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Concept: Renal failure

396

Background Intravenous sodium bicarbonate and oral acetylcysteine are widely used to prevent acute kidney injury and associated adverse outcomes after angiography without definitive evidence of their efficacy. Methods Using a 2-by-2 factorial design, we randomly assigned 5177 patients at high risk for renal complications who were scheduled for angiography to receive intravenous 1.26% sodium bicarbonate or intravenous 0.9% sodium chloride and 5 days of oral acetylcysteine or oral placebo; of these patients, 4993 were included in the modified intention-to-treat analysis. The primary end point was a composite of death, the need for dialysis, or a persistent increase of at least 50% from baseline in the serum creatinine level at 90 days. Contrast-associated acute kidney injury was a secondary end point. Results The sponsor stopped the trial after a prespecified interim analysis. There was no interaction between sodium bicarbonate and acetylcysteine with respect to the primary end point (P=0.33). The primary end point occurred in 110 of 2511 patients (4.4%) in the sodium bicarbonate group as compared with 116 of 2482 (4.7%) in the sodium chloride group (odds ratio, 0.93; 95% confidence interval [CI], 0.72 to 1.22; P=0.62) and in 114 of 2495 patients (4.6%) in the acetylcysteine group as compared with 112 of 2498 (4.5%) in the placebo group (odds ratio, 1.02; 95% CI, 0.78 to 1.33; P=0.88). There were no significant between-group differences in the rates of contrast-associated acute kidney injury. Conclusions Among patients at high risk for renal complications who were undergoing angiography, there was no benefit of intravenous sodium bicarbonate over intravenous sodium chloride or of oral acetylcysteine over placebo for the prevention of death, need for dialysis, or persistent decline in kidney function at 90 days or for the prevention of contrast-associated acute kidney injury. (Funded by the U.S. Department of Veterans Affairs Office of Research and Development and the National Health and Medical Research Council of Australia; PRESERVE ClinicalTrials.gov number, NCT01467466 .).

Concepts: Sodium chloride, Placebo, Kidney, 25th century, 3rd millennium, Nephrology, Renal physiology, Renal failure

368

Background Canagliflozin is a sodium-glucose cotransporter 2 inhibitor that reduces glycemia as well as blood pressure, body weight, and albuminuria in people with diabetes. We report the effects of treatment with canagliflozin on cardiovascular, renal, and safety outcomes. Methods The CANVAS Program integrated data from two trials involving a total of 10,142 participants with type 2 diabetes and high cardiovascular risk. Participants in each trial were randomly assigned to receive canagliflozin or placebo and were followed for a mean of 188.2 weeks. The primary outcome was a composite of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke. Results The mean age of the participants was 63.3 years, 35.8% were women, the mean duration of diabetes was 13.5 years, and 65.6% had a history of cardiovascular disease. The rate of the primary outcome was lower with canagliflozin than with placebo (occurring in 26.9 vs. 31.5 participants per 1000 patient-years; hazard ratio, 0.86; 95% confidence interval [CI], 0.75 to 0.97; P<0.001 for noninferiority; P=0.02 for superiority). Although on the basis of the prespecified hypothesis testing sequence the renal outcomes are not viewed as statistically significant, the results showed a possible benefit of canagliflozin with respect to the progression of albuminuria (hazard ratio, 0.73; 95% CI, 0.67 to 0.79) and the composite outcome of a sustained 40% reduction in the estimated glomerular filtration rate, the need for renal-replacement therapy, or death from renal causes (hazard ratio, 0.60; 95% CI, 0.47 to 0.77). Adverse reactions were consistent with the previously reported risks associated with canagliflozin except for an increased risk of amputation (6.3 vs. 3.4 participants per 1000 patient-years; hazard ratio, 1.97; 95% CI, 1.41 to 2.75); amputations were primarily at the level of the toe or metatarsal. Conclusions In two trials involving patients with type 2 diabetes and an elevated risk of cardiovascular disease, patients treated with canagliflozin had a lower risk of cardiovascular events than those who received placebo but a greater risk of amputation, primarily at the level of the toe or metatarsal. (Funded by Janssen Research and Development; CANVAS and CANVAS-R ClinicalTrials.gov numbers, NCT01032629 and NCT01989754 , respectively.).

Concepts: Cardiovascular diseases, Low-density lipoprotein, Hypertension, Renal failure, Statistics, Cardiovascular disease, Atherosclerosis, Myocardial infarction

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BACKGROUND: The aim of this study was to determine the effects of creatine supplementation on kidney function in resistance-trained individuals ingesting a high-protein diet. METHODS: A randomized, double-blind, placebo-controlled trial was performed. The participants were randomly allocated to receive either creatine (20 g/d for 5 d followed by 5 g/d throughout the trial) or placebo for 12 weeks. All of the participants were engaged in resistance training and consumed a high-protein diet (i.e., >= 1.2 g/Kg/d). Subjects were assessed at baseline (Pre) and after 12 weeks (Post). Glomerular filtration rate was measured by 51Cr-EDTA clearance. Additionally, blood samples and a 24-h urine collection were obtained for other kidney function assessments. RESULTS: No significant differences were observed for 51Cr-EDTA clearance throughout the trial (Creatine: Pre 101.42 +/- 13.11, Post 108.78 +/- 14.41 mL/min/1.73m2; Placebo: Pre 103.29 +/- 17.64, Post 106.68 +/- 16.05 mL/min/1.73m2; group x time interaction: F = 0.21, p = 0.64). Creatinine clearance, serum and urinary urea, electrolytes, proteinuria, and albuminuria remained virtually unchanged. CONCLUSIONS: A 12-week creatine supplementation protocol did not affect kidney function in resistance-trained healthy individuals consuming a high-protein diet; thus reinforcing the safety of this dietary supplement.Trial registration: ClinicalTrials.gov NCT01817673.

Concepts: Kidney, Renal failure, Blood urea nitrogen, Renal function, Renal physiology, Urea, Electrolyte, Nephrology

207

Background The epidemiologic characteristics of children and young adults with acute kidney injury have been described in single-center and retrospective studies. We conducted a multinational, prospective study involving patients admitted to pediatric intensive care units to define the incremental risk of death and complications associated with severe acute kidney injury. Methods We used the Kidney Disease: Improving Global Outcomes criteria to define acute kidney injury. Severe acute kidney injury was defined as stage 2 or 3 acute kidney injury (plasma creatinine level ≥2 times the baseline level or urine output <0.5 ml per kilogram of body weight per hour for ≥12 hours) and was assessed for the first 7 days of intensive care. All patients 3 months to 25 years of age who were admitted to 1 of 32 participating units were screened during 3 consecutive months. The primary outcome was 28-day mortality. Results A total of 4683 patients were evaluated; acute kidney injury developed in 1261 patients (26.9%; 95% confidence interval [CI], 25.6 to 28.2), and severe acute kidney injury developed in 543 patients (11.6%; 95% CI, 10.7 to 12.5). Severe acute kidney injury conferred an increased risk of death by day 28 after adjustment for 16 covariates (adjusted odds ratio, 1.77; 95% CI, 1.17 to 2.68); death occurred in 60 of the 543 patients (11.0%) with severe acute kidney injury versus 105 of the 4140 patients (2.5%) without severe acute kidney injury (P<0.001). Severe acute kidney injury was associated with increased use of mechanical ventilation and renal-replacement therapy. A stepwise increase in 28-day mortality was associated with worsening severity of acute kidney injury (P<0.001 by log-rank test). Assessment of acute kidney injury according to the plasma creatinine level alone failed to identify acute kidney injury in 67.2% of the patients with low urine output. Conclusions Acute kidney injury is common and is associated with poor outcomes, including increased mortality, among critically ill children and young adults. (Funded by the Pediatric Nephrology Center of Excellence at Cincinnati Children's Hospital Medical Center and others; AWARE ClinicalTrials.gov number, NCT01987921 .).

Concepts: Ureter, Renal physiology, Renal failure, Odds ratio, Urine, Nephrology, Kidney, Epidemiology

172

The kidney functions in key physiological processes to filter blood and regulate blood pressure via key molecular transporters and ion channels. Sex-specific differences have been observed in renal disease incidence and progression, as well as acute kidney injury in response to certain drugs. Although advances have been made in characterizing the molecular components involved in various kidney functions, the molecular mechanisms responsible for sex differences are not well understood. We hypothesized that the basal expression levels of genes involved in various kidney functions throughout the life cycle will influence sex-specific susceptibilities to adverse renal events.

Concepts: Genetics, DNA, Renal failure, Blood pressure, Gene expression, Renin, Gene, Kidney

171

BACKGROUND: Fabry disease is an X-linked lysosomal storage disorder caused by alpha-galactosidase A deficiency leading to renal, cardiac, cerebrovascular disease and premature death. Treatment with alpha-galactosidase A (enzyme replacement therapy, ERT) stabilises disease in some patients, but long term effectiveness is unclear. METHODS: Renal, cardiac, and cerebral outcomes were prospectively studied in males and females with Fabry disease treated with ERT. Additionally, the occurrence of major cardiac events, stroke, end-stage renal disease and death was compared to a natural history (NH) cohort meeting treatment criteria. RESULTS: Of 75 patients on ERT (median treatment duration 5.2 years, range 0.05-11.0), prospective follow-up was available for 57 adult patients (30 males) and 6 adolescents. Renal function declined in males (-3.4 ml/min/1.73 m2 per year, SE 0.2; p < 0.001) despite ERT, but followed the normal course in females (-0.8 ml/min/1.73 m2 per year, SE 0.3; p = 0.001). Cardiac mass increased during ERT in males (+ 1.2 gram/m2.7, SE 0.3; p < 0.001), but remained stable in females (-0.3 gram/m2.7 per year, SE 0.4; p = 0.52). ERT did not prevent the occurrence of cerebral white matter lesions. Comparison of ERT treated to untreated patients revealed that the odds to develop a first complication increased with age (OR 1.05 (95% CI: 1.0-1.1) per year, p = 0.012). For development of a first or second complication the odds declined with longer treatment duration (OR 0.81 (95% CI: 0.68-0.96) per year of ERT, p = 0.015;OR 0.52 (0.31-0.88), p = 0.014 respectively). CONCLUSIONS: Long term ERT does not prevent disease progression, but the risk of developing a first or second complication declines with increasing treatment duration. ERT in advanced Fabry disease seems of doubtful benefit.

Concepts: Death, Chronic kidney disease, Kidney, Nephrology, Enzyme replacement therapy, Renal failure, Fabry disease, Lysosomal storage disease

171

The aim of this study was to evaluate the effect of Gd-chelate on renal function, iron parameters and oxidative stress in rats with CRF and a possible protective effect of the antioxidant N-Acetylcysteine (NAC). Male Wistar rats were submitted to 5/6 nephrectomy (Nx) to induced CRF. An ionic-cyclic Gd (Gadoterate Meglumine) was administrated (1.5 mM/KgBW, intravenously) 21 days after Nx. Clearance studies were performed in 4 groups of anesthetized animals 48 hours following Gd- chelate administration: 1–Nx (n = 7); 2–Nx+NAC (n = 6); 3–Nx+Gd (n = 7); 4–Nx+NAC+Gd (4.8 g/L in drinking water), initiated 2 days before Gd-chelate administration and maintained during 4 days (n = 6). This group was compared with a control. We measured glomerular filtration rate, GFR (inulin clearance, ml/min/kg BW), proteinuria (mg/24 hs), serum iron (µg/dL); serum ferritin (ng/mL); transferrin saturation (%), TIBC (µg/dL) and TBARS (nmles/ml). Normal rats treated with the same dose of Gd-chelate presented similar GFR and proteinuria when compared with normal controls, indicating that at this dose Gd-chelate is not nephrotoxic to normal rats. Gd-chelate administration to Nx-rats results in a decrease of GFR and increased proteinuria associated with a decrease in TIBC, elevation of ferritin serum levels, transferrin oversaturation and plasmatic TBARS compared with Nx-rats. The prophylactic treatment with NAC reversed the decrease in GFR and the increase in proteinuria and all alterations in iron parameters and TBARS induced by Gd-chelate. NAC administration to Nx rat did not modify the inulin clearance and iron kinetics, indicating that the ameliorating effect of NAC was specific to Gd-chelate. These results suggest that NAC can prevent Gd-chelate nephrotoxicity in patients with chronic renal failure.

Concepts: Transferrin, Transferrin saturation, Serum iron, Kidney, Dialysis, Renal function, Renal failure, Nephrology

171

Patients with end stage renal disease often fail to follow prescribed dietary and fluid regimen, leading to undesirable outcomes. This study aimed to examine and identify factors influencing dietary, fluid, medication and dialysis compliance behaviours in patients undergoing hemodialysis.

Concepts: Hemodialysis, Kidney, Peritoneum, Erythropoietin, Artificial kidney, Nephrology, Renal failure, Chronic kidney disease

170

Acute kidney injury (AKI) is a common consequence of systemic illness or injury and it complicates several forms of major surgery. Two major difficulties have hampered progress in AKI research and clinical management. AKI is difficult to detect early and its pathogenesis is still poorly understood. We recently reported results from multi-center studies where two urinary markers of cell-cycle arrest, tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) were validated for development of AKI well ahead of clinical manifestations-azotemia and oliguria. Cell-cycle arrest is known to be involved in the pathogenesis of AKI and this ‘dark side’ may also involve progression to chronic kidney disease. However, cell-cycle arrest has a ‘light side’ as well, since this mechanism can protect cells from the disastrous consequences of entering cell division with damaged DNA or insufficient bioenergetic resources during injury or stress. Whether we can use the light side to help prevent AKI remains to be seen, but there is already evidence that cell-cycle arrest biomarkers are indicators of both sides of this complex physiology.

Concepts: Nephrology, Cell division, Cell, Kidney, Chronic kidney disease, Renal failure, DNA, Cell nucleus

169

To assess the risk of medication errors in subjects with renal impairment (defined as an estimated glomerular filtration rate (eGFR) ≤40 ml/min/1.73 m(2)) and the effectiveness of automatic eGFR ≤40-alerts relayed to community pharmacists.

Concepts: Glomerulus, Kidney, Dialysis, Renal function, Nephrology, Renal failure