The chronic kidney disease Water Intake Trial (WIT): results from the pilot randomised controlled trial

摘要

Background and objectives Increased water intake may benefit kidney function. Prior to initiating a larger randomised controlled trial (RCT), we examined the safety and feasibility of asking adults with chronic kidney disease (CKD) to increase their water intake. Design, setting, participants and measurements Beginning in October 2012, we randomly assigned 29 adults with stage 3 CKD (estimated glomerular filtration rate (eGFR) 30–60?mL/min/1.73?m2 and albuminuria) to one of the two groups of water intake: hydration (n=18) or standard (n=11). We asked the hydration group to increase their water intake by 1.0–1.5?L/day (in addition to usual intake, depending on sex and weight) for 6?weeks, while the control group carried on with their usual intake. Participants collected a 24?h urine sample at baseline and at 2 and 6?weeks after randomisation. Our primary outcome was the between-group difference in change in 24?h urine volume from baseline to 6?weeks. Results (63%)of participants were men, 81% were Caucasians and the average age was 61?years (SD 14 years). The average baseline eGFR was 40?mL/min/1.73?m2 (SD 11?mL/min/1.73?m2); the median albumin to creatinine ratio was 19?mg/mmol (IQR 6–74?mg/mmol). Between baseline and 6-week follow-up, the hydration group's average 24?h urine volume increased by 0.7?L/day (from 2.3 to 3.0?L/day) and the control group's 24?h urine decreased by 0.3?L/day (from 2.0 to 1.7?L/day; between-group difference in change: 0.9?L/day (95% CI 0.4 to 1.5; p=0.002)). We found no significant changes in urine, serum osmolality or electrolyte concentrations, or eGFR. No serious adverse events or changes in quality of life were reported. Conclusions A pilot RCT indicates adults with stage 3 CKD can successfully and safely increase water intake by up to 0.7?L/day in addition to usual fluid intake. Trial registration Registered with Clinical Trials—government identifier NCT01753466.