Prevalence and risk factors of fluid overload in Southern Chinese continuous ambulatory peritoneal dialysis patients

Abstract

Background: Fluid overload is frequently present in CAPD patients and one of important predictors of mortality. The aim of this study is to investigate the prevalence and associated risk factors in a cohort study of Southern Chinese CAPD patients.

Methods: The patients (receiving CAPD 3 months and more) in our center were investigated from January 1, 2008 to December 31, 2009. Multi-frequency bioelectrical impedance analysis was used to assess the patient's body composition and fluid status.

Results: A total of 307 CAPD patients (43% male, mean age 47.8±15.3 years) were enrolled, with a median duration of PD 14.6 (5.9-30.9) months. Fluid overload (defined by Extracellular water/Total body water (ECW/TBW)≥0.40) was present in 205 (66.8%) patients. Univariate analysis indicated that ECW/TBW were inversely associated with body mass index (r = -0.11, P = 0.047), subjective global assessment score (r = -0.11, P = 0.004), body fat mass (r = -0.15, P = 0.05), serum albumin (r = -0.32, P<0.001), creatinine (r = -0.14, P = 0.02), potassium (r = -0.15, P = 0.02), and residual urine output (r = -0.14, P = 0.01), positively associated with age (r = 0.27, P<0.001), Chalrlson Comorbidity Index score (r = 0.29, P<0.001), and systolic blood pressure (r = 0.22, P<0.001). Multivariate linear regression showed that lower serum albumin (β = -0.223, P<0.001), lower body fat mass (β = -0.166, P = 0.033), old age (β = 0.268, P<0.001), higher systolic blood pressure (β = 0.16, P = 0.006), less residual urine output (β = -0.116, P = 0.042), and lower serum potassium (β = -0.126, P = 0.03) were independently associated with higher ECW/TBW. After 1 year of follow-up, the cardiac event rate was significantly higher in the patients with fluid overload (17.1% vs 6.9%, P = 0.023) than that of the normal hydrated patients.

Conclusions: The prevalence of fluid overload was high in CAPD patients. Fluid overload in CAPD patients were independently associated with protein-energy wasting, old age, and decreased residual urine output. Furthermore, CAPD patients with fluid overload had higher cardiac event rate than that of normal hydrated patents.

Figure 1. ROC analysis of edema for fluid overload (AUC = 0.653, sensitivity 0.562, specificity 0.745, P<0.001).

Figure 2. ECW/TBW in the CAPD patients with and without malnutrition.

*, P<0.05; SGA, subjective global assessment.

Figure 3. ECW/TBW in the CAPD patients with and without CVD.

**, P<0.01; CVD, cardiovascular disease.

Figure 4. ECW/TBW in the diabetic and non-diabetic CAPD patients.

**, P<0.01; DM: diabetes mellitus.

Figure 5. ECW/TBW was positively correlated with systolic blood pressure (mmHg).

Figure 6. ECW/TBW was negatively correlated with residual urine output (ml/24

h).