collected prospectively during a 5-year period on consecutive ischemic stroke admissions to a university hospital. Serum bilirubin levels, total (Tbil) and direct (Dbil), were measured on admission. Presenting stroke severity was assessed with the National Institutes of Health Stroke Scale (NIHSS). Functional outcome at discharge was assessed using the modified Rankin scale.

RESULTS

Among 743 patients, mean age was 67.3 years and 47.5% were women. Median presenting NIHSS score was 4, and 24% had a poor (modified Rankin scale 4-6) functional outcome at discharge. Higher Dbil levels were associated with greater stroke severity (P = .001) and poorer discharge outcome (P = .034). Multivariable regression analyses showed that those with higher Dbil levels (> or =0.4 mg/dL) had significantly greater admission NIHSS scores compared with those with lower levels (< or =0.1 mg/dL) (odds ratio 2.79, 95% confidence interval 1.25-6.20, P = .012), but no independent relationship was confirmed between Dbil and discharge outcome. Although higher admission Tbil was associated with greater stroke severity in crude analyses (P = .003), no independent relationship between Tbil versus stroke severity or outcome was noted after adjusting for confounders.

CONCLUSIONS

Higher Dbil level is associated with greater stroke severity but not outcome among ischemic stroke patients, possibly reflecting the intensity of initial oxidative stress. Further study into the underlying pathophysiology of this relationship is needed.

Uric acid administration in patients with acute stroke: a novel approach to neuroprotection

Uric acid (UA) is the end product of purine catabolism in humans and is a powerful antioxidant whose generation is increased under ischemic conditions. However, both clinical and experimental studies reveal a gradual exhaustion of the antioxidant capacity after transient cerebral ischemia, and the magnitude of this consumption seems to be correlated with the extent of brain tissue injury, growth of the infarction, severity of neurological impairment in the acute phase, and long-term functional outcome. Growing evidence supports the neuroprotective effect of UA administration after brain ischemia. In experimental conditions, the administration of UA is neuroprotective both in mechanical models of brain ischemia (transient or permanent intraluminal occlusion of the middle cerebral artery) and in thromboembolic models of autologous clot injection. The administration of UA is feasible and safe in healthy volunteers. In acute stroke patients treated with recombinant tissue plasminogen activator (rt-PA), co-administration of UA has proven to reduce lipid peroxidation and to prevent the fall in UA blood levels that occur very early after stroke onset. Currently, a multicentric Phase III clinical trial is testing whether the administration of UA increases the clinical benefits of rt-PA, which represents the only approved therapy in patients with acute ischemic stroke. This review summarizes the available information justifying such a novel therapeutic approach in this devastating clinical condition.