Serum Uric Acid Level And Its Effects On Short-term Outcome In Acute Ischemic Stroke

Objective: Uric acid (UA) is the final product of purine metabolism ofhuman endogenous and exogenous purine on the effect of xanthine oxidase inhumans, and is excreted in urine, which is associated with various risk factorsfor cerebrovascular disease tightly as a marker of metabolic disorders.Normally, the excretion of uric acid produced in the body can substantiallymaintain homeostasis per day. It can cause hyeruricemia (HUA) when purinegenerated excessively or uric acid disposaled too little via the kidneys. It iswell known that HUA is related to many aspects of the metabolic syndrome(MS), such as hypertension, lipid metabolism disorders, high blood glucose,heart disease, obesity and insulin resistance, HUA can cause the initiation anddevelopment of atherosclerosis through multiple mechanisms. Numerousstudies show that hyperuricemia may be associated with increased incidencesof ischemic stroke, poor prognosis and early death as a new risk factor ofcerebrovascular disease. There are also studies suggest that UA may exhibitsneuroprotective effects on acute ischemic stroke as an effective antioxidantand free radical scavenger, which can improve the stroke outcomes and reducestroke recurrence. However, the role of serum uric acid in ischemic cerebralstroke remains controversial. Therefore, this study aims to observe the level ofserum uric acid in the acute phase of ischemic stroke, and to evaluate therelationship between the level of serum uric acid and the short-term strokeoutcome with a method of large sample and retrospective analysis.Methods：This is a retrospective study involving1085acute ischemicstroke patients who met the inclusion criteria admitted by the Department ofneurology, the Third Hospital of Hebei Medical University from March,2012to September,2013, and the involved patients were enrolled a clear diagnosis of the cause of large artery atherosclerosis (LAA) group and small arteryocclusion (SAO) group according to classic TOAST subtype. All patients havedetailed clinical information including demographic composition, history ofvascular risk factors, family history, skull structure imaging and vascularimaging studies such as Transcranial Doppler ultrasound, carotid ultrasound,blood tests and the results of the baseline state of neurological impairment andrecords of disease outcomes. Main exclusion criteria are as follows:(1)clinical data was incomplete, which make it difficult to identify TOASTetiology type,lack of serum uric acid test results, as well as the patients ofcardio embolism, acute stroke of other determined etiology, and Stroke ofother undetermined etiology;(2) difficulty to assess the condition due to thelegacy of previous disease sequelae;(3) history of gout;(4) severe cardiacfunctional insufficiency, hepaticin sufficiency, renal insufficiency(chronicnephritis, hypertensive nephropathy, diabetic nephropathy);(5) mental illness;(6) hypertensive crisis, hypertensive encephalopathy;(7) intake of drugs thatmay increase UA levels, such as thiazide diuretics. All patients werehospitalized within7days after onset, and the average length of stay was14days. It according to clinical examination findings of admission, discharge toscore when patients with no original case NIHSS score record. Poorshort-term outcome criteria:(1) Death during hospitalization;(2) theneurological examination was assessed with the National Institutes of HealthStroke Scale (NIHSS) by neurologists certified, and stroke worsening requiredat least a4-point change in the NIHSS score, namely (admission NIHSS score-at discharge NIHSS score) Rating/admission NIHSS <40%. Analyses wereperformed by SPSS16.0for Windows. Count data with positive cases,proportion said, using χ2test. Measurement data were presented as mean±standard deviation, using t test. Logistic regression analysis was used inmultivariate analysis. P<0.05was considered as statistically significantjudgment. The incidence of hyperuricemia in different types of stroke patientswas compared; with demographic situation, the TOAST classification,hypertension, diabetes, hyperlipidemia, coronary heart disease, family history of cardiovascular disease, uric acid, serum urea, serum creatinine andhemoglobin levels of all the patients as independent variables, andmultivariate Logistic regression models were respectively performed with theunivariate analysis which were statistically significant indicators, to determinethe independent risk factors of HUA and the the correlation of short pooroutcome in patients with acute cerebral infarction.Results：1.1085patients met the inclusion criteria were included in thisstudy. The whole sample consisted of709male cases (65.35%),376femalecases(36.45%); LAA, SAO patients were747cases (68.85%),338cases(31.15%) repectively; according to the percentage of NIHSS score decreasedof discharged patients and the baseline score,346cases (31.89%) weredeterminated as poor outcome,10cases of which died during hospitalization,and739cases of patients were with good outcome (61.11%).11.15%strokepatients were found with HUA,14.46%LAA patients are associated withHUA, which is much higher than that of SAO patients, which is3.85%(χ2=22.866, OR=4.225, P=0.000),1.29%patients were with low level of serumuric acid, overall incidence of abnormal level of SUA was12.44%.14.74%poor short-term outcome patients associated with HUA, low serum level ofuric acid patients accounted for2.02%, abnormal level of uric acid was16.76%in patients of poor short-term outcome.2. With HUA as the dependentvariable, and with cerebrovascular disease risk factors such as hypertension,diabetes, hyperlipidemia as independent variables, which showed that in thesingle factor Logistic regression analysis: hypertension, hyperlipidemia,increased urea values, increased creatinine values were the risk factors ofHUA. Nevertheless, it has no significant correlation between the gender, age,smoking, alcohol consumption, diabetes, heart disease, family history ofcardiovascular disease, low hemoglobin and the HUA. After adjusting for age,gender and other factors, multivariable logistic regression identified increasedcreatinine values (OR=5.767,95%CI:3.101~10.723, P=0.000), LAA (OR=4.332,95%CI:2.356~7.966, P=0.000), increased urea values (OR=2.307,95%CI:1.283~4.148, P=0.005), hyperlipidemia (OR=2.017,95%CI:1.307~ 3.112, P=0.002) increased the risk of HUA, as an independent risk factor ofHUA.3. With the functional deficit nerve of short-term discharged patients asdependent variable, to evaluate the risk factors of poor short-term outcome inacute ischemic stroke patients. With the risk factors of cerebrovascular diseasesuch as hypertension, diabetes, hyperlipidemia as independent variables,univariate analysis identified HUA (χ2=6.502, OR=1.652, P=0.011), abnormallevel of uric acid (χ2=8.558, OR=1.731, P=0.003), hypertension, diabetes,increased urea values increased the risk of poor short-term outcome in patientswith acute ischemic stroke. However, the gender, age, LAA, smoking,hyperlipidemia, heart disease, family history of cardiovascular disease,increased creatinine values and low hemoglobin all had no significantcorrelation with short-term poor outcome in acute ischemic stroke patients.Multivariable logistic regression identified HUA (OR=1.448,95%CI:0.967~2.168, P=0.072) had no correlation with poor short-term outcome in acuteischemic stroke patients. Whereas, increased urea values (OR=1.748,95%CI:1.107~2.760, P=0.017), hypertension (OR=1.635,95%CI:1.183~2.260, P=0.003), abnormal level of uric acid (OR=1.515,95%CI:1.031~2.225, P=0.034), diabetes (OR=1.362,95%CI:1.037~1.790, P=0.026) wereindependent risk factors for the poor short-term outcome of acute ischemicstroke patients.Conclusion：HUA is more likely to occur in patients with LAA andhyperlipidemia. Abnormal level of SUA is an independent risk factor of poorshort-term outcome of ischemic stroke and HUA is only a warning factor ofpoor short-term outcome in acute ischemic stroke patients.