Fatty Liver and Uric Acid Levels Predict Incident Coronary Heart Disease but Not Stroke among Atomic Bomb Survivors in Nagasaki

Hyperuricemia as an effect modifier of the association between metabolic phenotypes and nonalcoholic fatty liver disease in Chinese population

BACKGROUND

Different metabolic phenotypes may be related to nonalcoholic fatty liver disease (NAFLD), but such association whether modified by serum uric acid levels is unknown. We examined the association between different metabolic phenotypes and NAFLD and further explore whether hyperuricemia could modify this association.

METHODS

A total of 2959 participants (mean age: 55.02 years) with medical checkups were recruited from Tianjin Medical University General Hospital. Participants were categorized into four groups according to their BMI levels and metabolically healthy status: metabolically healthy normal weight (MHNW), metabolically healthy overweight or obese (MHO), metabolically unhealthy normal weight (MUNW), and metabolically unhealthy overweight or obese (MUO). Blood samples (including serum uric acid) were collected from participants after an overnight fast. NAFLD was diagnosed based on abdominal ultrasonography scanning. Data were analyzed using logistic regression models and the interaction effect model.

RESULTS

The prevalence of NAFLD in MHNW, MHO, MUNW, and MUO groups was 9.9% (7.9-12.0%), 42.8% (39.5-46.1%), 36.5% (31.2-41.9%), and 69.7% (66.8-72.6%), respectively. In multi-adjusted logistic models, the ORs (95% CIs) of NAFLD were 5.32 (4.01-7.04) for participants with MHO, 4.51 (3.17-6.40) for those with MUNW, and 13.68 (10.23-18.30) for those with MUO compared to those with MHNW. In the stratified analysis by uric acid levels, the prevalence of NAFLD was significantly higher in participants with MHO, MUNW, and MUO in the hyperuricemia group than those in the normal uric acid group, and the interaction effect of metabolic phenotypes and uric acid on NAFLD was statistical significant (P < 0.05).

CONCLUSIONS

MHO, MUNW, and MUO were associated with higher prevalence of NAFLD. Serum uric acid levels may modify the association between metabolically phenotypes and NAFLD.

Serum Uric Acid Levels and Nonalcoholic Fatty Liver Disease: A 2-Sample Bidirectional Mendelian Randomization Study

BACKGROUND

Observational studies have shown that nonalcoholic fatty liver disease (NAFLD) is highly correlated with serum uric acid (SUA). However, these studies have an inherent risk of bias due to reverse causality. Here, we perform a Mendelian randomization (MR) study to investigate causality between SUA and NAFLD.

METHODS

We performed a 2-sample bidirectional MR analysis using summary-level data from genome-wide association studies of SUA (with up to 110 347 individuals) and NAFLD (1483 cases and 17781 controls) in European populations. First, 13 single nucleotide polymorphisms (SNPs) associated with SUA were selected as instruments to estimate the causal effect of elevated SUA levels on the risk of NAFLD using the inverse-variance weighted (IVW) method. Then we performed MR with 3 SNPs as genetic instruments for NAFLD. To test the reliability, further sensitivity analyses were also conducted.

RESULTS

Our MR analyses demonstrated that NAFLD was associated with SUA levels (β = 0.032, P = 0.003). Similar results were obtained using other MR methods and in sensitivity analyses. Genetic predisposition to elevated SUA levels was not associated with NAFLD (IVW MR, odds ratio = 1.02, 95% CI: 0.90-1.15, P = 0.775). Similar results were obtained using other 4 pleiotropy robust MR methods and in sensitivity analyses, excluding 9 SNPs associated with potential confounders.

CONCLUSIONS

Our study supports the causal increased SUA levels by NAFLD, while our study does not confirm a causal association for SUA levels on risk of NAFLD. Further study is needed to interpret the potential mechanisms.

Serum uric acid and risk of stroke: a dose-response meta-analysis

The relationship between serum uric acid and risk of stroke is still controversial. Therefore, we conducted a meta-analysis based on the cohort study to explore the relationship between serum uric acid and risk of stroke, and further illuminate whether there is a linear or non-linear relationship between them. We manually searched the database including Cochrane, PubMed, Embase, Web of Science, and selected cohort studies focusing on the relationship between serum uric acid and stroke risk. Random effect model was used for statistical analysis. Twenty-one cohort studies involving 818,098 participants were included. The pooled relative risk for the high-vs-low categories was 1.22 (95% CI: 1.15-1.30). In addition, there was a non-linear dose-response relationship between uric acid and stroke risk. Serum uric acid was in the range of 3-5 mg/dl, with the lowest risk of stroke. In conclusion, high serum uric acid level increases the risk of stroke, with a non-linear dose-response relationship.

Higher Serum Uric Acid Level Predicts Non-alcoholic Fatty Liver Disease: A 4-Year Prospective Cohort Study

Background: Non-alcoholic fatty liver disease (NAFLD) has become a serious disease affecting people's health in the world. This article studies the causal relationship between NAFLD and serum uric acid (SUA) levels. Methods: During the 4 years of follow-up in a fixed cohort that was established in 2014, 2,832 follow-up subjects without NAFLD were finally included in this study. The study population was divided into four groups according to baseline SUA levels. Cox hazard regression model and Kaplan-Meier survival curves analysis were used to predict risk factors of NAFLD. The receiver operating characteristic curve analyses were used to determine SUA cutoffs for predicting NAFLD. Results: The cumulative prevalence rates of NAFLD were 33.97% (962/2,832), 38.93% (758/1,947) in males and 23.05% (204/885) in females. The results showed that males had a higher incidence of NAFLD (χ² = 68.412, P = 0.000). The Cox regression analysis disclosed that the hazard ratios of NAFLD [95% confidence interval (CI)] were 1.431 (95% CI, 1.123~1.823), 1.610 (95% CI, 1.262-2.054), and 1.666 (95% CI, 1.287-2.157) across the second to the fourth quartile of SUA adjusted for other confounders. The SUA cutoffs, sensitivity, specificity, and area under the curve (AUC) (95% CI) were ≥288.5 μmol/L, 75.5, 46.5%, 0.637(0.616-0.658), respectively, for total; ≥319.5 μmol/L, 65.8%, 48.4%, 0.590 (0.564-0.615), respectively, for males; and ≥287.5 μmol/L, 51.0%, 75.6%, 0.662 (0.619-0.704), respectively, for females. Kaplan-Meier survival curves revealed that individuals with higher SUA level had an increased risk of NAFLD in comparison to lower SUA level (P = 0.000). Conclusion: Serum uric acid is positively correlated with NAFLD, and elevated SUA level can be used as an independent predictor for NAFLD.

Clinical characteristics of patients under 40 years old with early-onset hyperuricaemia: a retrospective monocentric study in China

OBJECTIVE

To investigate the clinical characteristics of patients with early-onset hyperuricaemia (HUC).

METHODS

A retrospective study using data from the Second Affiliated Hospital of Soochow University was conducted. 623 patients with HUC were divided into early-onset group and late-onset group. Another 201 healthy subjects ≤40 years old were regarded as control group. The data of physical measurements and biochemistry test were collected. Clinical data of early-onset group were compared with late-onset group and control group by analysis of variance (ANOVA) and χ² test. Principal component analysis (PCA) was applied. Logistic regression was used to identify the clinical factors correlated with patients with early-onset HUC.

RESULTS

The patients of early-onset group had different body mass index (BMI), serum albumin, alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AKP), gamma-glutamyltransferase (GGT), creatinine (Cr), triglyceride (TG), total cholesterol (TC), low density lipoprotein (LDL), TG/high density lipoprotein (HDL) ratio, HDL and percentage of males, hypertension (HBP) as well as fatty liver compared with healthy people in the control group. Early-onset group patients had different albumin, ALT, fasting blood glucose, Cr, percentage of males and HBP compared with late-onset group patients. PCA identified four significant patterns including PC1 (labelled 'TG and HDL'), PC2 (labelled 'fatty liver and liver enzymes'), PC3 (labelled 'TC and LDL') and PC4 (labelled 'AKP'). The results of univariate and multivariate logistic regression analysis showed that BMI, HBP and albumin were correlative factors for early onset of HUC when the patients with early-onset and late-onset HUC were involved, while gender, BMI, PC1, PC2 and PC4 were correlative factors for early-onset HUC when the early-onset and control groups were involved.

CONCLUSION

This study described a group of patients with early-onset HUC with distinct clinical features. Gender, BMI, 'TG and HDL', 'fatty liver and liver enzymes' and 'AKP' have higher values than HBP, type 2 diabetes mellitus and 'TC and LDL' in patients under 40 years old with early-onset HUC.

Urine uric acid excretion is associated with nonalcoholic fatty liver disease in patients with type 2 diabetes

AIMS

Elevated serum uric acid is closely associated with nonalcoholic fatty liver disease (NAFLD). However, the association of urine uric acid excretion (UUAE) with NAFLD has not been investigated. Our aims were to explore the associations between UUAE and NAFLD and serum alanine aminotransferase (ALT) in type 2 diabetes mellitus (T2DM).

METHODS

This cross-sectional study included 2042 Chinese inpatients with T2DM. UUAE was determined enzymatically using a single 24-h urine collection. The subjects were stratified into quartile based on UUAE levels. NAFLD was determined by ultrasonography. Elevated ALT level was defined with an ALT value >65U/L.

RESULTS

There was an obvious increase in both NAFLD prevalence (26.3%, 34.6%, 43.8%, and 56.2%, respectively, p<0.001 for trend) and ALT value [16 (12-24), 17 (13-27), 20 (14-30), and 24 (15-38) U/L, respectively, p<0.001 for trend] across the UUAE quartiles after controlling for confounders. Multiple logistic regression analyses revealed independent associations between UUAE and NAFLD (p=0.002) and elevated ALT level (p<0.001). Compared with the patients in the first quartile of UUAE, those in the second, third and fourth quartiles had 1.528-, 1.869-, and 1.906-fold risk of NAFLD, and 3.620-, 6.223-, and 10.506-fold risk of elevated ALT level in T2DM, respectively.

CONCLUSIONS

Increased UUAE levels were significantly associated with the presence of NAFLD and increase of ALT in T2DM. UUAE may be a clinically significant measure in assessing the risk of NAFLD in T2DM.

Serum Uric Acid and Mortality Form Cardiovascular Disease: EPOCH-JAPAN Study

AIM

To investigate the relationship between serum uric acid levels and cardiovascular disease in Asians.

METHODS

We examined the above relationship using the data of Evidence for Cardiovascular Prevention from Observational Cohorts in Japan (EPOCH-JAPAN Study). The data of 36,313 subjects (15,628 men and 20,685 women aged 35-89 years without histories of stroke, coronary heart disease, or cancer at baseline) were used for the analyses. Sex-specific hazard ratios (HRs) of mortality from cardiovascular disease were estimated according to the quintiles of serum uric acid using Cox hazard models stratified by cohorts.

RESULTS

During 441,771 person-years of follow-up, we documented 1,288 cardiovascular deaths. A J- or U-shaped relationship between serum uric acid level and cardiovascular disease mortality was observed. Compared with the lowest quintile of serum uric acid levels, the highest quintile was associated with an increased cardiovascular disease mortality in men [HR: 1.28; 95% confidence interval (CI): 1.01-1.63] and women (HR: 1.51; 95% CI: 1.14-1.99). However, there was no significant association with mortality from stroke, coronary heart disease or heart failure in both men and women.

CONCLUSION

This large pooled analysis in Japan suggested a J- or U-shaped relationship between serum uric acid levels and cardiovascular mortality. The highest quintile of serum uric acid levels was associated with increased cardiovascular disease mortality in both Japanese men and women.

Hyperuricemia and the risk for coronary heart disease morbidity and mortality a systematic review and dose-response meta-analysis

Considerable controversy exists regarding the association between hyperuricemia and coronary heart disease (CHD). Therefore, we performed a systematic review and dose-response meta-analysis of prospective studies to examine the controversy. Prospective cohort studies with relative risks (RRs) and 95% confidence intervals (CIs) for CHD according to serum uric acid levels in adults were eligible. A random-effects model was used to compute the pooled risk estimate. The search yielded 29 prospective cohort studies (n = 958410 participants). Hyperuricemia was associated with increased risk of CHD morbidity (adjusted RR 1.13; 95% CI 1.05 to 1.21) and mortality (adjusted RR 1.27; 95% CI 1.16 to 1.39). For each increase of 1 mg/dl in uric acid level, the pooled multivariate RR of CHD mortality was 1.13 (95% CI 1.06 to 1.20). Dose-response analysis indicated that the combined RR of CHD mortality for an increase of 1 mg uric acid level per dl was 1.02 (95% CI 0.84 to 1.24) without heterogeneity among males (P = 0.879, I² = 0%) and 2.44 (95% CI 1.69 to 3.54) without heterogeneity among females (P = 0.526, I² = 0%). The increased risk of CHD associated with hyperuricemia was consistent across most subgroups. Hyperuricemia may increase the risk of CHD events, particularly CHD mortality in females.

Hyperuricemia as risk factor for coronary heart disease incidence and mortality in the general population: a systematic review and meta-analysis

Previous meta-analyses reported no significant or weak association between hyperuricemia (HU) and coronary heart disease (CHD). We updated the literature search, systematically reviewing retrieved papers. The peer-reviewed literature published from 1965 to December 2014 was searched using Medline and Embase. We included prospective cohort studies involving adults (sample size ≥100) with no cardiovascular disease (CVD) and a follow-up of at least 1 year. Studies were excluded if they considered as outcome the CVD incidence/mortality without separately reporting data on CHD, did not adjusted for major confounders and if the 95% confidence interval (CI) for risk ratio (RR) was not available. Relative risk or hazard ratio estimates, with the corresponding CIs, were obtained. For CHD incidence 12 populations were included (457,915 subjects [53.7% males]). For CHD mortality seven populations were included (237,433 subjects [66.3% males]). The overall combined RR were 1.206 (CI 1.066–1.364, p=0.003) for CHD incidence and 1.209 (CI 1.003–1.457, p=0.047) for CHD mortality, respectively. Subgroup analysis showed a marginal (incidence) and not significant (mortality) association between HU and CHD in men, but an increased risk for CHD incidence and mortality in hyperuricemic women (RR 1.446, CI 1.323–1.581, p<0.0001, and RR 1.830, CI 1.066–3.139, p=0.028, respectively). The risk markedly increases for urate concentrations >7.0 mg/dL. HU appears to increase the risk of CHD events in the general population, mainly in adult women. This finding requires, however, further investigation.

Serum uric acid: a new therapeutic target for nonalcoholic fatty liver disease

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is a major, worldwide public health problem. NAFLD is recognized as a major cause of liver-related morbidity and mortality. However, physicians are currently limited by available treatment options. Recently, numerous studies have reported a correlation between serum uric acid (SUA) and NAFLD with numerous clinical and experimental studies demonstrating a significant correlation. This review will focus on the role of SUA in the development of NAFLD and its potential role as a new target for therapeutic intervention.

AREAS COVERED

This review discusses SUA as a significant independent factor in the development of NAFLD. Moreover, we introduce the causal relationship between SUA, metabolic syndrome, and NAFLD. We discuss two major theories of insulin resistance and inflammasomes as potential explanations of the mechanistic link between SUA and NAFLD. In addition, we review current and emerging therapeutic medications to control appropriate SUA levels.

EXPERT OPINION

There is an urgent need to develop novel, safe and effective therapies for the growing NAFLD epidemic. Reduction of SUA may be a promising potential treatment for patients with NAFLD. Clinical studies are required to determine the therapeutic effect of attenuation of hyperuricemia in humans with NAFLD.

Association between sex-specific serum uric acid and non-alcoholic fatty liver disease in Chinese adults: a large population-based study

The aim of this study was to examine the association between sex-specific serum uric acid (sUA) levels and NAFLD in a large population-based study.A total of 60,455 subjects from 2 separate medical centers were included. Sex-specific sUA quartiles (Q1-Q4) were defined: ≤330, 331-380, 381-435, and ≥436 μmol/L for male; ≤230, 231-270, 271-310, and ≥311 μmol/L for female. The odds ratios (ORs), hazard ratios (HRs), and 95% confidence intervals (CIs) for NAFLD were calculated across each quartile of sUA, using the Q1 as reference.After adjusting for known confounding variables in this study, the ORs for NAFLD in the cross-sectional population were 1.211 (95% CI 1.109-1.322), 1.519 (95% CI 1.395-1.654), 1.903 (95% CI 1.748-2.072) for Q2, Q3, and Q4, respectively. In the longitudinal population, compared with the reference group, those in Q2, Q3, and Q4 had HRs of 1.127 (95% CI 0.956-1.330), 1.380 (95% CI 1.157-1.644), 1.589 (95% CI 1.310-1.927) for NAFLD, respectively. Analysis for the sex-specific subgroup showed the adjusted ORs for Q4 versus Q1 were 2.898 (95% CI 2.36-3.588) in female and 1.887 (95% CI 1.718-2.072) in male in the cross-sectional population. In the longitudinal population, the HRs for the Q4 were 2.355 (95% CI 1.702-3.259) in female and 1.249 (95% CI 0.975-1.601) in male, compared with Q1.We report that a sex-specific sUA level is independently associated with NAFLD. The association between sUA and NAFLD was significantly greater in females than in males.

The relationship of serum uric acid with non-alcoholic fatty liver disease

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is a clinicopathological entity which is characterized by the presence of fat droplets in hepatocytes without alcohol consumption, representing a spectrum of hepatic injuries, ranging from simple steatosis (SS) to non-alcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. In recent years, experimental and observational studies suggest a role for serum uric acid (SUA) in NAFLD. However, there are few reports investigating SUA in histologically proven NAFLD. The aim of the present study was to evaluate the relationship of SUA with liver histology in non-diabetic patients with NAFLD.

DESIGN AND METHODS

A total of 242 male patients with NAFLD (102 with NASH and 140 with SS) were included. Histopathological evaluation was carried out according to Kleiner's scoring scale. Hyperuricemia was diagnosed as SUA of more than 7 mg/dL.

RESULTS

The prevalence of hyperuricemia was 33.4%. SUA levels in patients with NASH were significantly higher than those of SS (p=0.035). Univariate and multivariate analyses both demonstrated that hyperuricemia had a significant association with younger age [OR (95%CI), 0.930 (0.884-0.979), p=0.005], higher body mass index [OR (95%CI), 1.173 (1.059-1.301), p=0.002] and hepatocellular ballooning [OR (95%CI), 1.678 (1.041-2.702), p=0.033].

CONCLUSIONS

Hyperuricemia is a common finding in patients with NAFLD and is independently associated with early histological findings in this clinically relevant condition. Further longitudinal studies are needed to characterize the role of SUA in the natural history of NAFLD.

The role of uric acid in the pathogenesis of human cardiovascular disease

Hyperuricaemia is common in subjects with cardiovascular disease, but is not commonly considered a true risk factor. Recent studies suggest that uric acid is biologically active and can stimulate oxidative stress, endothelial dysfunction, inflammation and vasoconstriction. Epidemiological studies have found that uric acid can independently predict the development of hypertension, as well as stroke and heart failure. Experimentally raising uric acid in animals increases blood pressure, and pilot studies suggest that lowering uric acid in humans can reduce blood pressure in hypertensive individuals. Uric acid may also have emerging roles in the pathogenesis of kidney disease, metabolic syndrome and diabetes. More studies need to be performed on the pathophysiology and clinical consequences of hyperuricaemia in cardiovascular disease.

The association between chronic kidney disease and cardiovascular disease risk factors in atomic bomb survivors

Atomic bomb (A-bomb) radiation is associated with cardiovascular disease (CVD) and metabolic CVD risk factors. Chronic kidney disease (CKD) is also known to be a risk factor for CVD and little is known whether CKD is associated with A-bomb radiation. To examine whether CKD is associated with CVD risk factors or with A-bomb radiation in A-bomb survivors, we classified renal dysfunction in 1,040 A-bomb survivors who were examined in 2004-2007 as normal [n = 121; estimated glomerular filtration rate (eGFR) ≥ 90 ml/min/1.73 m(2)]; mild (n = 686; eGFR 60-89 ml/min/1.73 m(2)); moderate (n = 217; eGFR 30-59 ml/min/1.73 m(2)); or severe (n = 16; eGFR <30 ml/min/1.73 m(2)). Also, we diagnosed subjects in the moderate and severe renal dysfunction groups as having CKD (n = 233; eGFR <59 ml/min/1.73 m(2)). After adjusting for age, gender, and smoking and drinking habits, we looked for an association between renal dysfunction and hypertension, diabetes mellitus (DM), hyperlipidemia, and metabolic syndrome (MetS), and between renal dysfunction and A-bomb radiation. Hypertension [odds ratio (OR), 1.57; 95% confidence interval (CI), 1.12-2.20, P = 0.009]; DM (OR, 1.79; 95% CI, 1.23-2.61, P = 0.002); hyperlipidemia (OR, 1.55; 95% CI, 1.12-2.14, P = 0.008); and MetS (OR, 1.86; 95% CI, 1.32-2.63, P < 0.001) were associated with CKD (moderate/severe renal dysfunction), and hyperlipidemia and MetS were also associated with mild renal dysfunction. CKD (OR/Gy, 1.29; 95% CI, 1.01-1.63, P = 0.038) and severe renal dysfunction (OR/Gy, 3.19; 95% CI, 1.63-6.25, P < 0.001) were significantly associated with radiation dose. CKD associated with radiation may have played a role in the development of CVD among A-bomb survivors.

Serum uric acid levels predict incident nonalcoholic fatty liver disease in healthy Korean men

The objective of the study was to assess the prospective association between serum uric acid levels and incident nonalcoholic fatty liver disease in a cohort of healthy Korean men. A cohort study was performed on 5741 Korean men, 30 to 59 years of age, with no evidence of fatty liver disease on liver ultrasound and with no major risk factors for liver disease at baseline. Study participants were followed in annual or biennial health examinations between 2002 and 2008. The presence of fatty liver was determined at each examination by ultrasound. Cox proportional hazards models were used to evaluate the association of baseline and time-dependent levels of serum uric acid with incident fatty liver, adjusted for potential confounders. During 23,995 person-years of follow-up, 1717 participants developed fatty liver on ultrasound examination. After adjustment for age, body mass index, smoking, and alcohol intake, the hazard ratios (95% confidence intervals) for incident fatty liver comparing quartiles 2 to 4 of serum uric acid to quartile 1 were 1.17 (1.01-1.37), 1.28 (1.11-1.48), and 1.51 (1.31-1.73), respectively (P for trend = .001). The adjusted hazard ratio comparing participants with hyperuricemia (serum uric acid ≥7.0 mg/dL) to those with normouricemia (<7.0 mg/dL) was 1.29 (1.14-1.46). A graded and statistically significant association persisted after adjusting for other cardiometabolic factors and also in time-dependent models. Serum uric acid was an independent risk factor of incident fatty liver detected by ultrasonography. Additional research should clarify the mechanisms underlying this association and the role of hyperuricemia in the development of fatty liver.

Frequency and risk factors associated with non-alcoholic fatty liver disease in patients with type 2 diabetes mellitus

OBJECTIVE

To evaluate the frequency of non-alcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (DM2) and to describe its risk factors.

SUBJECTS AND METHODS

Blood samples of 78 patients were collected for assessment of glycemic and lipid profile, liver enzymes, TNF-alpha and HOMA-IR. The diagnosis of NAFLD was established by ultrasound.

RESULTS

NAFLD was observed in 42% of patients who had greater BMI (p < 0.001), and frequency of hypertension (p < 0.001). Metabolic syndrome was more frequent in those with NAFLD (p = 0.019). The levels of aspartate, alanine aminotransferase, gamma-glutamyl transpeptidase, uric acid, TNF-alpha, insulin and HOMA-IR were significantly higher in patients with NAFLD than those without NAFLD.

CONCLUSION

Almost half of patients with DM2 were found to have NAFLD, and they have more elevated BMI, as well as higher levels of aminotransferases, gamma-GT, uric acid, TNF-alpha, insulin and HOMA-IR than subjects without NAFLD.

Hyperuricemia and coronary heart disease: a systematic review and meta-analysis

OBJECTIVE

The role of serum uric acid as an independent risk factor for cardiovascular disease remains unclear, although hyperuricemia is associated with cardiovascular disease such as coronary heart disease (CHD), stroke, and hypertension.

METHODS

A systematic review and meta-analysis using a random-effects model was conducted to determine the risk of CHD associated with hyperuricemia in adults. Studies of hyperuricemia and CHD were identified by searching major electronic databases using the medical subject headings and keywords without language restriction (through February 2009). Only prospective cohort studies were included if they had data on CHD incidences or mortalities related to serum uric acid levels in adults.

RESULTS

Twenty-six eligible studies of 402,997 adults were identified. Hyperuricemia was associated with an increased risk of CHD incidence (unadjusted risk ratio [RR] 1.34, 95% confidence interval [95% CI] 1.19-1.49) and mortality (unadjusted RR 1.46, 95% CI 1.20-1.73). When adjusted for potential confounding, the pooled RR was 1.09 (95% CI 1.03-1.16) for CHD incidence and 1.16 (95% CI 1.01-1.30) for CHD mortality. For each increase of 1 mg/dl in uric acid level, the pooled multivariate RR for CHD mortality was 1.12 (95% CI 1.05-1.19). Subgroup analyses showed no significant association between hyperuricemia and CHD incidence/mortality in men, but an increased risk for CHD mortality in women (RR 1.67, 95% CI 1.30-2.04).

CONCLUSION

Hyperuricemia may marginally increase the risk of CHD events, independently of traditional CHD risk factors. A more pronounced increased risk for CHD mortality in women should be investigated in future research.

Hyperuricemia and coronary heart disease: a systematic review and meta-analysis

OBJECTIVE

The role of serum uric acid as an independent risk factor for cardiovascular disease remains unclear, although hyperuricemia is associated with cardiovascular disease such as coronary heart disease (CHD), stroke, and hypertension.

METHODS

A systematic review and meta-analysis using a random-effects model was conducted to determine the risk of CHD associated with hyperuricemia in adults. Studies of hyperuricemia and CHD were identified by searching major electronic databases using the medical subject headings and keywords without language restriction (through February 2009). Only prospective cohort studies were included if they had data on CHD incidences or mortalities related to serum uric acid levels in adults.

RESULTS

Twenty-six eligible studies of 402,997 adults were identified. Hyperuricemia was associated with an increased risk of CHD incidence (unadjusted risk ratio [RR] 1.34, 95% confidence interval [95% CI] 1.19-1.49) and mortality (unadjusted RR 1.46, 95% CI 1.20-1.73). When adjusted for potential confounding, the pooled RR was 1.09 (95% CI 1.03-1.16) for CHD incidence and 1.16 (95% CI 1.01-1.30) for CHD mortality. For each increase of 1 mg/dl in uric acid level, the pooled multivariate RR for CHD mortality was 1.12 (95% CI 1.05-1.19). Subgroup analyses showed no significant association between hyperuricemia and CHD incidence/mortality in men, but an increased risk for CHD mortality in women (RR 1.67, 95% CI 1.30-2.04).

CONCLUSION

Hyperuricemia may marginally increase the risk of CHD events, independently of traditional CHD risk factors. A more pronounced increased risk for CHD mortality in women should be investigated in future research.

Relationship between uric acid and hepatic steatosis among Koreans

AIM

The relationship between high uric-acid levels and hepatic steatosis, according to body mass index (BMI) categories, and their coexistence with the metabolic syndrome (MetS) were examined in the present study.

METHODS

The study involved a cross-sectional sample of 13,621 Koreans (7221 men and 6400 women) who visited a health checkup centre between 2005 and 2006. Hepatic steatosis was diagnosed using ultrasonography. Hyperuricaemia was defined as >7mg/dL for men and >6mg/dL for women. The MetS was defined as the presence of three or more MetS components-obesity (BMI >or=25.0kg/m(2)), high blood pressure, elevated levels of triglycerides and glucose, and low levels of high-density lipoprotein (HDL)-cholesterol.

RESULTS

In total, 26.2% were diagnosed with hepatic steatosis, of whom 11.9% were non-obese (BMI <25kg/m(2)) and 52.5% were obese. Hyperuricaemia was associated with hepatic steatosis in non-obese (adjusted odds ratio [AOR] of 1.4 in men and 2.2 in women) as well as in obese individuals (AOR of 1.8 in men and 2.3 in women) after adjusting for age, other MetS components and liver function tests. The AOR (95% CI) for hepatic steatosis in obese individuals with hyperuricaemia compared with non-obese individuals with normal uric-acid levels was 7.7 (6.4-9.3) in men and 12.4 (7.8-19.5) in women. The adjusted age and liver-function test ORs (95% CI) for hepatic steatosis in those with hyperuricaemia and no MetS compared with those who had normal uric acid levels and no MetS were 2.0 (1.7-2.4) in men and 3.2 (2.1-4.9) in women. The ORs (95% CI) in those with hyperuricaemia and the MetS increased to 6.9 (5.5-8.8) and 15.2 (8.4-27.4) in men and women, respectively.

CONCLUSION

Hyperuricaemia is independently associated with hepatic steatosis regardless of BMI category or the presence of the MetS in Korean adults. Further research into the causal relationship is needed.

Hyperuricemia and risk of stroke: a systematic review and meta-analysis

OBJECTIVE

To assess the association between hyperuricemia and risk of stroke incidence and mortality because hyperuricemia is hypothesized to be a risk factor for stroke and other cardiovascular disease, but, to date, results from observational studies are conflicting.

METHODS

A systematic review and meta-analysis were conducted. Studies were identified by searching major electronic databases using the Medical Subject Headings and keywords without restriction in languages. Prospective cohort studies were included only if they contained data on stroke incidences or mortalities related to serum uric acid levels in adults. Pooled risk ratios (RRs) for the association of stroke incidence and mortality with serum uric acid levels were calculated.

RESULTS

A total of 16 studies including 238,449 adults were eligible and abstracted. Hyperuricemia was associated with a significantly higher risk of both stroke incidence (6 studies; RR 1.41, 95% confidence interval [95% CI] 1.05, 1.76) and mortality (6 studies; RR 1.36, 95% CI 1.03, 1.69) in our meta-analyses of unadjusted study estimates. Subgroup analyses of studies adjusting for known risk factors such as age, hypertension, diabetes mellitus, and cholesterol still showed that hyperuricemia was significantly associated with both stroke incidence (4 studies; RR 1.47, 95% CI 1.19, 1.76) and mortality (6 studies; RR 1.26, 95% CI 1.12, 1.39). The pooled estimate of multivariate RRs did not differ significantly by sex.

CONCLUSION

Hyperuricemia may modestly increase the risks of both stroke incidence and mortality. Future research is needed to determine whether lowering uric acid level has any beneficial effects on stroke.

Association of serum uric acid level with non-alcoholic fatty liver disease: a cross-sectional study

BACKGROUND/AIM

Serum uric acid level has been suggested to be associated with factors that contribute to the metabolic syndrome. The aim of this study was to investigate the association of serum uric acid level with non-alcoholic fatty liver disease (NAFLD).

METHODS

A cross-sectional study was performed among the employees of Zhenhai Refining & Chemical Company Ltd., Ningbo, China.

RESULTS

The study included 8925 subjects (6008 men) with a mean age of 43 years. The prevalence rates of NAFLD and hyperuricemia were 11.78% and 14.71%, respectively. NAFLD patients had significantly higher serum uric acid levels than controls (370.3+/-86.6 vs. 321.1+/-82.6 micromol/L; P<0.001). The prevalence rate of NAFLD was significantly higher in subjects with hyperuricemia than in those without hyperuricemia (24.75% vs. 9.54%; P<0.001), and the prevalence rate increased with progressively higher serum uric acid levels (P value for trend <0.001). Multiple regression analysis showed that hyperuricemia was associated with an increased risk of NAFLD (odds ratio [OR]: 1.291, 95% confidence interval [CI]: 1.067-1.564; P<0.001).

CONCLUSION

Serum uric acid level is significantly associated with NAFLD, and elevated serum uric acid level is an independent risk factor for NAFLD.