Hyperuricemia as a Predictive Marker for Progression of Nephrosclerosis: Clinical Assessment of Prognostic Factors in Biopsy-Proven Arterial/Arteriolar Nephrosclerosis

Factors associated with early-onset intracranial aneurysms in patients with autosomal dominant polycystic kidney disease

BACKGROUND

Recently, the importance of attribute-based medicine has been emphasized. The effects of early-onset intracranial aneurysms on patients can be significant and long-lasting. Herein, we compared the factors associated with intracranial aneurysms in patients with autosomal dominant polycystic kidney disease (ADPKD) according to age categories (≥ 50 years, < 50 years).

METHODS

We included 519 ADPKD patients, with a median age of 44 years, estimated glomerular filtration rate of 54.5 mL/min/1.73 m2, and total follow-up duration of 3104 patient-years. Logistic regression analyses were performed to determine factors associated with intracranial aneurysms.

RESULTS

Regarding the presence of intracranial aneurysm, significant interactions were identified between the age category (age ≥ 50 years), female sex (P = 0.0027 for the interaction) and hypertension (P = 0.0074 for the interaction). Female sex and hypertension were associated with intracranial aneurysm risk factors only in patients aged ≥ 50 years. The presence of intracranial aneurysm was significantly associated with chronic kidney disease (CKD) stages 4-5 (odds ratio [OR] = 3.87, P = 0.0007) and family history of intracranial aneurysm or subarachnoid hemorrhage (OR = 2.30, P = 0.0217) in patients aged < 50 years. For patients aged ≥ 50 years, in addition to the abovementioned factors [OR = 2.38, P = 0.0355 for CKD stages 4-5; OR = 3.49, P = 0.0094 for family history of intracranial aneurysm or subarachnoid hemorrhage], female sex (OR = 4.51, P = 0.0005), and hypertension (OR = 5.89, P = 0.0012) were also associated with intracranial aneurysm.

CONCLUSION

Kidney dysfunction and family history of intracranial aneurysm or subarachnoid hemorrhage are risk factors for early-onset intracranial aneurysm. Patients aged < 50 years with a family history of intracranial aneurysm or subarachnoid hemorrhage or with CKD stages 4-5 may be at an increased risk of early-onset intracranial aneurysm.

Prevalence and clinical characteristics of hyperuricemia among patients with chronic kidney disease under haemodialysis in a tertiary care center: a cross-sectional study

Background

Hyperuricemia is common in chronic kidney disease patients. This study aimed to investigate the prevalence and clinical characteristics of hyperuricemia in patients with chronic kidney disease undergoing haemodialysis.

Materials and methods

This cross-sectional study was conducted among 104 patients with chronic kidney disease who visited the haemodialysis unit of a tertiary centre hospital from 11 September 2022, to 11 November 2022. A convenience sampling technique was used. The data were collected using a proforma form, entered into, and analyzed using the Statistical Package for Social Sciences version 21.

Results

The mean age group of the study participants was 54.02 ± 14.03 years, and around two-thirds were male (n=70, 67.3%). Almost half of the participants (50, 48.07%) had hyperuricemia with a mean uric acid level of 6.76 ± 2.62 mg/dl. The majority of the participants had associated hypertension (n=100, 96.2%). More than three-fourths of the respondents (83, 79.8%) had haemoglobin levels below the target range.

Conclusion

Nearly half of the study participants had hyperuricemia.

Prevalence and clinical association of hyperechoic crystal deposits on ultrasonography in patients with chronic kidney disease: a cross-sectional study from a single center

BACKGROUND

Hyperechoic crystal deposits can be detected in the kidney medulla of patients with gout by ultrasonography examination. Chronic kidney disease (CKD) is usually accompanied with hyperuricemia. Whether hyperechoic crystal deposition could be detected by ultrasonography in CKD patients, and its clinical association are unknown.

METHODS

Five hundred and fifteen consecutive CKD patients were included in this observational study. Clinical, biochemical and pathological data were collected and analyzed.

RESULTS

Altogether, 234 (45.4%) patients were found to have hyperuricemia and 25 patients (4.9%) had gout history. Hyperechoic crystal deposits in kidney medulla were found in forty-four (8.5%) patients, on ultrasonography. Compared with patients without hyperechoic crystal deposits, patients with deposits were more likely to be male, younger, with gout history and presenting with higher serum uric acid level, lower estimated glomerular filtration rate, lower urine pH, lower 24 h-urinary citrate and uric acid excretion, and with a higher percentage of ischemic nephropathy (all p < 0.05). On multivariable logistic analysis, the hyperechoic depositions were associated with age [0.969 (0.944, 0.994), p = 0.016], serum uric acid level [1.246 (1.027, 1.511), p = 0.026], Sqrt-transformed 24 h-urine uric acid excretion [0.923 (0.856, 0.996), p = 0.039], and ischemic nephropathy [4.524 (1.437, 14.239), p = 0.01], respectively.

CONCLUSIONS

Hyperechoic crystal deposition can be detected in kidney medulla by ultrasonography; in CKD patients their presence was associated with hyperuricemia as well as with ischemic nephropathy.

Association of blood pressure and hyperuricemia with proteinuria and reduced renal function in the general population

This study aimed to investigate the effect of hyperuricemia (HU) on the association of systolic blood pressure (SBP) with the prevalence of proteinuria and low estimated glomerular filtration rate (eGFR) in the general population. This cross-sectional study enrolled 24,728 Japanese individuals (11,137 men and 13,591 women) who underwent health checkups in 2010. The prevalence of proteinuria and low eGFR (< 60 mL/min/1.73 m2) among participants classified according to serum uric acid levels and SBP was compared. HU was defined as serum uric acid levels higher than the 75th percentile in male and female participants (> 7.2 and > 5.4 mg/dL, respectively). The odds ratio (OR) for proteinuria increased with elevated SBP. This trend was significantly evident in participants with HU. Moreover, there was an interactive effect of SBP and HU on the prevalence of proteinuria in the male (Pfor interaction = 0.04) and female (Pfor interaction = 0.04) participants. Next, we evaluated the OR for low eGFR (< 60 mL/min/1.73 m2) with and without proteinuria based on the presence of HU. The multivariate analysis revealed that the OR for low eGFR with proteinuria increased with elevated SBP, but that for low eGFR without proteinuria decreased. These trends of OR tended to be prevalent among those with HU. The association between SBP and the prevalence of proteinuria was more pronounced in participants with HU. However, the association between SBP and decreased renal function with and without proteinuria might be different regardless of HU.

IgA nephropathy associated with Crohn's disease

The relationship between IgA nephropathy (IgAN) and Crohn’s disease was reported. IgAN is the most common primary glomerulonephritis and one of the leading causes of chronic kidney disease and end-stage renal failure, and up to 50% of cases progressed to end-stage renal disease within 25 years after IgAN diagnosis. However, specific and effective therapeutic strategies are still lacking. In this review, we discuss the possibility of the mechanism involved in IgAN associated with Crohn’s disease based on the findings of basic and clinical studies. Although the etiology of IgAN associated with Crohn’s disease is not permanent and various factors are thought to be involved, the stabilization of the disease condition of Crohn’s disease is believed to help treat IgAN.

Uric acid accumulation in the kidney triggers mast cell degranulation and aggravates renal oxidative stress

The accumulation of uric acid (UA) in the body can lead to the occurrence of hyperuricemia or uric acid nephropathy. Mast cells (MCs) increase oxidative stress and release renin to promote the production of Ang II. The aim of this study was to investigate the effect of UA on MCs in rat kidneys and the association between MCs and renal injury. Our results show that UA accumulation in the kidney stimulated the degranulation of MCs and the release of renin to promote Ang II production, resulting in renal oxidative stress, mitochondrial structural damage, and microvascular system damage. The expression of urate-related transporters was regulated by the UA level and serum urinary toxins levels were substantially elevated in hyperuricemia. Administration of the MCs membrane stabilizer sodium cromoglycate (SCG) or the angiotensin receptor antagonist Valsartan decreased the production of renin and Ang II and relieved renal oxidative stress, mitigated mitochondrial structural damage and microvascular system damage, and promoted the excretion of UA and urinary toxins by increasing the expression of urate-related transporters. These results demonstrate that the accumulation of UA in the kidney can trigger the degranulation of MCs and promote the development of renal oxidative stress. Administration of SCG and Valsartan ameliorated UA-induced renal injury by inhibiting MCs degranulation and reducing renal oxidative stress by inhibiting renin and Ang II production and accelerating renal clearance of UA and uremic toxins.

Crohn's disease may promote inflammation in IgA nephropathy: a case-control study of patients undergoing kidney biopsy

Intestinal immunity has been closely associated with the pathogenesis and progression of renal diseases, a relationship known as the "gut-kidney axis." To determine the association between immunoglobulin A nephropathy (IgAN) and Crohn's disease (CD), a clinico-pathological study was performed on patients who had IgAN with CD (CD-IgAN) and without CD (NOS-IgAN). We enrolled 29 patients diagnosed with IgAN via renal biopsy at the Tokyo Yamate Medical Center from 2009 to 2017. The patients were divided into CD-IgAN (n = 18) and NOS-IgAN (n = 11) and evaluated for clinical and pathological findings. IgA subclasses and galactose-deficient IgA1 (Gd-IgA1) were examined via immunohistochemistry using formalin-fixed paraffin-embedded sections from renal biopsy. Our results showed no significant difference in the extent of mesangial IgA subclasses or Gd-IgA1 deposition according to the presence or absence of CD. Pathologically, however, those with CD-IgAN had remarkably higher percentage of global glomerulosclerosis and extent of interstitial fibrosis and tubular atrophy (IF/TA) compared to those with NOS-IgAN. Moreover, the extent of macrophage infiltration in the glomerulus and interstitium was significantly higher in CD-IgAN than in NOS-IgAN. Clinically, the CD-IgAN group had significantly worse responsiveness to steroid treatment compared to the NOS-IgAN group. In conclusion, the similar immunological characteristics of deposited IgA molecules in the glomeruli between the CD-IgAN and NOS-IgAN groups might suggest their etiological similarity. However, a renal pathology showing advanced glomerular and tubulointerstitial sclerosis accompanying increased macrophage infiltration and highly resistant clinical features in patients with CD-IgAN suggests that some pathophysiological factors in CD, including abnormal intestinal immunity, may promote and activate the inflammatory process in IgAN via undetermined mechanisms.

Urate-lowering therapy for CKD patients with asymptomatic hyperuricemia without proteinuria elucidated by attribute-based research in the FEATHER Study

Attribute-based medicine is essential for patient-centered medicine. To date, the groups of patients with chronic kidney disease (CKD) requiring urate-lowering therapy are clinically unknown. Herein, we evaluated the efficacy of febuxostat using a cross-classification, attribute-based research approach. We performed post hoc analysis of multicenter, randomized, double-blind, placebo-controlled trial data for 395 patients with stage 3 CKD and asymptomatic hyperuricemia. Participants were divided into febuxostat or placebo groups and subcohorts stratified and cross-classified by proteinuria and serum creatinine concentrations. In patients stratified based on proteinuria, the mean eGFR slopes were significantly higher in the febuxostat group than in the placebo group (P = 0.007) in the subcohort without proteinuria. The interaction between febuxostat treatment and presence of proteinuria in terms of eGFR slope was significant (P for interaction = 0.019). When cross-classified by the presence of proteinuria and serum creatinine level, the mean eGFR slopes significantly differed between the febuxostat and placebo groups (P = 0.040) in cross-classified subcohorts without proteinuria and with serum creatinine level ≥ median, but not in the cross-classified subcohorts with proteinuria and serum creatinine level < median. Febuxostat mitigated the decline in kidney function among stage 3 CKD patients with asymptomatic hyperuricemia without proteinuria.

Uric Acid and Impairment of Renal Function in Non-diabetic Hypertensive Patients

Hyperuricemia is a risk factor for renal impairment. However, investigations focusing on patients with hypertension are limited and inconsistent. A single-center prospective cohort study of 411 Han Chinese non-diabetic hypertensive patients was conducted in Taiwan. The mean age of the participants was 62.0 ±14.4 years. The baseline estimated glomerular filtration rate and uric acid level were 86 mL/min/1.73 m² and 6.2 mg/dL, respectively. All patients underwent serum biochemistry tests for creatinine levels every 3 months. Renal events were defined as >25% and >50% decline in estimated glomerular filtration rate. During an average follow-up period of 4.7 ± 2.9 years (median 4.0 years), a >25 and >50% decline in estimated glomerular filtration rate was noted in 52 and 11 patients, respectively. The multivariate Cox regression analysis revealed that a baseline uric acid level ≥8.0 mg/dL increased the risk of >25% decline (hazard ratio: 3.541; 95% confidence interval: 1.655–7.574, P = 0.001) and >50% decline (hazard ratio: 6.995; 95% confidence interval: 1.309–37.385, P = 0.023) in estimated glomerular filtration rate. Similarly, a baseline uric acid level ≥7.5 mg/dL was independently associated with >25% decline (hazard ratio: 2.789; 95% confidence interval: 1.399–5.560, P = 0.004) and >50% decline (hazard ratio: 6.653; 95% confidence interval: 1.395–31.737, P = 0.017). However, this was not demonstrated at baseline uric acid level ≥7.0 mg/dL. Our study suggests that hyperuricemia is an independent risk factor for the decline in renal function in patients with hypertension. Uric acid level ≥7.5 mg/dL may be considered as the optimal cutoff value for clinical practice in predicting the development of renal impairment.

Normotensive and hypertensive Immunoglobulin a nephropathy with ischemic renal injury: clinicopathological characteristics and prognosis

OBJECTIVES

This study aimed to investigate the clinicopathological characteristics and prognosis of normotensive and hypertensive IgAN patients with ischemic renal injury.

METHODS

A total of 344 cases of IgAN with ischemic renal injury were included in the study, including 99 normotensive IgAN patients (28.8%) and 245 hypertensive IgAN patients (71.2%). In addition, 467 IgAN patients without ischemic renal injury were included as controls, including 205 normotensive patients and 262 hypertensive patients. Clinicopathological and prognostic data were collected and analyzed.

RESULTS

Compared with patients without ischemic renal injury, IgAN patients with ischemic renal injury displayed a higher proportion of hypertention, a higher proportion of ischemic glomerulosclerosis, tubular atrophy/interstitial fibrosis and vascular lesions (all p < .05). There was no significant difference in cumulative survival between the normotensive IgAN patients groups (Log-rank χ² = 0.479; p = .489). Furthermore, ischemic renal injury was not a risk factor for end-point events in normotensive IgAN patients (HR = 1.103; 95% CI: 0.279-4.365; p = .889). There was lower cumulative survival in hypertensive IgAN patients with ischemic renal injury (Log-rank χ² = 11.352, p = .001). Moreover, ischemic renal injury was a risk factor for end-point events in hypertensive IgAN patients (HR = 1.889; 95% CI: 1.124-3.178; p = .016).

CONCLUSIONS

Ischemic renal injury can occur in normotensive IgAN patients. Although the pathological changes may not affect the long-term prognosis of normotensive IgAN patients, the prognosis for hypertensive IgAN patients remains poor. Therefore, increased attention should be paid to the clinical management of ischemic lesions in hypertensive IgAN patients.

Hyperuricemia, the heart, and the kidneys - to treat or not to treat?

Background

Hyperuricemia is a state in which the serum levels of uric acid are elevated. As such it has a pronounced effect on vascular and renal function with their consequences, while also showing some antioxidant effects that show to be beneficial.

Summary

Hyperuricemia has shown to have a J-shaped relationship with mortality, is frequently associated with development and progression of heart and kidney disease, and is correlated with malnutrition-inflammation-atherosclerosis syndrome, although several Mendelian studies have failed to show an association with morbidity and mortality. Hyperuricemia is usually associated with gout flares and tophi development but can also present as asymptomatic hyperuricemia. It is still uncertain whether asymptomatic hyperuricemia is an independent risk factor for cardiovascular or renal disease and as such its treatment is questionable.

Key messages

Some possible tools for future decision making are the use of noninvasive techniques such as pulse wave analysis, urinary sediment analysis, and joint ultrasound, which could help identify individuals with asymptomatic hyperuricemia that could benefit from urate lowering therapy most.

Characteristics, Comorbidities, and Potential Consequences of Uncontrolled Gout: An Insurance-Claims Database Study

INTRODUCTION

Gout is a common, progressive, systemic inflammatory arthritis caused by hyperuricemia. Current guidelines recommend that serum uric acid (sUA) levels be maintained below 6.0 mg/dl to minimize acute gout attacks, tophi development, and long-term joint and organ damage. This study examined the influence of uncontrolled gout on post-diagnosis comorbidities and medication use.

METHODS

The Humana Research Database (2007-2016, commercial insurance and Medicare) was searched (PearlDiver tool) for patients who had a gout diagnosis code, claims data for at least 6 months before and after diagnosis, and at least 90 days of continuous urate-lowering therapy within 1 year of diagnosis. Patients with controlled (all sUA measurements < 6.0 mg/dl) and uncontrolled (all sUA measurements ≥ 8.0 mg/dl) gout were further examined and compared to better understand the influence of uncontrolled gout on post-diagnosis comorbidities, medication use, and reasons for seeking medical care.

RESULTS

A total of 5473 and 1358 patients met inclusion and classification criteria for the controlled and uncontrolled groups, respectively. Identified comorbidities in both groups included hypertension, hyperlipidemia, diabetes, cardiovascular disease, and chronic kidney disease (CKD). However, the uncontrolled group was more likely to have diabetes, CKD, and cardiovascular disease (including heart failure and atrial fibrillation). Additionally, CKD tended to be more advanced in the uncontrolled gout population (Stage 4-5: 34.6 vs. 22.2%). Overall opioid use was higher in uncontrolled patients.

CONCLUSIONS

The current study identified differences between controlled and uncontrolled gout patients, including usage of medication, severity of CKD, and prevalence of CKD, diabetes, and heart disease.

Sex Differences in Time-Series Changes in Pseudo-R2 Values Regarding Hyperuricemia in Relation to the Kidney Prognosis

Studies on sex differences in time-series changes in pseudo-R² values regarding hyperuricemia (HU) in relation to the kidney prognosis among patients with chronic kidney disease (CKD) are scant. The kidney prognosis was evaluated in 200 patients with CKD (median follow-up, 12.3 years). Survival analyses and logistic regression analyses were conducted, generating time-series pseudo-R² values. We used four definitions of HU according to serum uric acid (SUA) levels (HU6, SUA ≥ 6.0 mg/dL; HU7, SUA ≥ 7.0 mg/dL; HU8, SUA ≥ 8.0 mg/dL) and antihyperuricemic agent use to calculate the mean and percentage of the change in pseudo-R² values from the 6th year until the end of the study (6Y–End Mean and 6Y–End Change, respectively). The multivariable Cox regression analysis showed that HU7 was significantly associated with kidney outcomes. When stratified by sex, the 6Y–End Mean was clearly higher in women than in men for all HU definitions, with the highest value (0.1755) obtained for HU7 in women. The pseudo-R² values for HU6 in women showed an increasing pattern, with a 6Y–End Change of 11.4%/year. Thus, it may be clinically meaningful to consider sex differences in the time-series pseudo-R² values regarding HU and kidney outcomes.

Prevalences of hyperuricemia and electrolyte abnormalities in patients with chronic kidney disease in Japan: A nationwide, cross-sectional cohort study using data from the Japan Chronic Kidney Disease Database (J-CKD-DB)

BACKGROUND

The Japan Chronic Kidney Disease Database (J-CKD-DB) is a nationwide clinical database of patients with chronic kidney disease (CKD) based on electronic health records. The objective of this study was to assess the prevalences of hyperuricemia and electrolyte abnormalities in Japanese patients with CKD.

METHODS

In total, 35,508 adult outpatients with estimated glomerular filtration rates of 5-60 ml/min/1.73 m2 in seven university hospitals were included this analysis. The proportions of patients with CKD stages G3b, G4, and G5 were 23.5%, 7.6%, and 3.1%, respectively.

RESULTS

Logistic regression analysis showed that prevalence of hyperuricemia was associated with CKD stages G3b (adjusted odds ratio [95% confidence interval]: 2.12 [1.90-2.37]), G4 (4.57 [3.92-5.32]), and G5 (2.25 [1.80-2.80]). The respective prevalences of hyponatremia, hypercalcemia, hyperphosphatemia, and narrower difference between serum sodium and chloride concentrations were elevated in patients with CKD stages G3b, G4, and G5, compared with those prevalences in patients with CKD stage G3a. The prevalences of hyperkalemia were 8.3% and 11.6% in patients with CKD stages G4 and G5, respectively. In patients with CKD stage G5, the proportions of patients with optimal ranges of serum uric acid, potassium, corrected calcium, and phosphate were 49.6%, 73.5%, 81.9%, and 56.1%, respectively.

CONCLUSIONS

We determined the prevalences of hyperuricemia and electrolyte abnormalities in Japanese patients with CKD using data from a nationwide cohort study.

Assessment of the efficacy of hemodialysis on uric acid clearance in a sub-Saharan African population at the end stage kidney disease

Background

Uricemia dramatically rises with the stage of chronic kidney disease (CKD) and correlates with its mortality. Hemodialysis (HD) being the most used treatment at the end stage in sub-Saharan Africa, we sought to evaluate its efficacy on the clearance of uric acid (UAc) when used alone and twice per week.

Methods

A cross-sectional study of all consenting patients with CKD stage 5 recruited at random during HD sessions in a reference Centre in Cameroon from January to April 2017. We collected socio-demographic data, relevant clinical information, HD related variables, and measured serum uric acid (SUA) levels before and after the dialysis to assess the uric acid clearance. A clearance between 65 and 80% and above 80% was considered as low and good efficacy of HD respectively. Statistical analysis was performed using SPSS version 21.0. Factors associated with HD efficacy were assessed using Fisher’s exact test and are presented with their odds ratios (OR) and 95% confidence levels.

Results

One hundred four patients (53 females) were included. The mean age was 49.9 ± 13.3 years. Hypertension (25%) and chronic glomerulonephritis (16%) were the main suspected etiologies of CKD. The median time on renal replacement therapy by HD was 3 years [1; 6]. The prevalence of hyperuricemia was 81.9%. The means of SUA levels were 78.8 ± 13.8 mg/L and 26.4 ± 6.6 mg/L respectively before and after dialysis. Mean SUA clearance was 66% ± 10%. The efficacy of HD on UAc was moderate in 92 (63.9%) and good in 2 (1.4%) patients. Excess weight (OR 0.4 [0.2; 0.9]) and Kt/Vurea < 1.2 (OR 0.1 [0.04; 0.2]) significantly reduces the efficacy of HD.

Conclusion

HD used alone for 2 sessions per week has a moderate efficacy on uric acid clearance in CKD. Therefore, we should improve the Kt/V (> 1.2), and combine HD to uric acid lowering drugs and diet modifications to increase its efficacy.

Time-averaged proteinuria during follow-up and renal prognosis in patients with biopsy-proven benign nephrosclerosis

BACKGROUND

Heavy proteinuria at diagnostic renal biopsy has been reported as an independent risk factor for deteriorating renal function in benign nephrosclerosis (BNS). However, studies investigating the relationship between the amount of proteinuria during follow-up and long-term renal prognosis in BNS are limited. This study aimed to assess the relationship between time-averaged proteinuria (TAP) and renal prognosis in BNS.

METHODS

The study participants included 98 patients with biopsy-proven BNS (average age 52 ± 13 years, estimated glomerular filtration rate (eGFR) 53 ± 25 ml/min/1.73 m², urine protein excretion at baseline 1.34 ± 1.30 g/gCr) from the Jikei University Hospital. Multivariate analysis was used to investigate the effects of TAP and other clinicopathological findings on the risk for renal outcome in biopsy-proven BNS (a 30% decline in eGFR from baseline or end-stage renal disease). Proteinuria was measured every 6 months and the mean value was used as an indicator of TAP.

RESULTS

The average observation period was 56 ± 43 months. In the unadjusted model, higher levels of TAP and urinary protein at baseline, glomerulosclerosis, and tubulointerstitial damage were associated with renal prognosis. The adjusted model demonstrated a significant association between TAP and renal outcomes (hazard ratio 5.45, 95% confidence interval 3.02-10.7), which was independent of higher baseline proteinuria, glomerulosclerosis, and tubulointerstitial damage.

CONCLUSIONS

TAP is an independent risk factor for renal prognosis in patients with BNS, indicating the significance of urinary protein excretion during follow-up for the progression of BNS. Clinicians should understand the importance of follow-up evaluation for proteinuria in patients with BNS.

Clinicopathological predictors for progression of chronic kidney disease in nephrosclerosis: a biopsy-based cohort study

BACKGROUND

Biopsy-based studies on nephrosclerosis are lacking and the clinicopathological predictors for progression of chronic kidney disease (CKD) are not well established.

METHODS

We retrospectively assessed 401 patients with biopsy-proven nephrosclerosis in Japan. Progression of CKD was defined as new-onset end-stage renal disease, decrease of estimated glomerular filtration rate (eGFR) by  ≥50% or doubling of serum creatinine, and the sub-distribution hazard ratio (SHR) with 95% confidence interval (CI) for CKD progression was determined for various clinical and histological characteristics in competing risks analysis. The incremental value of pathological information for predicting CKD progression was assessed by calculating Harrell's C-statistics, the Akaike information criterion (AIC), net reclassification improvement and integrated discrimination improvement.

RESULTS

During a median follow-up period of 5.3 years, 117 patients showed progression of CKD and 10 patients died before the defined kidney event. Multivariable sub-distribution hazards model identified serum albumin (SHR 0.48; 95% CI 0.35-0.67), hemoglobin A1c (SHR 0.71; 95% CI 0.54-0.94), eGFR (SHR 0.98; 95% CI 0.97-0.99), urinary albumin/creatinine ratio (UACR) (SHR 1.18; 95% CI 1.08-1.29), percentage of segmental/global glomerulosclerosis (%GS) (SHR 1.01; 95% CI 1.00-1.02) and interstitial fibrosis and tubular atrophy (IFTA) (SHR 1.52; 95% CI 1.20-1.92) as risk factors for CKD progression. The C-statistic of a model with only clinical variables was improved by adding %GS (0.790 versus 0.796, P < 0.01) and IFTA (0.790 versus 0.811, P < 0.01). The reclassification statistic was also improved after adding the biopsy data to the clinical data. The model including IFTA was superior, with the lowest AIC.

CONCLUSIONS

The study implies that in addition to the traditional markers of eGFR and UACR, we may explore the markers of serum albumin and hemoglobin A1c, which are widely available but not routinely measured in patients with nephrosclerosis, and the biopsy data, especially the data on the severity of interstitial damage, for the better prediction of CKD progression in patients with nephrosclerosis.

The role of oxidative stress-mediated apoptosis in the pathogenesis of uric acid nephropathy

Objective: By copying the uric acid nephropathy rat model, the oxidative stress injury of mitochondria was caused in renal tubular epithelial cells and the relationship between the injury and the induction of cell apoptosis was identified.

Methods: All rats were randomly divided into NC (normal control, NC) group, HUA (high uric acid, HUA) group and GSH (reductive glutathione, GSH) group. The values were quantitatively tested in the kidney tissues, including 24-h urinary protein quantity, serum creatinine, blood uric acid, the MDA (malondialdehyde, MDA) and SOD (superoxide dismutase, SOD) oxidative stress indicators. The expression of p53, Bax and caspase-9/-3 were detected by immunoblotting. TUNEL assays were used to detect the apoptosis of renal tubular epithelial cells.

Result: In HUA and GSH groups, the 24-h urinary protein(24UTP), serum creatinine, and blood uric acid increased gradually with the increase of the replication cycle and the increase was significant compared to the NC group (p < .05). Compared to the NC group, MDA increased whereas SOD decreased. The expression of apoptotic proteins, such as p53, Bax, and caspase-9/-3 in the mitochondria was significantly different (p < .05). TUNEL assay revealed that the renal tubular epithelial cells in HUA group were largely apoptotic, whereas the GSH group improved significantly.

Conclusion: Mitochondria incurred the substantial damage due to being in a state of oxidative stress, which was the primary cause of apoptosis in the renal tubule epithelial cells. GSH exhibited the effective resistance to the influence of oxidative stress and can restore the damage in the renal tubular epithelial cells.

Treatment of asymptomatic hyperuricemia complicated by renal damage: a controversial issue

The prevalence of asymptomatic HUA is increasing year after year. HUA is a risk factor for the occurrence and development of renal diseases. However, the role of urate-lowering therapy in asymptomatic HUA complicated by renal damage is still controversial. In some experiments, the treatment of asymptomatic HUA complicated by renal damage may delay the progression of kidney damage. In addition, there is increasing evidence, suggesting that elevated serum uric acid is an independent risk factor for kidney disease. However, in other studies, uric acid-lowering therapy did not improve renal function, and uric acid levels could not be used as an independent predictor for CKD development. Further experimental studies are needed to determine the starting threshold and target value of asymptomatic HUA complicated by renal damage. At the same time, confirmation of the benefits of urate-lowering therapy for kidneys requires studies with larger samples and high-quality RCTs.

Association of renal arteriosclerosis and hypertension with renal and cardiovascular outcomes in Japanese type 2 diabetes patients with diabetic nephropathy

AIMS/INTRODUCTION

The present retrospective study investigated the impact of renal arteriosclerosis (AS) and hypertension (HT) on long-term renal and cardiovascular outcomes in Japanese type 2 diabetes patients with biopsy-proven diabetic nephropathy.

MATERIALS AND METHODS

A total of 185 patients were enrolled. Patients were divided into four groups stratified by renal AS status and the presence of HT. The outcomes for this study were the first occurrence of renal events (a need for dialysis or a 30% decline in estimated glomerular filtration rate from baseline) and cardiovascular events (cardiovascular death, non-fatal myocardial infarction, coronary intervention or non-fatal stroke).

RESULTS

The proportion of renal AS scores ≥1 was 88.3% among patients with normal-range blood pressure (BP) and 95.4% among patients with HT. During a mean follow-up period of 7.6 years, 129 episodes of renal composite events and 55 episodes of cardiovascular events were observed. Compared with patients with no renal AS and normal-range BP, a renal AS score ≥1 increased the risk of renal composite events with a multivariable-adjusted hazard ratio of 3.21 (95% confidence interval [95% CI] 1.27-8.14) in patients with normal-range BP and 4.99 (95% CI 1.98-12.54) in patients with HT, whereas renal AS score ≥1 increased the risk of cardiovascular events with a multivariable-adjusted hazard ratio of 6.06 (95% CI 1.24-29.61) in patients with normal-range BP and 10.02 (95% CI 1.92-52.39) in patients with HT.

CONCLUSIONS

Renal AS was associated with increasing risks for renal composite events and cardiovascular events in both normal-range BP and HT. The risks of renal composite events and cardiovascular events were the highest in both renal AS and HT.

Gout and hyperuricaemia in the USA: prevalence and trends

Objectives

Several recent observations have suggested that the prevalence of gout may be increasing worldwide, but there are no recent data from the USA. We analysed the prevalence of hyperuricaemia and gout in the US population from 2007–08 to 2015–16.

Methods

We studied adults ⩾20 years of age from the National Health and Nutrition Examination Survey from 2007–08 to 2015–16. Persons with gout were identified from the home interview question ‘Has a doctor or other health professional ever told you that you had gout?’ Hyperuricaemia was defined as a serum urate level >0.40 mmol/l (6.8 mg/dl) (supersaturation levels at physiological temperatures and pH).

Results

In 2015–16, the overall prevalence of gout among US adults was 3.9%, corresponding to a total affected population of 9.2 million. Hyperuricaemia (>0.40 mmol/l or 6.8 mg/dl) was seen in 14.6% of the US population (estimated 32.5 million individuals). No significant trends were identified in the age-adjusted prevalence of gout and hyperuricaemia. Statistical comparisons between 2007–08 and 2015–16 age-adjusted rates were not significant.

Conclusion

While the age-adjusted prevalence of gout and hyperuricaemia has remained unchanged in the most recent decade from 2007–08 to 2015–16, the estimated total number of persons with self-reported gout has increased from 8.3 million to 9.2 million. The age-adjusted prevalence of hyperuricaemia has declined slightly, but the total number of affected individuals is virtually identical (32.5 million in 2015–16 compared with 32.1 million in 2007–08).

Asymptomatic hyperuricemia and cardiovascular mortality in patients with chronic kidney disease who progress to hemodialysis

PURPOSE

Hyperuricemia has been associated with higher mortality in the general population, but less is known about CKD patients. The aim of our study was to determine the impact of elevated serum uric acid on cardiovascular mortality of CKD patients who later progress to hemodialysis.

METHODS

In this retrospective study, 120 CKD patients (entire population of patients with ESKD on January 1st, 2012) were observed from their first visit at the Nephrology outpatient clinic, while transitioning to hemodialysis, and until their death or January 1, 2016. After non-cardiovascular death exclusion, 83 CKD patients (33 female, 50 male) were left for further analysis. The average time of observation was 8.8 ± 4.2 years. Serum uric acid was measured regularly (every 3 months). No patients were treated for hyperuricemia. Mean uric acid of 420 µmol/L was set as a cut-off between normouricemic and hyperuricemic patients as per the laboratory's reference values. Survival rates were analyzed using Kaplan-Meier survival curves. Three Cox regression models were used to assess the influence of uric acid on survival.

RESULTS

Mean uric acid was 379.8 ± 71.6 µmol/L (range 220-574). Sixty-three (75.9%) patients were normouricemic and 20 (24.1%) were hyperuricemic. Cholesterol was the only variable to show statistically significant difference (p = 0.004) between the groups. Bivariate analysis revealed an association between death and age, hyperuricemia, arterial hypertension, and history of cardiovascular disease. Kaplan-Meier survival analysis showed higher risk of cardiovascular death for hyperuricemic patients (log rank test; p < 0.0005). In Cox regression models, hyperuricemia remained a predictor of cardiovascular mortality (SE = 0.500, Exp(B) = 14.120, 95% CI 5.297-37.640) in our patients next to age and arterial hypertension.

CONCLUSION

The results indicate an association between hyperuricemia and cardiovascular mortality in CKD patients who transition to hemodialysis.