Insulin resistance, kidney outcomes and effects of the endothelin receptor antagonist atrasentan in patients with type 2 diabetes and chronic kidney disease.

BACKGROUND: Insulin resistance (IR) is a pathophysiologic hallmark of type 2 diabetes and associated with the presence of chronic kidney disease (CKD). Experimental studies suggest that endothelin-1 increases IR. We assessed the association between IR and cardio-renal outcomes and the effect of the selective endothelin receptor antagonist atrasentan on IR in patients with type 2 diabetes and CKD. METHODS: We used data from the RADAR and SONAR trials that recruited participants with type 2 diabetes and CKD [eGFR 25-75 mL/min/1.73 m², urine albumin-to-creatinine ratio of 300-5000 mg/g]. IR was calculated using the homeostatic model assessment (HOMA-IR). The association between HOMA-IR and the pre-specified cardio-renal outcomes was assessed using multivariable Cox proportional hazards regression, and effects of atrasentan on HOMA-IR by a linear mixed effect model. RESULTS: In the SONAR trial, each log-unit increase in HOMA-IR was associated with an increased risk of the composite cardio-renal outcome [hazard ratio 1.32 (95%CI 1.09,1.60; p = 0.004)], kidney outcome [hazard ratio 1.30 (95%CI 1.00,1.68; p-value = 0.048)], and the kidney or all-cause mortality outcome [hazard ratio 1.25 (95%CI 1.01,1.55; p-value = 0.037)]. After 12 weeks treatment in the RADAR trial (N = 123), atrasentan 0.75 mg/day and 1.25 mg/day compared to placebo reduced HOMA-IR by 19.1 (95%CI -17.4, 44.3) and 26.7% (95%CI -6.4, 49.5), respectively. In the SONAR trial (N = 1914), atrasentan 0.75 mg/day compared to placebo reduced HOMA-IR by 9.6% (95%CI 0.6, 17.9). CONCLUSIONS: More severe IR is associated with increased risk of cardio-renal outcomes. The endothelin receptor antagonist atrasentan reduced IR. TRIAL REGISTRATION: RADAR trial (Reducing Residual Albuminuria in Subjects With Diabetes and Nephropathy With AtRasentan): NCT01356849. SONAR trial (The Study Of Diabetic Nephropathy With AtRasentan) NCT01858532.

Epidemiology of the diabetes-cardio-renal spectrum: a cross-sectional report of 1.4 million adults.

BACKGROUND: Type-2 diabetes (T2D), chronic kidney disease, and heart failure (HF) share epidemiological and pathophysiological features. Although their prevalence was described, there is limited contemporary, high-resolution, epidemiological data regarding the overlap among them. We aimed to describe the epidemiological intersections between T2D, HF, and kidney dysfunction in an entire database, overall and by age and sex. METHODS: This is a cross-sectional analysis of adults ≥ 25 years, registered in 2019 at Maccabi Healthcare Services, a large healthcare maintenance organization in Israel. Collected data included sex, age, presence of T2D or HF, and last estimated glomerular filtration rate (eGFR) in the past two years. Subjects with T2D, HF, or eGFR < 60 mL/min/1.73 m2 were defined as within the diabetes-cardio-renal (DCR) spectrum. RESULTS: Overall, 1,389,604 subjects (52.2% females) were included; 445,477 (32.1%) were 25- < 40 years, 468,273 (33.7%) were 40- < 55 years, and 475,854 (34.2%) were ≥ 55 years old. eGFR measurements were available in 74.7% of the participants and in over 97% of those with T2D or HF. eGFR availability increased in older age groups. There were 140,636 (10.1%) patients with T2D, 54,187 (3.9%) with eGFR < 60 mL/min/1.73m2, and 11,605 (0.84%) with HF. Overall, 12.6% had at least one condition within the DCR spectrum, 2.0% had at least two, and 0.23% had all three. Cardiorenal syndrome (both HF and eGFR < 60 mL/min/1.73m2) was prevalent in 0.40% of the entire population and in 2.3% of those with T2D. In patients with both HF and T2D, 55.2% had eGFR < 60 mL/min/1.73m2 and 15.8% had eGFR < 30 mL/min/1.73m2. Amongst those within the DCR spectrum, T2D was prominent in younger participants, but was gradually replaced by HF and eGFR < 60 mL/min/1.73m2 with increasing age. The congruence between all three conditions increased with age. CONCLUSIONS: This large, broad-based study provides a contemporary, high-resolution prevalence of the DCR spectrum and its components. The results highlight differences in dominance and degree of congruence between T2D, HF, and kidney dysfunction across ages.

Effects of Vitamin D Receptor Activation and Dietary Sodium Restriction on Residual Albuminuria in CKD: The ViRTUE-CKD Trial.

Reduction of residual albuminuria during single-agent renin-angiotensin-aldosterone blockade is accompanied by improved cardiorenal outcomes in CKD. We studied the individual and combined effects of the vitamin D receptor activator paricalcitol (PARI) and dietary sodium restriction on residual albuminuria in CKD. In a multicenter, randomized, placebo (PLAC)-controlled, crossover trial, 45 patients with nondiabetic CKD stages 1-3 and albuminuria >300 mg/24 h despite ramipril at 10 mg/d and BP<140/90 mmHg were treated for four 8-week periods with PARI (2 µg/d) or PLAC, each combined with a low-sodium (LS) or regular sodium (RS) diet. We analyzed the treatment effect by linear mixed effect models for repeated measurements. In the intention-to-treat analysis, albuminuria (geometric mean) was 1060 (95% confidence interval, 778 to 1443) mg/24 h during RS + PLAC and 990 (95% confidence interval, 755 to 1299) mg/24 h during RS + PARI (P=0.20 versus RS + PLAC). LS + PLAC reduced albuminuria to 717 (95% confidence interval, 512 to 1005) mg/24 h (P<0.001 versus RS + PLAC), and LS + PARI reduced albuminuria to 683 (95% confidence interval, 502 to 929) mg/24 h (P<0.001 versus RS + PLAC). The reduction by PARI beyond the effect of LS was nonsignificant (P=0.60). In the per-protocol analysis restricted to participants with ≥95% compliance with study medication, PARI did provide further albuminuria reduction (P=0.04 LS + PARI versus LS + PLAC). Dietary adherence was good as reflected by urinary excretion of 174±64 mmol Na+ per day in the combined RS groups and 108±61 mmol Na+ per day in the LS groups (P<0.001). In conclusion, moderate dietary sodium restriction substantially reduced residual albuminuria during fixed dose angiotensin-converting enzyme inhibition. The additional effect of PARI was small and nonsignificant.

Association of Skin Autofluorescence Levels With Kidney Function Decline in Patients With Peripheral Artery Disease.

OBJECTIVE: Skin autofluorescence (SAF), a measure of advanced glycation end product accumulation, is associated with kidney function. We investigated the association of SAF with rate of kidney function decline in a cohort of patients with peripheral artery disease. APPROACH AND RESULTS: We performed a post hoc analysis of an observational longitudinal cohort study. We included 471 patients with peripheral artery disease, and SAF was measured at baseline. Primary end point was rate of estimated glomerular filtration rate (eGFR) decline. Secondary end points were incidence of eGFR <60 and <45 mL/min/1.73 m(2) and rapid eGFR decline, defined as a decrease in eGFR of >5 mL/min/1.73 m(2)/y. During a median follow-up of 3 years, the mean change in eGFR per year was -1.8±4.4 mL/min/1.73 m(2)/y. No significant difference in rate of eGFR decline was observed per 1 arbitrary unit increase in SAF (-0.1 mL/min/1.73 m(2)/y; 95% confidence interval, -0.7 to 0.5; P=0.8). Analyses of the secondary end points showed that there was an association of SAF with incidence of eGFR <60 and <45 mL/min/1.73 m(2) (hazard ratio, 1.54; 95% confidence interval, 1.13-2.10; P=0.006 and hazard ratio, 1.76; 95% confidence interval, 1.20-2.59; P=0.004, respectively), but after adjustment for age and sex, significance was lost. There was no association of SAF with rapid eGFR decline. CONCLUSIONS: In conclusion, in this cohort of patients with peripheral artery disease, elevated SAF was associated with lower baseline eGFR. Although SAF has previously been established as a predictor for cardiovascular disease and mortality, it did not predict the rate of kidney function decline during follow-up in this study.

Bardoxolone methyl in type 2 diabetes and stage 4 chronic kidney disease.

BACKGROUND: Although inhibitors of the renin-angiotensin-aldosterone system can slow the progression of diabetic kidney disease, the residual risk is high. Whether nuclear 1 factor (erythroid-derived 2)-related factor 2 activators further reduce this risk is unknown. METHODS: We randomly assigned 2185 patients with type 2 diabetes mellitus and stage 4 chronic kidney disease (estimated glomerular filtration rate [GFR], 15 to <30 ml per minute per 1.73 m(2) of body-surface area) to bardoxolone methyl, at a daily dose of 20 mg, or placebo. The primary composite outcome was end-stage renal disease (ESRD) or death from cardiovascular causes. RESULTS: The sponsor and the steering committee terminated the trial on the recommendation of the independent data and safety monitoring committee; the median follow-up was 9 months. A total of 69 of 1088 patients (6%) randomly assigned to bardoxolone methyl and 69 of 1097 (6%) randomly assigned to placebo had a primary composite outcome (hazard ratio in the bardoxolone methyl group vs. the placebo group, 0.98; 95% confidence interval [CI], 0.70 to 1.37; P=0.92). In the bardoxolone methyl group, ESRD developed in 43 patients, and 27 patients died from cardiovascular causes; in the placebo group, ESRD developed in 51 patients, and 19 patients died from cardiovascular causes. A total of 96 patients in the bardoxolone methyl group were hospitalized for heart failure or died from heart failure, as compared with 55 in the placebo group (hazard ratio, 1.83; 95% CI, 1.32 to 2.55; P<0.001). Estimated GFR, blood pressure, and the urinary albumin-to-creatinine ratio increased significantly and body weight decreased significantly in the bardoxolone methyl group, as compared with the placebo group. CONCLUSIONS: Among patients with type 2 diabetes mellitus and stage 4 chronic kidney disease, bardoxolone methyl did not reduce the risk of ESRD or death from cardiovascular causes. A higher rate of cardiovascular events with bardoxolone methyl than with placebo prompted termination of the trial. (Funded by Reata Pharmaceuticals; BEACON ClinicalTrials.gov number, NCT01351675.).

Urine Albumin-Creatinine Ratio Versus Albumin Excretion for Albuminuria Staging: A Prospective Longitudinal Cohort Study.

BACKGROUND: New guidelines advocate the use of albumin-creatinine ratio (ACR) in a urine sample instead of 24-hour urinary albumin excretion (UAE) for staging albuminuria. Concern has been expressed that this may result in misclassification for reasons including interindividual differences in urinary creatinine excretion. STUDY DESIGN: Prospective longitudinal cohort study. SETTING & PARTICIPANTS: We examined 7,623 participants of the PREVEND and RENAAL studies for reclassified when using ACR instead of 24-hour UAE, the characteristics of reclassified participants, and their outcomes. Albuminuria was categorized into 3 ACR and UAE categories: <30, 30 to 300, and >300mg/g or mg/24 h, respectively. PREDICTORS: Baseline ACR and 24-hour UAE. OUTCOMES: Cardiovascular (CV) morbidity and mortality and all-cause mortality. RESULTS: When using ACR in the early morning void instead of 24-hour UAE, 88% of participants were classified in corresponding albuminuria categories. 307 (4.0%) participants were reclassified to a higher, and 603 (7.9%), to a lower category. Participants who were reclassified to a higher ACR category in general had a worse CV risk profile compared with nonreclassified participants, whereas the reverse was true for participants reclassified to a lower ACR category. Similarly, Cox proportional hazards regression analyses showed that reclassification to a higher ACR category was associated with a tendency for increased risk for CV morbidity and mortality and all-cause mortality, whereas reclassification to a lower ACR category was associated with a tendency for lower risk. Net reclassification improvement, adjusted for age, sex, and duration of follow-up, was 0.107 (P=0.002) for CV events and 0.089 (P<0.001) for all-cause mortality. LIMITATIONS: Early morning void urine collection instead of spot urine collection. CONCLUSIONS: Our results indicate that there is high agreement between early morning void ACR and 24-hour UAE categories. Reclassification is therefore limited, but when present, is generally indicative of the presence of CV risk factors and prognosis.

High urinary sulfate concentration is associated with reduced risk of renal disease progression in type 2 diabetes.

Diabetes is associated with a high incidence of microvascular disease, including nephropathy. Diabetic nephropathy is the most common cause of chronic kidney disease in the Western world. Sulfate in the urine is the metabolic end product of hydrogen sulfide (H2S), a recent discovered gaseous signaling molecule. Urinary sulfate has earlier shown beneficial predictive properties in renal transplant recipients. Based on the protective role of exogenous H2S in experimental models of diabetic nephropathy, we aimed to cross-sectionally investigate the association of sulfate with renal risk markers, and to prospectively investigate its predictive value for renal events in patients with diabetic nephropathy. Post-hoc analysis on data of the sulodexide macroalbuminuria (Sun-MACRO) trial and the Prevention of Renal and Vascular End-Stage Disease (PREVEND) study was performed. A total of 1004 patients with type 2 diabetes were included. Urinary sulfate concentration was measured and cross-sectionally associated to renal risk markers by linear regression. Multivariable Cox regression analysis was performed to assess the prospective association of sulfate with renal events, which was defined as end stage renal disease or a doubling of baseline serum creatinine. Mean age was 63 ± 9 years, median sulfate concentration was 8.0 (IQR 5.8-11.4) mmol/L. Urinary sulfate positively associated with male gender, hemoglobin, and negatively associated with albuminuria at baseline. During follow-up for 12 (IQR 6-18) months, 38 renal events occurred. Each doubling of urinary sulfate was associated with a 19% (95%CI 1%-34%) lower risk of renal events, independent of adjustment for potential confounders, including age, estimated glomerular filtration rate (eGFR), and albuminuria. To conclude, higher urinary sulfate concentration is associated with a more beneficial profile of renal risk markers, and is independently associated with a reduced risk for renal events in type 2 diabetes patients with nephropathy.

Vitamin D receptor activator and dietary sodium restriction to reduce residual urinary albumin excretion in chronic kidney disease (ViRTUE study): rationale and study protocol.

UNLABELLED: Optimal albuminuria reduction is considered essential to halting chronic kidney disease (CKD) progression. Both vitamin D receptor activator (VDRA) treatment and dietary sodium restriction potentiate the efficacy of renin-angiotensin-aldosterone-system (RAAS) blockade to reduce albuminuria. The ViRTUE study addresses whether a VDRA in combination with dietary sodium restriction provides further albuminuria reduction in non-diabetic CKD patients on top of RAAS blockade. The ViRTUE study is an investigator-initiated, prospective, multi-centre, randomized, double-blind (paricalcitol versus placebo), placebo-controlled trial targeting stage 1-3 CKD patients with residual albuminuria of >300 mg/day due to non-diabetic glomerular disease, despite angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use. During run-in, all subjects switched to standardized RAAS blockade (ramipril 10 mg/day) and blood pressure titrated to <140/90 mmHg according to a standardized protocol. Eligible patients are subsequently enrolled and undergo four consecutive study periods in random order of 8 weeks each: (i) paricalcitol (2 µg/day) combined with a liberal sodium diet (∼200 mmol Na(+)/day, i.e. mean sodium intake in the general population), (ii) paricalcitol (2 µg/day) combined with dietary sodium restriction (target: 50 mmol Na(+)/day), (iii) placebo combined with a liberal sodium diet and (iv) placebo combined with dietary sodium restriction. Data are collected at the end of each study period. The primary outcome is 24-h urinary albumin excretion. Secondary study outcomes are blood pressure, renal function (estimated glomerular filtration rate), plasma renin activity and, in a sub-population (N = 9), renal haemodynamics (measured glomerular filtration rate and effective renal plasma flow). A sample size of 50 patients provides 90% power to detect a 23% reduction in albuminuria, assuming a 25% dropout rate. Further reduction of residual albuminuria by combination of VDRA treatment and sodium restriction during single-agent RAAS-blockade will justify long-term studies on cardiorenal outcomes and safety. CLINICAL TRIAL REGISTRATION: NTR2898 (Dutch trial register).

Assessing the Validity of Surrogate Outcomes for ESRD: A Meta-Analysis.

Validation of current and promising surrogate outcomes for ESRD in randomized controlled trials (RCTs) has been limited. We conducted a systematic review and meta-analysis of RCTs to further inform the ability of surrogate outcomes for ESRD to predict the efficacy of various interventions on ESRD. MEDLINE, EMBASE, and CENTRAL (from inception through September 2013) were searched. All RCTs in adults with proteinuria, diabetes, or CKD stages 1-4 or renal transplant recipients reporting ≥10 ESRD events and a surrogate outcome (change in proteinuria or doubling of serum creatinine [DSCR]) for ESRD during a ≥1-year follow-up were included. Two reviewers abstracted trial characteristics and outcome data independently. To assess the correlation between the surrogate outcomes and ESRD, we determined the treatment effect ratio (TER), defined as the ratio of the treatment effects on ESRD and the effects on the change in surrogate outcomes. TERs close to 1 indicate greater agreement between ESRD and the surrogate, and these ratios were pooled across interventions. We identified 27 trials (97,458 participants; 4187 participants with ESRD). Seven trials reported the effects on change in proteinuria and showed consistent effects for proteinuria and ESRD (TER, 0.82; 95% confidence interval, 0.59 to 1.16), with minimal heterogeneity. Twenty trials reported on DSCR. Treatment effects on DSCR were consistent with the effects on ESRD (TER, 0.98; 95% confidence interval, 0.85 to 1.14), with moderate heterogeneity. In conclusion, DSCR is generally a good surrogate for ESRD, whereas data on proteinuria were limited. Further assessment of the surrogacy of proteinuria using prospective RCTs is warranted.

Sodium excretion and risk of developing coronary heart disease.

BACKGROUND: Despite compelling evidence for sodium's adverse effects on blood pressure, it remains uncertain whether excess sodium intake is a risk factor for coronary heart disease (CHD) in the overall population and in potentially more susceptible subgroups. METHODS AND RESULTS: We prospectively followed 7543 adults aged 28 to 75 years and free of cardiovascular and kidney disease in 1997/1998 of the Prevention of Renal and Vascular End-stage Disease (PREVEND) study. Sodium excretion was measured in two 24-hour urine collections at baseline. Potential susceptibility factors were blood pressure and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP). Median 24-hour sodium excretion was 137 mmol (Q1-Q3, 106-171 mmol). During a median follow-up of 10.5 (Q1-Q3: 9.9-10.8) years, 452 CHD events occurred. In the entire cohort, there was no association between each 1-g/d (43 mmol/24 h) increment in sodium excretion and CHD risk (adjusted hazard ratio, 1.07; 95% confidence interval, 0.98-1.18; P=0.15). However, the association of sodium excretion with CHD risk tended to be modified by mean arterial pressure (Pinteraction=0.08) and was modified by NT-proBNP (Pinteraction=0.002). When stratified, each 1-g/d increment in sodium excretion was associated with an increased risk for CHD in subjects with hypertension (adjusted hazard ratio, 1.14; 95% confidence interval, 1.01-1.28; n=2363) and in subjects with NT-proBNP concentrations above the sex-specific median (adjusted hazard ratio, 1.16; 95% confidence interval, 1.03-1.30; n=3771). CONCLUSIONS: Overall, there was no association between sodium excretion and risk of CHD. The association between sodium excretion and CHD risk was modified by NT-proBNP. Higher sodium excretion was associated with an increased CHD risk among subjects with increased NT-proBNP concentrations or with hypertension.