Increased Water Consumption Does Not Enhance Kidney Function in Chronic Kidney Disease

Consuming more water does not affect the prevention of kidney function decline in patients with chronic kidney disease (CKD), according to a study published in JAMA.

William F. Clark, MD, of London Health Sciences Centre in Ontario, Canada, and associates conducted the Chronic Kidney Disease Water Intake Trial (CKD WIT) to assess the relationship between elevated water consumption and kidney function improvement.

The investigators invited 631 randomized participants with stage 3 CKD and 24-hour urine volumes less than 3 liters to partake in the CKD WIT study in 9 centers in Ontario from 2013 to 2017. Stage 3 CKD was defined with estimated glomerular filtration rates (eGFR) of 30 to 60 mL/min/1.73 m² and microalbuminuria or macroalbuminuria.

Volunteers were either trained to drink more water (n=316) or required to maintain their average water intake (n=315). Adjustment in kidney function was the primary outcome measured, while 1-year alterations in plasma copeptin concentrations, creatinine clearance, 24-hour urine albumin, and overall quality of health (patient-rated 0 [worst] to 10 [best]) were secondary outcomes measured.

Participants were mostly men (63.4%) with an average age of 65 years and an average eGFR of 43 mL/min/1.73m² (median urine albumin, 123 mg/d). During the duration of the study, 12 patients died: 5 members of the hydration group and 7 from the control group.

Of the remaining 590 individuals, the average change in 24-hour urine volume was increased by 0.6 liters a day in the case cohort. The average change in eGFR was -2.2 mL/min/1.73m² and -1.9 mL/min/1.73m² in the case and control groups, respectively.

Secondary outcomes measured as average intergroup differences were -2.2pmol/L for plasma copeptin concentrations, 3.6 mL/min/1.73m² for creatinine clearance, 7 mg/day for urine albumin, and 0.2 points for patient-reported quality of health.

“Among adults with chronic kidney disease, coaching to increase water intake compared with coaching to maintain the same water intake did not significantly slow the decline in kidney function after 1 year,” according to the researchers. “However, the study may have been underpowered to detect a clinically important difference.”

Clark WF, Sontrop JM, Huang S, et al. Effect of coaching to increase water intake on kidney function decline in adults with chronic kidney disease: The CKD WIT randomized clinical trial. JAMA. 2018;319(18):1870–1879.