Granulomatosis with polyangiitis (GPA, Wegener’s) and microscopic polyangiitis (MPA) are small vessel vasculitides collectively referred to as anti-neutrophil cytoplasm antibody-associated vasculitis (AAV). AAV is associated with high rates of morbidity and mortality due to uncontrolled disease and treatment toxicity. Small randomized trials suggest adjunctive plasma exchange may improve disease control, while observational evidence suggests that current oral glucocorticoid doses are associated with severe infections in patients with AAV. A randomized study of both plasma exchange and glucocorticoids is required to evaluate plasma exchange and oral glucocorticoid dosing in patients with AAV.

Background: Evidence from animal and human studies suggests a protective effect of higher water intake on kidney function and cardiovascular disease (CVD). Here the associations between water intake, chronic kidney disease (CKD) and CVD were examined in the general population. Methods: We conducted a cross-sectional analysis of the 2005-2006 National Health and Nutrition Examination Survey. Non-pregnant adults with an estimated glomerular filtration rate (eGFR) ≥30 ml/min/1.73 m² who were not taking diuretics were included. Total water intake from foods and beverages was categorized as low (4.3 l/day). We examined associations between low total water intake and CKD (eGFR 30-60 ml/min/1.73 m²) and self-reported CVD. Results: Of 3,427 adults (mean age 46 (range 20-84); mean eGFR 95 ml/min/1.73 m² (range 30-161)), 13% had CKD and 18% had CVD. CKD was higher among those with the lowest (4.3 l/day) (adjusted odds ratio (OR) 2.52; 95% confidence interval (CI) 0.91-6.96). When stratified by intake of (1) plain water and (2) other beverages, CKD was associated with low intake of plain water: adjusted OR 2.36 (95% CI 1.10-5.06), but not other beverages: adjusted OR 0.87 (95% CI 0.30-2.50). There was no association between low water intake and CVD (adjusted OR 0.76; 95% CI 0.37-1.59). Conclusions: Our results provide additional evidence suggesting a potentially protective effect of higher total water intake, particularly plain water, on the kidney.

Summary: Background and objectives: The effect of increased fluid intake on kidney function is unclear. This study evaluates the relationship between urine volume and renal decline over 6 years in a large community-based cohort. Design, setting, participants, & measurements: This prospective cohort study was undertaken in Canada from 2002 to 2008. We obtained 24-hour urine samples from adult participants with an estimated GFR (eGFR) ≥60ml/min per 1.73 m² at study entry. Percentage annual change in eGFR from baseline was categorized as average decline <1% per year, between 1% and 4.9% (mild-to-moderate decline) or ≥5% (rapid decline). Results: 2148 participants provided valid 24-hour urine samples, grouped as <1 L/d (14.5%); 1 to 1.9 L/d (51.5%); 2 to 2.9 L/d (26.3%); and ≥3 L/d (7.7%). Baseline eGFR for each category of urine volume was 90, 88, 84, and 87 ml/min per 1.73 m², respectively. Overall, eGFR declined by 1% per year, with 10% demonstrating rapid decline and 40% demonstrating mild-to-moderate decline. An inverse, graded relationship was evident between urine volume and eGFR decline: For each increasing category of 24-hour urine volume, percentage annual eGFR decline was progressively slower, from 1.3%, 1.0%, 0.8%, to 0.5%, respectively; P = 0.02. Compared with those with urine volume 1 to 1.9 L/d, those with urine volume ≥3 L/d were significantly less likely to demonstrate mild-to-moderate decline (adjusted odds ratio 0.66; 95% confidence interval 0.46 to 0.94) or rapid decline (adjusted odds ratio 0.46; 95% confidence interval 0.23 to 0.92); adjusted for age, gender, baseline eGFR, medication use for hypertension (including diuretics), proteinuria, diabetes, and cardiovascular disease. Conclusions: In this community-based cohort, decline in kidney function was significantly slower in those with higher versus lower urine volume.

Background Recent studies have reported a trend toward earlier initiation of dialysis (i.e., at higher levels of glomerular filtration rate) and an association between early initiation and increased risk of death. We examined trends in initiation of hemodialysis within Canada and compared the risk of death between patients with early and late initiation of dialysis. Methods The analytic cohort consisted of 25 910 patients at least 18 years of age who initiated hemodialysis, as identified from the Canadian Organ Replacement Register (2001–2007). We defined the initiation of dialysis as early if the estimated glomerular filtration rate was greater than 10.5 mL/min per 1.73 m². We fitted time-dependent proportional-hazards Cox models to compare the risk of death between patients with early and late initiation of dialysis. Results Between 2001 and 2007, mean estimated glomerular filtration rate at initiation of dialysis increased from 9.3 (standard deviation [SD] 5.2) to 10.2 (SD 7.1) (p < 0.001), and the proportion of early starts rose from 28% (95% confidence interval [CI] 27%–30%) to 36% (95% CI 34%–37%). Mean glomerular filtration rate was 15.5 (SD 7.7) mL/min per 1.73 m² among those with early initiation and 7.1 (SD 2.0) mL/min per 1.73 m² among those with late initiation. The unadjusted hazard ratio (HR) for mortality with early relative to late initiation was 1.48 (95% CI 1.43–1.54). The HR decreased to 1.18 (95% CI 1.13–1.23) after adjustment for demographic characteristics, serum albumin, primary cause of end-stage renal disease, vascular access type, comorbidities, late referral and transplant status. The mortality differential between early and late initiation per 1000 patient-years narrowed after one year of follow-up, but never crossed and began widening again after 24 months of follow-up. The differences were significant at 6, 12, 30 and 36 months. Interpretation In Canada, dialysis is being initiated at increasingly higher levels of glomerular filtration rate. A higher glomerular filtration rate at initiation of dialysis is associated with an increased risk of death that is not fully explained by differences in baseline characteristics.

Quiz Ref ID Despite widespread interest, little scientific data exist on the optimal amount of water to drink. The popular advice to “drink at least 8 glasses of water a day” originated not from primary research, but from the US Food and Nutrition Board in 1945, which recommended a daily water intake of 2.5 L per day and stated that the majority of this intake could come from food sources.^1,2 While many claims about the benefits of increased water intake remain untested,^2-4 a growing body of evidence suggests that drinking more water may benefit the kidneys.^5,6 In animals that undergo a near complete bilateral nephrectomy, drinking more water suppresses the plasma concentration of vasopressin and improves creatinine clearance,^7,8 and in studies of humans, drinking more water is associated with better kidney function and a reduced risk of kidney stones.^9-13 Whether increased water intake can benefit patients with chronic kidney disease remains unknown.