Uric acid levels, kidney function, and cardiovascular mortality in US adults: National Health and Nutrition Examination Survey (NHANES) 1988-1994 and 1999-2002

Electrochemical analysis of uric acid excretion to the intestinal lumen: Effect of serum uric acid-lowering drugs and 5/6 nephrectomy on intestinal uric acid levels

Recently, extensive efforts have been made to understand the importance of the extra-renal uric acid (UA) excretion pathways and their contribution to UA-related diseases. However, the method typically used to measure UA concentrations in the intestinal lumen is difficult to real time and dynamic analysis. In this study, UA excretion in the rat intestinal lumen was measured in real time using an electrochemical method. A sensitive electrode to detect UA was constructed using a gold electrode modified with a mixed self-assembled monolayer. Excretion rate of UA in the intestine was calculated using time course data. A decrease in UA excretion rate was observed in the intestine after administration of serum UA-lowering drugs (benzbromarone, febuxostat, and topiroxostat). Inhibition of ATP-binding cassette transporter G2 (ABCG2) which has been reported as an important exporter of UA was suggested by administration of these drugs. On the other hand, an increase in excretion rate of UA was observed in the intestine of 5/6 nephrectomy rats. Upregulation of mRNA expression of the UA transporter organic anion transporter OAT3, which is related to the secretion at the basal membrane, suggested an enhancement of UA excretion by ABCG2, a high-capacity UA exporter. Observed urate excretion dynamics and mRNA expression of UA transporters in the intestine upon administration of serum UA-lowering drugs and 5/6 nephrectomy improve our understanding of the underlying mechanisms of intestinal UA excretion.

Efficacy of xanthine oxidase inhibitor for chronic kidney disease patients with hyperuricemia

BACKGROUND

Hyperuricemia is a known risk factor for end-stage renal disease. Although xanthine oxidase (XO) inhibitors are expected to protect the kidney function, evidence to this end is insufficient at present.

METHODS

This study was a multi-center, open-labeled, randomized study conducted in Mie Prefecture in Japan. Patients were included if they were between 20 and 80 years old and had a serum uric acid (sUA) level ≥ 7.0 mg/dl with or without gout, estimated glomerular filtration rate (eGFR) of 15-60 ml/min/1.73 m², and urinary protein creatinine ratio (uPCR) of 0.15-3.5 g/gCr. Patients were randomly assigned to a Topiroxostat or Febuxostat group, and the treatment target for the sUA level was < 6.0 mg/dl. The primary outcome was the change in the uPCR after 24 weeks.

RESULTS

The change in the median uPCR after 24 weeks was not statistically significant after treatment in the Topiroxostat or Febuxostat group (0.05 g/gCr and - 0.04 g/gCr, respectively). However, the sUA levels decreased significantly in both groups (Topiroxostat group: 8.6 ± 1.1 at baseline to 6.0 ± 1.1 mg/dl at 24 weeks, Febuxostat group: 8.4 ± 1.1 mg/dl at baseline to 5.9 ± 1.3 mg/dl at 24 weeks). No significant change in the eGFR after 24 weeks was noted in either the Topiroxostat or Febuxostat group (- 0.04 ± 4.59 ml/min/1.73 m² and 0.31 ± 4.70 ml/min/1.73 m², respectively).

CONCLUSIONS

In this study, XO inhibitors did not significantly reduce the uPCR in chronic kidney disease stage 3 and 4 patients with hyperuricemia.

Spectrum and dosing of urate-lowering drugs in a large cohort of chronic kidney disease patients and their effect on serum urate levels: a cross-sectional analysis from the German Chronic Kidney Disease study

Background

Despite a plethora of studies on the effect of urate-lowering therapy (ULT) in patients with chronic kidney disease (CKD), current guidelines on the treatment of hyperuricaemia and gout vary, especially concerning the need for dose adjustment of allopurinol, whose main metabolite is accumulating with declining renal function. Data on allopurinol dosing and its relationship to renal function, co-medication and sex and the resulting urate level in large cohorts are missing.

Methods

We studied a subgroup of 2378 patients of the German Chronic Kidney Disease (GCKD) study to determine prescription patterns of ULT among CKD patients under nephrological care and the relationship of ULT dose to urate levels. Prescription and dosing of ULT were manually abstracted from the patient’s paper charts at the baseline visit, in which all currently used medications and their dosing were recorded.

Results

In this cohort, 39.6% were women, the mean estimated glomerular filtration rate (eGFR) was 51.3 ± 19.3 mL/min/1.73 m² and the mean age was 59.0 ± 12.4 years. Of the 2378 examined patients, 666 (28.0%) received ULT. The dose of ULT was available for 572 patients. The main ULT agent was allopurinol (94.4%), followed by febuxostat (2.9%) and benzbromarone (2.6%). Of the 540 patients who used allopurinol with a reported daily dose, 480 had an eGFR <60 mL/min/1.73 m² and 320 had an eGFR <45 mL/min/1.73 m², 31.5% of the latter (n = 101) received a dose >150 mg/day, the recommended maximal dose for this level of eGFR. The prescribed dose was not related to eGFR: the median eGFR for patients taking 100, 150 and 300 mg/day was 40 [interquartile range (IQR) 32–49], 43 (34–52) and 42 (35–54) mL/min/1.73 m², respectively. Patients with lower doses of allopurinol had higher serum urate levels than patients with higher (than recommended) allopurinol doses. Sex, alcohol intake, eGFR, use of diuretics and treatment with allopurinol were independent determinants of serum urate levels in multivariate regression analysis.

Conclusions

The most frequently used drug to lower serum urate levels in this CKD cohort was allopurinol. Even in patients regularly seen by nephrologists, the dose of allopurinol is often not adjusted to the current eGFR. Patients with higher ULT doses achieved better control of their serum urate levels. Lowering of serum urate in CKD patients requires balancing potential adverse effects of allopurinol with suboptimal control of serum urate levels.

Effects of hyperuricemia on incident renal replacement therapy and all-cause mortality among patients with chronic kidney disease stages 3-5: a retrospective cohort study

BACKGROUND

Findings regarding the effects of hyperuricemia on renal function and mortality have been inconsistent.

OBJECTIVES

To investigate the effects of hyperuricemia on incident renal replacement therapy and all-cause mortality among patients with chronic kidney disease (CKD).

DESIGN AND SETTING

Retrospective cohort study conducted in a medical center in Taiwan.

METHODS

Patients with CKD in stages 3-5, without histories of renal replacement therapy, were consecutively recruited from 2007 to 2013. Their medical history, laboratory and medication data were collected from hospital records. The mean uric acid level in the first year of follow-up was used for analyses. Hyperuricemia was defined as mean uric acid level ≥ 7.0 mg/dl in men or ≥ 6.0 mg/dl in women. The primary outcomes were incident renal replacement therapy and all-cause mortality, and these data were retrospectively collected from hospital records until the end of 2015.

RESULTS

A total of 4,381 patients were analyzed (mean age 71.0 ± 14.8 years; males 62.7%), and the median follow-up period was 2.5 years. Patients with hyperuricemia were at increased risk of incident renal replacement therapy and all-cause mortality, especially those with CKD in stages 4 or 5. Compared with patients with CKD in stage 3 and normouricemia, patients with CKD in stages 4 or 5 presented significantly higher risk of all-cause mortality only if they had hyperuricemia.

CONCLUSIONS

In patients with CKD in stages 3-5, hyperuricemia was associated with higher risk of incident renal replacement therapy and all-cause mortality. Whether treatment with uric acid-lowering drugs in these patients would improve their outcomes merits further investigation.

Elevated Serum Uric Acid and Self-Reported Heart Failure in US Adults: 2007-2016 National Health and Nutrition Examination Survey

INTRODUCTION

There is limited evidence examining the relationship between elevated serum uric acid (sUA) concentration and heart failure (HF) in United States (US) adults. The aim of the present study was to examine the association(s) between elevated sUA and HF using a nationally representative sample of US adults.

METHODS

The final sample with complete data for this analysis (n = 17,349) included men and women aged ≥40 years who participated in the 2007-2016 National Health and Nutrition Examination Survey. Self-reported diagnosis of HF was assessed via interview. Elevated sUA was defined as values >6.0 mg/dL for women and >7.2 mg/dL for men. Multivariable gender-stratified logistic regression was utilized to examine the odds of self-reported HF.

RESULTS

The estimated prevalence of HF was 3.9 and 3.4% among men and women, respectively. Age-adjusted analysis revealed significantly increased odds of HF in men (OR 2.79; 95% CI 2.15-3.84, p < 0.01) and women (OR 3.24; 95% CI 2.37-4.44, p < 0.01) with elevated sUA. This relationship remained statistically significant following adjustment for age, race, education, income, alcohol consumption, smoking status, blood pressure, diabetes, physical activity level, cholesterol, creatinine level, and body mass index in men (OR 1.70; 95% CI 1.13-2.57 p < 0.05) and women (OR 1.74; 95% CI 1.18-2.58, p < 0.05).

CONCLUSIONS

In a representative sample of US adults, having an elevated sUA concentration was associated with significantly increased odds of HF when compared to adults with normal sUA.

Human concentrations of uric acid scavenges adaptive and maladaptive reactive oxygen species in isolated rat hearts subjected to ischemic stress

Uric acid is a purine degradation product but also an important antioxidant and reactive oxygen species (ROS) scavenger. Experimental settings that mimic myocardial ischemia-reperfusion have not included uric acid despite that it is always present in human extracellular fluid and plasma. We hypothesized that uric acid has an important role in myocardial ROS scavenging. Here, we tested the cardiac response to uric acid on infarct size following ischemia-reperfusion with and without exacerbated oxidative stress due to acute pressure overload and during preconditioning. We also examined mitochondrial respiration and ROS-induced mitochondrial permeability transition pore opening. Under exacerbated ROS stress induced by high-pressure perfusion, uric acid lowered oxidative stress and reduced infarct size. In contrast, uric acid blocked cardioprotection induced by ischemic preconditioning. However, this effect was reversed by probenecid, an inhibitor of cellular uptake of uric acid. In accordance, in intact cardiomyocytes, extracellular uric acid reduced the susceptibility of mitochondria towards opening of the permeability transition pore, suggesting that uric acid may prevent ischemia-reperfusion injury due to scavenging of maladaptive ROS. Moreover, as uric acid also scavenges adaptive ROS, this may interfere with preconditioning. Altogether, uric acid might be a confounder when translating preclinical experimental results into clinical treatment.

Sex differences by design and outcome in the Safety of Urate Elevation in PD (SURE-PD) trial

OBJECTIVE

To investigate whether women and men with Parkinson disease (PD) differ in their biochemical and clinical responses to long-term treatment with inosine.

METHODS

The Safety of Urate Elevation in Parkinson's Disease (SURE-PD) trial enrolled 75 people with early PD and baseline serum urate below 6 mg/dL and randomized them to 3 double-blinded treatment arms: oral placebo or inosine titrated to produce mild (6.1-7.0 mg/dL) or moderate (7.1-8.0 mg/dL) serum urate elevation for up to 2 years. Parkinsonism, serum urate, and plasma antioxidant capacity were measured at baseline and repeatedly on treatment; CSF urate was assessed once, at 3 months. Here in secondary analyses results are stratified by sex.

RESULTS

Inosine produced an absolute increase in average serum urate from baseline that was 50% greater in women (3.0 mg/dL) than in men (2.0 mg/dL), consistent with expected lower baseline levels in women. Similarly, only among women was CSF urate significantly greater on mild or moderate inosine (+87% [p < 0.001] and +98% [p < 0.001], respectively) than on placebo (in contrast to men: +10% [p = 0.6] and +14% [p = 0.4], respectively). Women in the higher inosine dosing group showed a 7.0 Unified Parkinson's Disease Rating Scale (UPDRS) points/year lower rate of decline vs placebo (p = 0.01). In women, slower rates of UPDRS change were associated with greater increases in serum urate (r = -0.52; p = 0.001), and with greater increases in plasma antioxidant capacity (r = -0.44; p = 0.006). No significant associations were observed in men.

CONCLUSIONS

Inosine produced greater increases in serum and CSF urate in women compared to men in the SURE-PD trial, consistent with the study's design and with preliminary evidence for slower clinical decline in early PD among women treated with urate-elevating doses of inosine.

CLINICALTRIALSGOV IDENTIFIER

NCT00833690.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that inosine produced greater urate elevation in women than men and may slow PD progression in women.

Relationship of reduced glomerular filtration rate with alterations in plasma free amino acids and uric acid evaluated in healthy control and hypertensive subjects

The potential association between altered levels of plasma free amino acids (PFAAs) and uric acid (UA) with estimated glomerular filtration rate (eGFR) remains unknown among patients with hypertension. A total of 2804 healthy controls and 2455 hypertensive patients were included in the current analysis. eGFR was defined as reduced when it was <60 ml/min/1.73 m². The associations between reduced eGFR and individual PFAAs and UA in the healthy control and hypertension groups were explored by logistic regression analyses adjusted for potential confounding variables. Results show that UA had a significant positive association with reduced eGFR in both healthy control and hypertension groups (P < 0.001). Among the PFAAs, citrulline, glycine and phenylalanine showed significant positive associations with reduced eGFR in both healthy control (P < 0.01 to 0.001) and hypertension (P < 0.001) groups. Moreover, alanine, asparagine and methionine achieved significant positive associations with reduced eGFR only in the hypertension group (P < 0.01 to 0.001). Conversely, serine showed significant inverse associations with reduced eGFR in the hypertension group only (P < 0.001). Our findings provide first evidence for a strong relationship between distinct patterns of PFAAs and elevated UA with reduced eGFR in hypertension. The findings may appear useful in developing effective strategies for the prevention or early detection and treatment of declined kidney function in hypertension.

Comparing Cardiovascular Safety of Febuxostat and Allopurinol in the Real World: A Population-Based Cohort Study

OBJECTIVE

To determine and compare the risk of cardiovascular events and mortality of febuxostat and allopurinol use.

PATIENTS AND METHODS

We conducted a cohort study using the Taiwan National Health Insurance Research Database. New users of febuxostat and allopurinol between April 1, 2012 and December 31, 2015 were identified, and the two groups were 1:1 matched by propensity score, benzbromarone use history, renal impairment, and time of drug initiation. The risk of major adverse cardiovascular events (MACEs), venous thromboembolism (VTE), heart failure (HF) hospitalization, atrial fibrillation hospitalization, cardiovascular (CV) death, and all-cause mortality was assessed using Cox proportional hazards models. The dose-response relationship between xanthine oxidase inhibitor use and adverse CV outcomes were also determined.

RESULTS

A total of 44,111 patients were included for each group, and all baseline covariates were well matched. Febuxostat users were at a significantly higher risk for HF hospitalization (hazard ratio [HR], 1.22; 95% CI, 1.13-1.33), atrial fibrillation hospitalization (HR, 1.19; 95% CI, 1.05-1.36), and CV death (HR, 1.19; 95% CI, 1.03-1.36) than allopurinol users, whereas no difference was found for the major adverse cardiac events composite endpoint, venous thromboembolism, myocardial infarction, ischemic stroke, and all-cause mortality. The elevated risk of HF hospitalization was consistent throughout the primary and sensitivity analyses. In addition, febuxostat increased the risk of adverse CV outcomes in a dose-dependent manner.

CONCLUSION

The use of febuxostat, compared with allopurinol, was associated with a significantly increased risk of adverse CV events. Higher febuxostat doses had a greater impact. Further studies are needed to investigate the mechanisms linking febuxostat to adverse CV outcomes.

Uric Acid Is an Independent Risk Factor for Decline in Kidney Function, Cardiovascular Events, and Mortality in Patients With Type 1 Diabetes

OBJECTIVE

Previous studies have provided inconclusive results on the role of uric acid (UA) in risk prediction. Here we aimed to improve the power and precision of the predictive value of UA for the risk of decline in kidney function, cardiovascular events (CVEs), and mortality in patients with type 1 diabetes (T1D).

RESEARCH DESIGN AND METHODS

Plasma UA was measured in 670 patients with T1D and various degrees of albuminuria, ranging from normoalbuminuria to macroalbuminuria. Associations of UA with an estimated glomerular filtration rate (eGFR) decline of ≥30%, CVEs, and mortality were analyzed. The median follow-up time was 5.3 years [interquartile range (IQR) 2.7-6.2 years] for a decline in eGFR of ≥30%, 5.8 years (2.5-6.4 years) for progression in albuminuria status, 5.1 years (4.7-5.6 years) for CVE, and 6.2 years (5.8-6.7 years) for mortality. Both univariable and multivariable associations of UA with relevant outcomes and variables were reported. Hazard ratios (HRs) were calculated per doubling of the UA level.

RESULTS

A doubling in UA level was associated with a higher risk of decline in eGFR of ≥30% (n = 89) (HR 3.18 [IQR 1.71-5.93]; P < 0.001), CVE (n = 94) (HR 2.25 [IQR 1.20-4.21]; P = 0.011), and mortality (n = 58) (HR 2.58 [IQR 1.12-5.90]; P = 0.025) in adjusted analyses. Adding UA to the adjusted model including conventional risk factors improved the relative integrated discrimination index by 12.6% for a decline in eGFR of ≥30% (P < 0.001), 6.5% for CVE (P = 0.010), and 11.8% (P = 0.003) for mortality. A doubling in UA level was also associated with a steeper decline in eGFR (P < 0.0026) and a steeper increase in urine albumin-to-creatinine ratio (P < 0.0027) in adjusted analysis.

CONCLUSIONS

In individuals with T1D, a higher UA level is associated with a higher risk of decline in kidney function, CVE, and mortality, independently of other risk factors. Our results suggest that UA has a promising role in risk stratification among individuals with T1D.

Reference interval and upper decission limit for serum uric acid – an evidence-based approach on Romanian population using an a posteriori method

Introduction. There is accumulating evidence that high normal serum uric acid (SUA) levels of 6-7 mg/dL are associated with cardiovascular morbidity and metabolic syndrome (MetS), hence the need to redefine its upper limit of normal (ULN). We aimed to derive ULN based on statistics and evidence in a representative sample of the population and to observe its relation to MetS components.

Methods. All SUA measurements form a university rheumatology hospital were extracted between January 5th 2010 and March 21st 2018. SUA levels were measured by a single biochemist a unique type of commercially available kit. Follow-up measurements, patients with diagnoses influencing SUA levels and outlying measurements were excluded. ULNs were studied using least square analysis.

Results. Of the 22503 SUA measurements in the database, only 3318 came from normal individuals: 33.3% men (n=1105), 66.7% women (n = 2213). Least square analysis revealed the following SUA reference intervals (RI): 3.43-6.19 mg/dL for the combined sample; 4.44-7.01 mg/dL for men, 3.28-5.56 mg/dL for women. The values corresponding to the 66th percentile of each group presented lower ULNs: 5.36 mg/dL for all, 6.10 mg/dL for men, 4.90 mg/dL for women. The prevalence of hyperuricemia increased from 13.8% (manufacturer’s gender-specific ULN) to 19.9% (derived ULN). Mean SUA levels significantly increased with the number of MetS components.

Conclusion. We recommend that hyperuricemia should be defined using a statistical approach of ULN selection corresponding to the genderand population-specific 66th percentile of data range.

Uric acid and progression of chronic kidney disease

The association between serum uric acid levels and human disease has garnered intense interest over the last decade including chronic kidney disease. Animal studies have provided evidence for a potential mechanistic role of uric acid in promoting progression of chronic kidney disease. Epidemiologic studies have also suggested an association between elevated serum uric acid levels and worsening renal function in the general population as well as in patients with chronic kidney disease. However, there is currently insufficient evidence to recommend the use of uric acid-lowering therapy to delay progression of chronic kidney disease in this patient population. Adequately powered, randomized, placebo-controlled trials are required to more precisely evaluate the risk and benefits of uric acid-lowering therapy in pediatric patients.

Potential Dangers of Serum Urate-Lowering Therapy

In observational studies, high serum urate levels are associated with adverse outcomes, including mortality. However, the hypothesis that urate-lowering may improve nongout outcomes has not been confirmed by placebo-controlled clinical trials. On the contrary, 7 recent placebo-controlled trials of urate-lowering drugs with different mechanisms of action (uricosuric: lesinurad; xanthine oxidase inhibition: febuxostat; uricase: pegloticase) have observed higher mortality or trends to higher mortality in gout patients, with the largest decreases in serum urate. Because all urate-lowering mechanisms were implicated, this raises safety concerns about urate-lowering itself. Far from unexpected, the higher mortality associated with more intense urate-lowering is in line with the U-shaped association of urate with mortality in some observational studies. Urate accounts for most of the antioxidant capacity of plasma, and strategies to increase urate are undergoing clinical trials in neurological disease. Post hoc analysis of recent trials should explore whether the magnitude of urate-lowering is associated with adverse outcomes, and safety trials are needed before guidelines recommend lowering serum urate below certain thresholds.

Urate-lowering therapy alleviates atherosclerosis inflammatory response factors and neointimal lesions in a mouse model of induced carotid atherosclerosis

Hyperuricemia (HU) is a cause of gout. Clinical studies show a link between HU and cardiovascular disease. However, the role of soluble serum urate (SU) on atherosclerosis development remains elusive. We aimed to use a new HU mouse model [Uricase/Uox knockout (KO)] to further investigate the relationship between HU and atherosclerosis. A mouse model by perivascular collar placement of induced carotid atherosclerosis was established in male Uox-KO mice. The Uox-KO mice had elevated SU levels and enhanced levels of atherosclerosis inflammatory response proteins. In contrast, Uox-KO mice with carotid atherosclerosis showed severe neointimal changes in histology staining consistent with increases in intimal area and increases in proliferating cell nuclear antigen (PCNA)- and F4/80-positive cells. Allopurinol reduced neointimal areas induced by the perivascular collar in hyperuricemic mice, accompanied by decreased expression of PCNA- and F4/80-positive cells. Urate-lowering treatment alleviated atherosclerosis inflammatory response factors and reactive oxygen species (ROS) intensities in both collar placement Uox-KO mice and urate-stimulated human umbilical vein endothelial cells (HUVECs). In vitro results using HUVECs showed ROS was induced by urate and ROS induction was abrogated using antioxidants. These data demonstrate that urate per se does not trigger atherosclerosis intima lesions in male mice. Urate worsens carotid neointimal lesions induced by the perivascular collar and urate-lowering therapy partially abrogates the effects. The current study warrants clinical studies on the possible benefits of urate-lowering therapy in atherosclerosis patients with HU.

Gout lessons from 2018: CARES, a direct comparison of febuxostat vs allopurinol, and CANTOS, IL1 blocker for cardiovascular risk minimisation

In the Cardiovascular Safety of Febuxostat and Allopurinol in Patients with Gout and Cardiovascular Morbidities (CARES) trial conducted by White et al. (March 29 issue from NEJM), all-cause mortality and cardiovascular mortality are found to be higher among patients randomly assigned to febuxostat compared to allopurinol, but significant flaws are a clear lack of treat to target strategy with more powered treatment in the febuxostat arm, dysbalance with cardiovascular risk factors selectively in again the febuxostat arm, and discontinuation of the trial regimen in over 50% of patients with discontinuation of follow-up in about 45%. With these flaws, conclusions such as febuxostat-associated higher mortality are potentially if not probably incorrect, and thus febuxostat to be used not as first-line therapy may well be an invalid consequence? The paper here describes potential lessons to be taken.

US National Health and Nutrition Examination Survey Arthritis Initiatives, Methodologies and Data

The US National Health and Nutrition Examination Survey (NHANES) has collected population-based, nationally representative examination, laboratory, and radiographic data for arthritis and musculoskeletal diseases for more than 50 years. The resulting body of data and publications are substantial, yet much data remain unpublished. This review provides a basic understanding of the design and capabilities of the NHANES survey, reviewing the major accomplishments in the area of arthritis and musculoskeletal diseases. Currently available US National Health and Nutrition Examination Survey arthritis-related datasets are identified. Guidelines for using these data, and opportunities for data analysis and designing future studies are presented.

Modern approaches to management of cardiovascular risk factors at patients with diabetes mellitus type 2

Diabetes mellitus (DM) type 2 is the serious progressing chronic disease representing independent risk factor of development of cardiovascular complications. The mortality from cardiovascular diseases at the persons suffering from DM type 2 continues to grow around the world, despite constant augmentation of expenses on treatment and prophylaxis. In this article factors of cardiovascular risk at DM are analyzed and possible ways of their correction are surveyed.

Low urine pH affects the development of metabolic syndrome, associative with the increase of dyslipidemia and dysglycemia: Nationwide cross-sectional study (KNHANES 2013-2015) and a single-center retrospective cohort study

INTRODUCTION

Low urine pH (UpH) and high serum uric acid are considered evidence of metabolic disorders. The effect of low UpH on the development of metabolic syndrome (MetS) is less clear than that of high serum uric acid. We investigated the association between low UpH on the development of MetS and its components: central obesity, dyslipidemia, hypertension, and dysglycemia.

METHODS

Two studies were conducted based on 2 datasets. The cross-sectional study included 14,511 subjects aged 19-80 years, based on the Korea National Health and Nutrition Examination Survey in 2013-2015. The retrospective cohort study included 3,453 subjects aged 19-80 years without MetS at the first checkup, who underwent at least 3 health checkups at a single tertiary hospital between 2011 and 2017. UpH was measured using an automatic urine analyzer in the range of 5.0-9.0 at first visit.

RESULTS

In the cross-sectional study, low UpH (= 5.0) was associated with the prevalence of MetS (odds ratio [OR] = 1.480, 95% confidence interval [CI] 1.334-1.643, p<0.001), particularly central obesity, dyslipidemia, and dysglycemia (OR ranges 1.282-1.422, p<0.001, all). In the retrospective cohort study, compared with the highest UpH subgroup, the lowest UpH subgroup (= 5.0) was associated with higher risk of MetS development (hazard ratio = 1.394, 95% CI 1.096-1.772, p = 0.007). The incident risk of MetS increased from the highest to lowest UpH subgroups (p for trend = 0.020), among which dyslipidemia and dysglycemia increased (p for trend <0.01, all).

CONCLUSION

Low UpH can be used as a surrogate marker of MetS and affects the development of MetS, associative with the increase of dyslipidemia and dysglycemia in those without MetS. If UpH is ≤5.0, efforts to prevent metabolic disorders are warranted.

The effect of electrolyte balance on the voice in hemodialysis patients

OBJECTIVE

The aim of the study was to demonstrate the effect of blood electrolytes on the voice in chronic hemodialysis patients.

METHODS

The study included a total of 59 hemodialysis patients. Pre- and post-dialysis voice recordings were performed. In the analysis of vocal acoustic parameters, fundamental frequency (F0), jitter, shimmer, the noise-to-harmonics ratio (NHR), and F0 minimum and F0 maximum were measured. The Voice Handicap Index-10 (VHI-10), and maximum phonation time (MPT) were evaluated. For perceptual evaluation, the GRBAS scale was used. The duration of dialysis (years) and changes in weight during dialysis were recorded for each patient. From venous blood samples, measurements were taken of hemoglobin (Hb), albumin, Na+, K+, creatinine, uric acid, phosphorus, Ca++, and parathormone.

RESULTS

The difference in the pre and post-dialysis values of F0, shimmer, NHR and MPT were found to be statistically significant (p = 0.001). The only variable determined to have an effect on the change in F0 values was uric acid, and the change in the F0 values was statistically significant (p = 0.009). The only variable determined to have an effect on the change in shimmer values was sodium, and the change was statistically significant (p = 0.034). The only variable determined to have an effect on the change in NHR values was creatinine, and the change in the NHR values was statistically significant (p = 0.028). Hb and the duration of dialysis were determined to have a statistically significant effect on the change in MPT values (p = 0.001).

CONCLUSIONS

The results showed that uric acid was the agent creating a reduction in vocal cord vibration, the agent increasing the difference between vibration waves was Na+, and creatinine increased the NHR rate. The effect of these variables can be considered important in the understanding of vocal cord physiology.

Is increased uric acid a risk factor or a defensive response? The Campania Salute Network

BACKGROUND AND AIMS

Circulating uric acid (UA) is positively associated with body mass index (BMI), blood glucose, blood pressure (BP), markers of inflammation, and altered lipid profile. UA has also anti-oxidative properties which might be beneficial for cardiovascular (CV) system. It is still debated whether or not UA is independently associated with increased CV morbidity and/or mortality.

METHODS AND RESULTS

We studied prognostic impact of UA in 8833 hypertensive adults (mean age 53 ± 12 yrs, 3857 women) from the Campania Salute Network, without prevalent CV disease and more than stage 3 CKD. We calculated standardized UA Z-score, adjusted for age, sex, glomerular filtration rate, and BMI. Low and high UA and UA Z-score quartiles were compared to the 2 middle quartiles assumed to be "normal". Prevalence of obesity and diabetes was higher in low and high than in normal UA Z-score group (all p < 0.001). Systolic BP, left ventricular mass, carotid intima thickness were significantly higher and ejection fraction was reduced in the presence of high UA Z-score (all p < 0.001). Over 33-months average follow-up, incident major CV end-points (MACE) were not significantly different among low, normal and high UA or UA Z-score. In the latter analysis, however, incident MACE tended to be more frequent in the low than the high UA Z-score. Despite the results of multivariable analyses, the effect of less aggressive therapy in low UA Z-score cannot be excluded with certainty.

CONCLUSION

In treated hypertensive patients, high levels of UA normalized for major biological determinants do not independently predict CV outcome. CLINICALTRIALS.

GOV IDENTIFIER

NCT02211365.

Impact of uric acid levels on the risk of long-term cardiovascular mortality in patients with type 2 diabetes mellitus

BACKGROUND

Hyperuricemia is associated to cardiovascular disease. However, the contribution of uric acid (UA) to cardiovascular mortality in diabetic patients is controversial.

OBJECTIVE

To assess the impact of UA levels on the risk of cardiovascular mortality risk in a cohort of patients with type 2 diabetes mellitus (T2DM).

PATIENTS AND METHODS

A prospective cohort study on outpatients with T2DM. The clinical endpoint was cardiovascular death. Anthropometric, demographic, clinical, and biochemical variables were collected, including UA levels, urinary albumin excretion and estimated glomerular filtration rate. The independent contribution of UA levels to cardiovascular mortality was assessed using multivariate Cox regression models, progressively adjusted for potential confounders.

RESULTS

A total of 452 patients with a mean age of 65.9 (SD 9.5) years were enrolled. Mean UA level was 4.2mg/dL. Quartiles of UA levels were Q1 < 3.3; Q2: 3.3-4.2; Q3: 4.3-5.1; Q4 > 5.1mg/dL. UA levels significantly correlated with estimated glomerular filtration rate (Rho=-0.227; p<0.001). During a median follow-up time of 13 years, cardiovascular mortality rates were higher in Q4 of the UA distribution (Q1: 10.7; Q2: 11.7; Q3: 10.7; Q4: 21.6 per 1000 patient-years; p = 0.027). UA was a predictor of cardiovascular mortality in the univariate analysis (HR1mg/dL = 1.30; p=0.002), but not in a multivariate analysis adjusted for urinary albumin excretion and eGFR (HR1mg/dL=1.20; p=0.12).

DISCUSSION AND CONCLUSIONS

High UA levels are associated to cardiovascular mortality in patients with T2DM. However, the role of UA may be mediated by impaired kidney function in patients with hyperuricemia.

Serum uric acid level as a cardio-cerebrovascular event risk factor in middle-aged and non-obese Chinese men

AIM

The role of uric acid as a risk factor for cardio-cerebrovascular diseases is controversial. In this study, we aimed to investigate the relationship between serum uric acid level and the risk of cardio-cerebrovascular events in middle-aged and non-obese Chinese men.

METHODS

We included 3152 participants from the health examination center of Tongji Hospital from June 2007 to June 2010. Clinical examination and medical records were collected at the annual health examination. The hazard ratios (HRs) of uric acid for cardio-cerebrovascular events were calculated by Cox proportional hazards models. Generalized additive model and threshold effect analysis were used to explore the non-linear relationship between serum uric acid level and the incidence of cardio-cerebrovascular event.

RESULT

The mean follow-up time was 52 months. When the participants were classified into four groups by the serum acid quarter (Q1-Q4), the HRs (95% CI) of Q2-Q4 for cardio-cerebrovascular events were 1.26 (0.83, 1.92), 1.97 (1.33, 2.91) and 2.05 (1.40, 3.01), respectively, compared with the reference (Q1). The actual incidence and conditional incidence of cardio-cerebrovascular events in the high serum acid group were higher than those in the low serum acid group, which were stratified by the turning point (sUA = 372 μmol/L). We also showed a strong prognostic accuracy of the multiple variable-based score in 3 years and 5 years, with area under the receiver operating characteristic (ROC) curve of 0.790 (0.756-0.823) and 0.777 (0.749-0.804), respectively.

CONCLUSION

Serum uric acid level is a strong risk factor for cardio-cerebrovascular events.

Hyperuricemia, Acute and Chronic Kidney Disease, Hypertension, and Cardiovascular Disease: Report of a Scientific Workshop Organized by the National Kidney Foundation

Urate is a cause of gout, kidney stones, and acute kidney injury from tumor lysis syndrome, but its relationship to kidney disease, cardiovascular disease, and diabetes remains controversial. A scientific workshop organized by the National Kidney Foundation was held in September 2016 to review current evidence. Cell culture studies and animal models suggest that elevated serum urate concentrations can contribute to kidney disease, hypertension, and metabolic syndrome. Epidemiologic evidence also supports elevated serum urate concentrations as a risk factor for the development of kidney disease, hypertension, and diabetes, but differences in methodologies and inpacts on serum urate concentrations by even subtle changes in kidney function render conclusions uncertain. Mendelian randomization studies generally do not support a causal role of serum urate in kidney disease, hypertension, or diabetes, although interpretation is complicated by nonhomogeneous populations, a failure to consider environmental interactions, and a lack of understanding of how the genetic polymorphisms affect biological mechanisms related to urate. Although several small clinical trials suggest benefits of urate-lowering therapies on kidney function, blood pressure, and insulin resistance, others have been negative, with many trials having design limitations and insufficient power. Thus, whether uric acid has a causal role in kidney and cardiovascular diseases requires further study.

How Does Empagliflozin Reduce Cardiovascular Mortality? Insights From a Mediation Analysis of the EMPA-REG OUTCOME Trial

OBJECTIVE

In the BI 10773 (Empagliflozin) Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients (EMPA-REG OUTCOME) trial involving 7,020 patients with type 2 diabetes and established cardiovascular (CV) disease, empagliflozin given in addition to standard of care reduced the risk of CV death by 38% versus placebo (hazard ratio [HR] 0.62 [95% CI 0.49, 0.77]). This exploratory mediation analysis assesses the extent to which treatment group differences in covariates during the trial contributed to CV death risk reduction with empagliflozin.

RESEARCH DESIGN AND METHODS

Effects of potential mediators, identified post hoc, on the HR for CV death with empagliflozin versus placebo were analyzed by Cox regression models, with treatment group adjusted for the baseline value of the variable and its change from baseline or updated mean (i.e., considering all prior values), each as a time-dependent covariate. HRs were compared with a model without adjustment for covariates. Multivariable analyses also were performed.

RESULTS

Changes in hematocrit and hemoglobin mediated 51.8% and 48.9%, respectively, of the effect of empagliflozin versus placebo on the risk of CV death on the basis of changes from baseline, with similar results in analyses on the basis of updated means. Smaller mediation effects (maximum 29.3%) were observed for uric acid, fasting plasma glucose, and HbA_1c. In multivariable models, which incorporated effects of empagliflozin on hematocrit, fasting glucose, uric acid, and urine albumin:creatinine ratio, the combined changes from baseline provided 85.2% mediation, whereas updated mean analyses provided 94.6% mediation of the effect of empagliflozin on CV death.

CONCLUSIONS

In this exploratory analysis from the EMPA-REG OUTCOME trial, changes in markers of plasma volume were the most important mediators of the reduction in risk of CV death with empagliflozin versus placebo.

Biochemical and Clinical Impact of Organic Uremic Retention Solutes: A Comprehensive Update

In this narrative review, the biological/biochemical impact (toxicity) of a large array of known individual uremic retention solutes and groups of solutes is summarized. We classified these compounds along their physico-chemical characteristics as small water-soluble compounds or groups, protein bound compounds and middle molecules. All but one solute (glomerulopressin) affected at least one mechanism with the potential to contribute to the uremic syndrome. In general, several mechanisms were influenced for each individual solute or group of solutes, with some impacting up to 7 different biological systems of the 11 considered. The inflammatory, cardio-vascular and fibrogenic systems were those most frequently affected and they are one by one major actors in the high morbidity and mortality of CKD but also the mechanisms that have most frequently been studied. A scoring system was built with the intention to classify the reviewed compounds according to the experimental evidence of their toxicity (number of systems affected) and overall experimental and clinical evidence. Among the highest globally scoring solutes were 3 small water-soluble compounds [asymmetric dimethylarginine (ADMA); trimethylamine-N-oxide (TMAO); uric acid], 6 protein bound compounds or groups of protein bound compounds [advanced glycation end products (AGEs); p-cresyl sulfate; indoxyl sulfate; indole acetic acid; the kynurenines; phenyl acetic acid;] and 3 middle molecules [β₂-microglobulin; ghrelin; parathyroid hormone). In general, more experimental data were provided for the protein bound molecules but for almost half of them clinical evidence was missing in spite of robust experimental data. The picture emanating is one of a complex disorder, where multiple factors contribute to a multisystem complication profile, so that it seems of not much use to pursue a decrease of concentration of a single compound.

Investigation of the transport of xanthine dehydrogenase inhibitors by the urate transporter ABCG2

Hyperuricemia induces gout and kidney stones and accelerates the progression of renal and cardiovascular diseases. Adenosine 5'-triphosphate-binding cassette subfamily G member 2 (ABCG2) is a urate transporter, and common dysfunctional variants of ABCG2, non-functional Q126X (rs72552713) and semi-functional Q141K (rs2231142), are risk factors for hyperuricemia and gout. A recent genome wide association study suggested that allopurinol, a serum uric acid-lowering drug that inhibits xanthine dehydrogenase, is a potent substrate of ABCG2. In this study, we aimed to examine the transport of xanthine dehydrogenase inhibitors via ABCG2. Our results show that ABCG2 transports oxypurinol, an active metabolite of allopurinol, whereas allopurinol and febuxostat, a new xanthine dehydrogenase inhibitor, are not substrates of ABCG2. The amount of oxypurinol transported by ABCG2 vesicles significantly increased in the presence of ATP, compared to that observed with mock vesicles. Since the half-life of oxypurinol is longer than that of allopurinol, the xanthine dehydrogenase-inhibiting effect of allopurinol mainly depends on its metabolite, oxypurinol. Our results indicate that the serum level of oxypurinol would increase in patients with ABCG2 dysfunction.

Uric Acid Level Has a J-Shaped Association with Arterial Stiffness in Korean Postmenopausal Women

Background

Uric acid has been reported to function both as an oxidant or antioxidant depending on the context. A previous study in the Korean population reported a positive linear association between serum uric acid level and arterial stiffness in men, but little is known about how serum uric acid level is related to the risk of increased arterial stiffness in Korean postmenopausal women.

Methods

We performed a cross-sectional study of 293 subjects who participated in a health examination program run by the health promotion center of Gangnam Severance Hospital between October 2007 and July 2010. High brachial-ankle pulse wave velocity was defined as a brachial-ankle pulse wave velocity of more than 1,450 cm/s. The odds ratios (ORs) for high brachial-ankle pulse wave velocity were calculated using multivariate logistic regression analysis across uric acid quartiles after adjusting for other indicators of cardiovascular risk.

Results

The 293 postmenopausal women were divided into quartiles according to uric acid level. The mean brachial-ankle pulse wave velocity values of each quartile were as follows: Q1, 1,474 cm/s; Q2, 1,375 cm/s; Q3, 1,422 cm/s; Q4, 1,528 cm/s. The second quartile was designated as the control group based on mean brachial-ankle pulse wave velocity value. Multivariate adjusted ORs (95% confidence intervals) for brachial-ankle pulse wave velocity across the uric acid quartiles were 2.642 (Q1, 1.095–6.3373), 1.00, 4.305 (Q3, 1.798–10.307), and 4.375 (Q4, 1.923–9.949), after adjusting for confounding variables.

Conclusion

Serum uric acid level has a J-shaped association with arterial stiffness in Korean postmenopausal women.

Evaluating risk factors for chronic kidney disease in pediatric patients with sickle cell anemia

BACKGROUND

Patients with sickle cell anemia (SCA) have an increased prevalence of nephropathy and mortality from chronic kidney disease (CKD).

METHODS

We evaluated the association of hyperuricemia and nocturnal hypertension with lower estimated glomerular filtration rate (eGFR) using cystatin-C in patients aged 10-21 years with the HbSS or HbSB0 form of the disease during a non-acute clinic visit. eGFR and uric acid measurements were obtained in 83 and 81 participants, respectively, and 24-h ambulatory blood pressure monitoring (ABPM) was performed in 44 participants. Annual testing included vital signs, complete blood count, comprehensive metabolic panel, medications, urine microalbumin/creatinine, and lactate dehydrogenase measurements. Hyperuricemia was defined as a uric acid level of ≥5.5 mg/dL. Nocturnal hypertension was defined as >25% of nocturnal readings at >95th percentile according to norms established by the American Heart Association Statement on ABPM in children and adolescents.

RESULTS

The mean eGFR was statistically significantly lower in patients with hyperuricemia than in those with normal uric acid levels (143 vs. 161 mL/min/1.73 m², respectively). Of the 44 participants for whom ABPM data were available, 14 (32%) had systolic nocturnal hypertension and 12 (27%) had diastolic nocturnal hypertension. The mean eGFR was statistically significantly lower in participants with nocturnal systolic and diastolic hypertension than in those with normal nocturnal blood pressure. In a regression model, nocturnal hypertension and hyperuricemia were associated with a lower eGFR.

CONCLUSIONS

Two risk factors for CKD, i.e., nocturnal hypertension and hyperuricemia, were associated with lower eGFR in older children and adolescent patients with SCA. Long-term studies on their association with progression to CKD in this population are warranted.

KEY POINT

Nocturnal hypertension and hyperuricemia are established risk factors for nephropathy in other diseases and may play a role in SCA nephropathy.

Association between serum uric acid and cardiovascular mortality and all-cause mortality: a cohort study

OBJECTIVE

Previous studies have reported the association among serum uric acid (SUA) levels and cardiovascular and all-cause mortality; however, the results have been inconsistent. The aim of this study was to investigate whether SUA is independently associated with cardiovascular and all-cause mortality in relatively healthy Korean adults.

METHODS

A total of 396 951 individuals were enrolled for the study between 2002 and 2012. About 39 991 participants were excluded for various reasons. All-cause and cardiovascular mortality data were collected. Cox proportional hazards models were used to estimate adjusted hazard ratios and 95% confidence intervals for all-cause and cardiovascular mortality according to baseline uric acid quintiles, and the third, middle SUA quintile was the reference group.

RESULTS

A total of 356 960 participants were considered to be eligible for the analysis, and median follow-up duration was 5.88 years. The lowest and highest quintiles of SUA were less than 5.2 and more than 7.1 mg/dl in men, and less than 3.5 and more than 5.0 mg/dl in women, respectively. A total of 2082 deaths (312 from cardiovascular disease and 1770 from other causes) occurred during follow-up. In the highest SUA group, adjusted hazard ratios for all-cause mortality were 1.24 (1.01, 1.51) in men and 1.04 (0.76, 1.42) in women, and for cardiovascular mortality were 1.15 (0.72, 1.83) in men and 1.69 (0.70, 4.04) in women after adjustment for various possible confounding factors.

CONCLUSION

In the current large relatively healthy population-based observational study, SUA showed no significant association with all-cause and cardiovascular mortality.

Effectiveness of dapagliflozin on vascular endothelial function and glycemic control in patients with early-stage type 2 diabetes mellitus: DEFENCE study

Background

Recent studies reported that sodium glucose cotransporter 2 (SGLT2) inhibitors can potentially reduce the risk of cardiovascular mortality in patients with type 2 diabetes mellitus (T2DM). However, there is little or no information on the therapeutic effects of SGLT2 inhibitors on the progression of atherosclerosis. This dapagliflozin effectiveness on vascular endothelial function and glycemic control (DEFENCE) study was designed to determine the effects of dapagliflozin, a SGLT2 inhibitor, on endothelial function in patients with early-stage T2DM.

Methods

DEFENCE is a prospective, randomized, open-label, blinded-endpoint, parallel-group, comparative clinical trial. Between October 2015 and August 2016, 80 T2DM patients treated with 750 mg of metformin (hemoglobin A1c ≥6.0 and <8.0%, n = 80) were enrolled and randomized to receive either 1500 mg/day metformin (the metformin group, n = 40), or 750 mg/day metformin supplemented with 5 mg/day dapagliflozin (the dapagliflozin group, n = 40), for 16 weeks. The primary endpoint was a change in flow-mediated dilation (FMD) from baseline to the end of the 16-week treatment period. The secondary outcomes include changes in indexes of glycemic control, lipid metabolism, and oxidative stress, body composition, and safety evaluation.

Results

Although FMD tended to improve only in the dapagliflozin group, ΔFMD was comparable between the two groups. Analysis of patients with HbA1c >7.0% showed significant improvement of FMD in the dapagliflozin group than metformin group (P < 0.05). HbA1c, fasting plasma glucose, plasma glucagon, and body weight significantly decreased in both groups. Interestingly, urine 8-hydroxy-2′-deoxyguanosin, a biomarker of oxidative stress, was significantly lower in the dapagliflozin group than metformin group at 16 weeks (P < 0.001).

Conclusions

Dapagliflozin add-on therapy to metformin for 16 weeks improved endothelial function, as assessed by FMD, in patients with inadequately controlled early-stage T2DM. Improvement in oxidative stress may contribute to the improvement in FMD.

Trial registration University Hospital Medical Information Network Clinical Trial Registry (UMIN000018754)

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-017-0564-0) contains supplementary material, which is available to authorized users.

EMPA-REG OUTCOME: The Nephrologist's Point of View

There is increasing evidence that sodium glucose cotransporter 2 (SGLT2) inhibitors have renoprotective effects, as demonstrated by the renal analyses from clinical trials including Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME), CANagliflozin Treatment And Trial Analysis versus SUlphonylurea (CANTATA-SU), and the dapagliflozin renal study. The potential mechanisms responsible are likely multifactorial, and direct renovascular and hemodynamic effects are postulated to play a central role. This report reviews the renal outcomes data from key SGLT2 inhibitor clinical trials, discusses the hypotheses for SGLT2 inhibitor-associated renoprotection, and considers the main renal safety issues associated with SGLT2 inhibitor treatment.

Cardiovascular Protection by Sodium Glucose Cotransporter 2 Inhibitors: Potential Mechanisms

The mechanism of action of empagliflozin in reducing the risk of adverse cardiovascular outcomes vs placebo in patients with type 2 diabetes mellitus and a high risk of cardiovascular disease in the Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME) trial is currently unknown. An antiatherosclerotic effect is considered unlikely given the speed of the observed decrease in cardiovascular mortality. Hemodynamic effects, such as reductions in blood pressure and intravascular volume, and involving osmotic diuresis, may provide a more plausible explanation. Metabolic effects, such as cardiac fuel energetics, and hormonal effects, such as increased glucagon release, may also contribute to the results observed during EMPA-REG OUTCOME. This review discusses the main hypotheses suggested to date.

EMPA-REG OUTCOME: The Nephrologist's Point of View

There is increasing evidence that sodium glucose cotransporter 2 (SGLT2) inhibitors have renoprotective effects, as demonstrated by the renal analyses from clinical trials including Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME), CANagliflozin Treatment And Trial Analysis versus SUlphonylurea (CANTATA-SU), and the dapagliflozin renal study. The potential mechanisms responsible are likely multifactorial, and direct renovascular and hemodynamic effects are postulated to play a central role. This report reviews the renal outcomes data from key SGLT2 inhibitor clinical trials, discusses the hypotheses for SGLT2 inhibitor-associated renoprotection, and considers the main renal safety issues associated with SGLT2 inhibitor treatment.

Cardiovascular Protection by Sodium Glucose Cotransporter 2 Inhibitors: Potential Mechanisms

The mechanism of action of empagliflozin in reducing the risk of adverse cardiovascular outcomes vs placebo in patients with type 2 diabetes mellitus and a high risk of cardiovascular disease in the Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME) trial is currently unknown. An antiatherosclerotic effect is considered unlikely given the speed of the observed decrease in cardiovascular mortality. Hemodynamic effects, such as reductions in blood pressure and intravascular volume, and involving osmotic diuresis, may provide a more plausible explanation. Metabolic effects, such as cardiac fuel energetics, and hormonal effects, such as increased glucagon release, may also contribute to the results observed during EMPA-REG OUTCOME. This review discusses the main hypotheses suggested to date.

Circulating TNF receptors predict cardiovascular disease in patients with chronic kidney disease

Cardiovascular disease (CVD) is the main public health problem in patients with chronic kidney disease (CKD); however, there is no established biomarker for predicting CVD morbidity and mortality in CKD. The aim of this study was to evaluate the role of circulating tumor necrosis factor receptors (cTNFRs) in predicting CVD risk in CKD patients.We prospectively recruited 984 patients with CKD from 11 centers between 2006 and 2012. The levels of cTNFR1 and cTNFR2 were determined by performing an enzyme-linked immunosorbent assay. During the mean follow-up period of 4 years, 36 patients experienced a CVD event. The median serum concentrations of cTNFR1 and cTNFR2 were 2703.4 (225.6-13,057.7) and 5661.0 (634.9-30,599.6) pg/mL, respectively, and the cTNFR1 level was closely correlated with the cTNFR2 level (r = 0.86, P < .0001). The urinary protein-to-creatinine ratio (UPCR) and estimated glomerular filtration rate (eGFR) were significantly correlated with the cTNFR2 level (r = 0.21 for UPCR, r = -0.67 for eGFR; P < .001 for all). Similar correlations were observed for serum cTNFR1 (r = 0.21 for UPCR, r = -0.75 for eGFR; P < .001 for all). In the Cox proportional hazard analyses, cTNFR1 (hazard ratio [HR] 2.506, 95% confidence interval [CI] 1.186-5.295, P = .016) and cTNFR2 (HR 4.156, 95% CI 1.913-9.030, P < .001) predicted CVD risk even after adjustment for clinical covariates, such as UPCR, eGFR, and high-sensitivity C-reactive protein. cTNFR1 and 2 are associated with CVD and other risk factors in CKD, independently of eGFR and UPCR. Furthermore, cTNFRs could be relevant predictors of CVD in CKD patients.

Trends in the levels of urine and serum creatinine: data from NHANES 2001-2014

Data from the National Health and Nutrition Examination Survey were used to study trends for urine and serum creatinine over 2001-2014 for those aged ≥20 years. In the absence of chronic kidney disease, levels of urine creatinine decreased for the total population, for those aged 20-29, 50-59, and ≥70 years, for males, and for Mexican Americans and other race/ethnicities. Levels of serum cotinine also exhibited a decreasing trend over 2001-2014 for the total population, for those aged 20-29 and 40-49 years, for females, and for non-Hispanic whites and Mexican Americans. In general, levels of serum creatinine and urine creatinine were positively correlated for chronic kidney disease stages 1-3 and negatively correlated for chronic kidney disease stages 4 and 5.

Serum Uric Acid and Progression of Kidney Disease: A Longitudinal Analysis and Mini-Review

Background

Increasing evidence supports the association between hyperuricemia and incident chronic kidney disease (CKD); however, there are conflicting data regarding the role of hyperuricemia in the progression of CKD. This study retrospectively assessed the longitudinal association between uric acid (UA) level and CKD progression in a Chinese population lived in Taiwan.

Methods

Patients with physician diagnosis of hyperuricemia or receiving urate-lowering therapy between 2003 and 2005 were identified in the electronic medical records (EMR) of a tertiary medical center and were followed up until December 31, 2011. Patients were divided into four UA categories at the cut-off 6, 8, and 10 mg/dL. CKD progression was estimated by the change of estimated glomerular filtration rate (eGFR) in the linear mixed models. Kidney failure was defined as an eGFR less than 15 mL/min/1.73 m² or requiring renal replacement therapy.

Results

A total of 739 patients were analyzed. In the full-adjusted model, patients with a baseline UA level ≥6 mg/dL had greater decline in eGFR ((β = -9.6, 95% CI -16.1, -3.1), comparing to those with a UA level less than 6 mg/dL. When stratifying patients into four UA categories, all three hyperuricemia categories (UA6-8, 8–10, ≥10 mg/dL) associated with a greater decline in eGFR over the follow-up period with an increasing dose-response, comparing to the lowest UA category. The risk of progression to renal failure increased 7% (hazard ratio 1.07, 95% CI 1.00, 1.14) for each 1mg/dL increase in baseline UA level. The influences of hyperuricemia on eGFR decline and the risk of kidney failure were more prominent in patients without proteinuria than those with proteinuria.

Conclusion

Our study showed a higher uric acid level is associated with a significant rapid decline in eGFR and a higher risk of kidney failure, particularly in patients without proteinuria. Our findings suggest hyperuricemia is a potential modifiable factor of CKD progression.

Sex-specific Relationship of Serum Uric Acid with All-cause Mortality in Adults with Normal Kidney Function: An Observational Study

OBJECTIVE

To explain the clinical effect of serum uric acid (SUA) levels as a risk factor for mortality, considering exclusion of kidney function.

METHODS

Participants aged over 40 years who underwent health checkups were recruited. Individuals with estimated glomerular filtrations rates < 60 ml/min/1.73 m² and who received laboratory study and colonoscopy on the same day were excluded.

RESULTS

SUA levels were higher in men than in women (5.7 ± 1.2 mg/dl for men and 4.2 ± 0.9 mg/dl for women, p < 0.001). During 12.3 ± 3.6 years of followup, 1402 deaths occurred among 27,490 participants. About 6.9% of men and 3.1% of women died. The overall mortality rate had a U-shaped association with SUA levels, a U-shaped association in men, and no association in women. There was a significant interaction of sex for the SUA-mortality association (p for interaction = 0.049); therefore, survival analysis was conducted by sex. In men, the lower SUA group had a higher mortality rate after adjustment (SUA ≤ 4.0 mg/dl, adjusted HR 1.413, 95% CI 1.158-1.724, p = 0.001) compared with the reference group (SUA 4.1-6.0 mg/dl). A higher SUA contributed to an insignificant increased mortality in men (> 8.0 mg/dl, adjusted HR 1.140, 95% CI 0.794-1.636, p = 0.479). Women failed to show any significant association between SUA and mortality.

CONCLUSION

This study provided novel evidence that SUA-mortality association differed by sex. We demonstrated that a lower SUA was an independent risk factor for all-cause mortality in men with normal kidney function.

Management of secondary hyperparathyroidism: how and why?

Secondary hyperparathyroidism (SHPT) is a common complication in chronic kidney disease. Currently, various treatment options are available, including vitamin D receptor activators, cinacalcet hydrochloride, and parathyroidectomy. These treatment options have contributed to the successful control of SHPT, and recent clinical studies have provided evidence suggesting that effective treatment of SHPT leads to improved survival. Although bone disease is the most widely recognized consequence of SHPT and remains a major target for treatment of SHPT, there is increasing evidence that parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23), both of which are markedly elevated in SHPT, have multiple adverse effects on extraskeletal tissues. These actions may lead to the pathological development of left ventricular hypertrophy, renal anemia, immune dysfunction, inflammation, wasting, muscle atrophy, and urate accumulation. Given that treatment of SHPT leads to decreases in both PTH and FGF23, these data provide an additional rationale for treating SHPT. However, definitive evidence is still lacking, and future research should focus on whether treatment of SHPT prevents the adverse effects of PTH and FGF23.

Empagliflozin as a new management strategy on outcomes in patients with type 2 diabetes mellitus

Patients with type 2 diabetes mellitus have an increased risk of cardiovascular (CV) complications. Although hyperglycaemia contributes to the pathogenesis of atherosclerosis and heart failure in these patients, glucose-lowering strategies did not have a significant effect on reducing CV risk, particularly in patients with a long duration of type 2 diabetes mellitus and prevalent CV disease (CVD). Sodium-glucose linked transporter-2 (SGLT2) inhibitors are a new class of anti-hyperglycaemic medications that increase glycaemic control via insulin-dependent mechanism of action associated with increased urinary glucose excretion.In this review, we present an analysis of the Empa-Reg Outcomes investigation, focussed on assessing the CV safety of empagliflozin, an inhibitor of SGLT2. We discuss the impressive results of trials that provide evidence on the cardiac and renal properties of empagliflozin. We present and analyse the current hypothesis on the mechanism of action of glucose-lowering medication, which has such a severe and complex impact on outcomes in patients with type 2 diabetes at high CV risk.

[Chronic kidney disease and dyslipidaemia]

Chronic kidney disease (CKD) has to be considered as a high, or even very high risk cardiovascular risk condition, since it leads to an increase in cardiovascular mortality that continues to increase as the disease progresses. An early diagnosis of CKD is required, together with an adequate identification of the risk factors, in order to slow down its progression to more severe states, prevent complications, and to delay, whenever possible, the need for renal replacement therapy. Dyslipidaemia is a factor of the progression of CKD that increases the risk in developing atherosclerosis and its complications. Its proper control contributes to reducing the elevated cardiovascular morbidity and mortality presented by these patients. In this review, an assessment is made of the lipid-lowering therapeutic measures required to achieve to recommended objectives, by adjusting the treatment to the progression of the disease and to the characteristics of the patient. In CKD, it seems that an early and intensive intervention of the dyslipidaemia is a priority before there is a significant decrease in kidney function. Treatment with statins has been shown to be safe and effective in decreasing LDL-Cholesterol, and in the reduction of cardiovascular events in individuals with CKD, or after renal transplant, although there is less evidence in the case of dialysed patients.

Relationship of serum uric acid and Killip class on mortality after acute ST-segment elevation myocardial infarction and primary percutaneous coronary intervention

BACKGROUND

There is conflicting information regarding the association between hyperuricemia and survival in STEMI patients. Our study examined the interaction between hyperuricemia and Killip class on mortality of STEMI patients.

METHODS

We analyzed 951 consecutive STEMI patients between February 2006 and September 2012. Hyperuricemia was defined as SUA of at least 7mg/dL in males and 6mg/dL in females. Killip class I patients were divided into hyperuricemia and normouricemia groups.

RESULTS

The Killip class I hyperuricemia and normouricemia groups had similar baseline and procedural characteristics, but the hyperuricemia group had significantly greater BMI, serum creatinine, and SUA, and a lower TIMI risk score (2, IQR: 1-4 vs. 3, IQR: 2-4, p=0.019). The hyperuricemia group also had greater 30-day and 1-year mortality rates (2.9% vs. 0.3%, p=0.022; 6.5% vs. 1.1%, p=0.002, respectively). However, hyperuricemia was not associated with mortality of patients in Killip classes II-IV or in the overall study population. Hyperuricemia was associated with increased mortality in subgroups of patients who were at least 65years-old, male, had BMI of 25kg/m² or less, were in Killip class I, without diabetes, and who did not receive intra-aortic balloon pump support. Hyperuricemia interacted with Killip class I in increasing the risk for 1-year mortality (p for interaction=0.038).

CONCLUSIONS

Hyperuricemia increased the 1-year mortality of STEMI patients in Killip class I, but not of patients in Killip classes II-IV. An interaction of hyperuricemia and Killip class significantly affects the mortality of STEMI patients.

Serum uric acid level and left ventricular hypertrophy in elderly male patients with nonvalvular atrial fibrillation

BACKGROUND AND AIMS

Recent studies have suggested that serum uric acid (SUA) induces oxidative stress and inflammation, which are involved in the mechanism of cardiac hypertrophy. In patients with atrial fibrillation (AF), comorbidity of left ventricular hypertrophy (LVH) exacerbates cardiac function. In this study, we investigated the association between SUA and cardiac hypertrophy in AF patients.

METHODS AND RESULTS

Initially, 1296 consecutive elderly patients (age >60) with nonvalvular AF were retrospectively selected from the inpatient clinic between January 2012 and April 2015. Demographic, clinical, and echocardiographic characteristics were carefully recorded. The final study population was 577 patients. The mean SUA level was significantly higher in patients with LVH than those without LVH. Compared with the non-LVH group, the LVH group was older, had a higher percentage of female patients, and had lower hemoglobin levels and estimated glomerular filtration rates. Patients in the LVH group also had a higher rate of coronary heart disease and fewer had history of radiofrequency ablation compared with the non-LVH group. In the hyperuricemia group, B-type natriuretic peptide levels, left atrial diameter, left ventricular mass index, and percentage of NYHA (New York Heart Association) class III/IV were significantly higher than the SUA normal group. Multivariate logistic regression analysis indicated the independent risk factors for LVH in elderly AF patients included SUA, age, male sex, the presence of coronary heart disease, and diuretic therapy. Subgroup analysis identified SUA as a significant risk factor associated with LVH in men.

CONCLUSIONS

SUA was independently associated with LVH in elderly male patients with nonvalvular AF.