Introduction:
Coaching to Increase Water Intake (CIWI) can be both beneficial and harmful in Chronic Kidney Disease (CKD), depending on kidney function and Kidney Functional Reserve (KFR).
The aim of this study is to clarify the effectiveness of CIWI in healthy volunteers and CKD patients (stages G1-G5) based on follow-up results.
Methods:
We analyzed changes in glomerular filtration rate (eGFR), albumin/cretinine ratio (ACR), kidney functional reserve, quality of health (QH) and blood pressure (BP) in patients with CKD stages 1, 2, 4, and 5 under forced hydration after completion of previous studies, with an additional 1-year follow-up.
The "Early Coaching to Increase Water Intake in CKD (ECIWIC)" study involved patients with CKD stages 1-2, who were coached to increase their diuresis to 1.7-2 L without sodium chloride supplementation over 12 months. Primary endpoint: change in eGFR; secondary endpoints: (ACR) and QH on a scale from 0 (worst) to 10 (best).
The "HYD45 — Hydration in CKD Stages 4-5" study included 40 patients with CKD stages 4-5, evaluating eGFR with/without CIWI aiming for a diuresis increase of 400 mL. Measurements were taken at baseline, 6 months, and 12 months.
A comparison group consisted of patients from Clark WF et al.'s study1 assessing eGFR in CKD stage 3. This randomized clinical follow-up involved patients with CKD stage 3 over 12 months.
A control group of 123 healthy individuals was surveyed to assess their fluid intake and urine output. Additionally, 60 volunteers increased their water intake over a week to determine a comfortable additional fluid amount.
Results:
Annual observations indicated that CIWI preserved eGFR in CKD stages 1-2 but decreased it in stage 5. The data suggests healthy individuals should consume fluid amount ensuring physiological diuresis (1.2-1.8 L) and normo-osmolarity of urine. CIWI may often lead to excessive hydration, particularly as kidney function declines. The benefits of CIWI appears to diminish with CKD progression.
For CKD stages 1-2, CIWI may positively impact eGFR over 24 months (RR 0.857, 95% CI 0.692-1.062, NNT 7.0), whereas it may be impractical for stages 4-5 (RR 0.799, 95% CI 0.893-1.162, NNT 14.0). The ECIWIC trial demonstrated CIWI benefits in CKD stages 1-2 with preserved KFR, potentially delaying CKD progression.
Among 123 volunteers 46% were inadequately hydrated based on physiological urine volume (1200-1800 ml) or impedance percentage, indicating insufficient fluid intake.
Changes in eGFR in CKD 1-5 (mL/min/m2)
Conclusions:
Coaching to increase water intake has bouncebackability and positive effects on eGFR, ACR, quality of health over 24 months in CKD stages 1-2 with high kidney functional reserve or eGFR above 90 ml/min/m2. However, CIWI becomes excessive with declining renal function, and does not necessarily promote a healthy lifestyle in low KFR and CKD G4-5. CIWI is controversial in CKD G3, probably, depending on kidney functional reserve, and likely inadvisable and antithetical in CKD stages 4-5, especially stage 5, accompanied by increasing of blood pressure, and overall benefits of CIWI are likely lost in progressive CKD with annual decrease eGFR above 5-7 ml/min/m2.
Proper hydration recommendations involve fluid intake that ensures physiological diuresis (1.2–1.8 L) and normal urine osmolarity in healthy volunteers. About 46% of volunteer individuals may not drink enough to stay adequately hydrated. An additional 720 ml/day of fluid is comfortable, increasing urine output by 560 ml/day. More than 720 ml causes discomfort, while less than 720 ml does not significantly increase urine output.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.