Clark WF, et al. - Authors investigated the effect of coaching to increase water intake on kidney function in adults with chronic kidney disease in 9 centers in Ontario, Canada, from 2013 until 2017. Findings demonstrated that among adults with chronic kidney disease, coaching to increase water intake compared with coaching to maintain the same water intake did not notably slow the decline in kidney function after 1 year.

Methods

• Researchers performed the CKD WIT (Chronic Kidney Disease Water Intake Trial) randomized clinical trial in 9 centers in Ontario, Canada, from 2013 until 2017 (last day of follow-up, May 25, 2017).
• Subjects presented with stage 3 chronic kidney disease (estimated glomerular filtration rate [eGFR] 30-60 mL/min/1.73 m² and microalbuminuria or macroalbuminuria) and a 24-hour urine volume of less than 3.0 L.
• During this study, enrollees in the hydration group (n = 316) were coached to drink more water, and those in the control group (n = 315) were coached to maintain usual intake.
• Change in kidney function (eGFR from baseline to 12 months) served as the primary outcome.
• Secondary outcomes constituted 1-year change in plasma copeptin concentration, creatinine clearance, 24-hour urine albumin, and patient-reported overall quality of health (0 [worst possible] to 10 [best possible]).

Results

• Among 631 randomized patients (mean age, 65.0 years; men, 63.4%; mean eGFR, 43 mL/min/1.73 m²; median urine albumin, 123 mg/d), 12 died (hydration group [n = 5]; control group [n = 7]).
• It was reported that out of 590 survivors with 1-year follow-up measurements (95% of 619), the mean change in 24-hour urine volume was 0.6 L per day higher in the hydration group (95% CI, 0.5 to 0.7; P < .001).
• Findings displayed that the mean change in eGFR was -2.2 mL/min/1.73 m² in the hydration group and -1.9 mL/min/1.73 m² in the control group (adjusted between-group difference, -0.3 mL/min/1.73 m² [95% CI, -1.8 to 1.2; P=.74]).
• Results depicted the mean between-group differences (hydration vs control) in secondary outcomes as follows: plasma copeptin, -2.2 pmol/L (95% CI, -3.9 to -0.5; P=.01); creatinine clearance, 3.6 mL/min/1.73 m² (95% CI, 0.8 to 6.4; P=.01); urine albumin, 7 mg per day (95% CI, -4 to 51; P=.11); and quality of health, 0.2 points (95% CI, -0.3 to 0.3; P=.22).