Risk Factors for Decline of Residual Renal Function in Children Treated With Peritoneal Dialysis

♦ BACKGROUND: The aim of the study was to assess risk factors for residual renal function (RRF) decline in children during the first/second year of chronic peritoneal dialysis (PD). ♦ METHODS: The study group included 56 children with end-stage renal disease (ESRD) (age 10.13 ± 4.86 years), including 18 on continuous ambulatory PD (CAPD) and 38 on automated PD (APD), in whom we evaluated RRF (daily diuresis [mL/m²/24 h], residual glomerular filtration rate (rGFR) [mL/min/1.73 m²]), etiology of ESRD, PD fluid volume (mL/m²/24 h), glucose load (g/m²/24 h), ultrafiltration (mL/m²/24 h), peritoneal permeability (D/P_{Crea 4h}, D/D_{0 Glu 4h}), dialysis adequacy (twKt/V, twCCr [L/week/1.73 m²]), blood pressure (BP), biochemical parameters, and medications used. Duration of follow-up was 24 months. ♦ RESULTS: Mean diuresis before initiation of PD was 1,394.93 ± 698.37 (mL/m²/24 h), and mean rGFR was 7.41 ± 3.96 (mL/min/1.73 m²). The rate of daily diuresis decline was -529.34 ± 546.28 in the first year and -107.10 ± 291.54 (mL/m²/24 h) in the second year (p = 0.005), and the rate of rGFR decline was -3.35 ± 3.73 in the first year and -1.63 ± 1.85 (mL/min/1.73 m²) in the second year (p = 0.118). Eleven (19.64%) patients became anuric. In univariate analysis, the rate of daily diuresis decline in the first year was related to baseline diuresis (r = -0.29, p = 0.031), proteinuria (r = -0.43, p = 0.001), and systolic BP (r = -0.31, p = 0.020); 12-month changes (Δ0 - 12) in PD fluid volume (r = -0.37, p = 0.004), glucose load (r = -0.28, p = 0.035), and ultrafiltration (r = -0.38, p = 0.004); serum calcium-phosphorus product (r = -0.41, p = 0.002); and Δ0 - 12 body mass index (BMI) Z-score (r = 0.30, p = 0.024); while the rate of rGFR decline in the first year was related only to baseline rGFR (r = -0.57, p < 0.001). In multivariate analysis, significant predictors of the rate of daily diuresis decline in the first year were baseline diuresis (β = -0.386, p < 0.001) and proteinuria (β = -0.278, p = 0.017), mean systolic BP Z-score (β = -0.237, p = 0.027), and age at the onset of PD (β = -0.224, p = 0.037), while predictors of the rate of rGFR decline were baseline rGFR (β = -0.607, p < 0.001) and baseline proteinuria (β = -0.225, p = 0.046). In the second year, the only predictors of the rate of rGFR decline were D/D_{0 Glu 4h} (r = 0.44, p = 0.033, univariate analysis) and rGFR at 12 months (β = -0.499, p = 0.044). ♦ CONCLUSION: The most important risk factors for rapid RRF decline in children during the first year of chronic PD include higher baseline daily diuresis and proteinuria, and additional factors are systolic BP and age at the onset of PD; while high baseline GFR and low peritoneal transport status may be the only important factors during the second year.