Water intake, baseline biopsy, and graft function after living donor kidney transplantation

Abstract

Increased water intake is recommended for kidney transplant recipients; however, its efficacy remains controversial. We hypothesized that pre-existing histological findings of the allograft might modulate the impact of water intake. We retrospectively analyzed 167 adults with living-donor kidney transplants (April 2011-May 2020; median observation period, 77 months) whose baseline biopsy data were available. We compared the chronic-change group (n = 38) with the control group (n = 129) to assess the impact of self-reported daily water intake on the estimated glomerular filtration rate (eGFR). The range distribution of water intake was as follows: - 1000 ml (n = 4), 1000-1500 ml (n = 23), 1500-2000 ml (n = 64), 2000-2500 ml (n = 57), 2500-3000 ml (n = 16), and 3000 - ml (n = 3). Donor age was significantly higher in the chronic-change group. In the control group, the ΔeGFR/year increase was correlated with water intake. However, the increase in the water intake of the chronic-change group significantly decreased ΔeGFR/year (1000-1500 ml: + 1.95 ml/min/1.73 m² and > 2000 ml: - 1.92 ml/min/1.73 m², p = 0.014). This study suggested a potential influence of increased water intake on recipients with marginal grafts in living donor kidney transplantation.

Keywords: Biopsy; Graft function; Kidney transplantation; Water intake.

Figure 1

The relationship between the ΔeGFR/year and the amount of daily water intake. (A) Overall, (B) control vs. chronic change group, (C) 1-year UP < 1 vs. 1-year UP ≥ 1, and (D) 1-year eGFR < 45 vs. 1-year eGFR ≥ 45. ^※p < 0.05. eGFR estimated glomerular filtration rate, ΔeGFR/year eGFR slope, UP urine protein.

Figure 2

Interaction analyses for the impact of daily water intake on the ΔeGFR/year. The odds ratio for ΔeGFR/year < − 1 or not. Adjusted for recipient gender and age. P values for interactions. aOR adjusted odds ratio, CI confidence interval, eGFR estimated glomerular filtration rate, ΔeGFR/year eGFR slope.

Figure 3

Graft survivals after living donor kidney transplantation. (A) Control vs. chronic change group, (B) 1-year UP < 1 vs. 1-year UP ≥ 1, (C) 1-year eGFR ≥ 45 vs. 1-year eGFR < 45, and (D) water intake category. eGFR estimated glomerular filtration rate, UP urine protein.