Fluid status, malnutrition and physical function relationship in chronic kidney disease: A cross-sectional observational pooled analysis study.

OBJECTIVE: Water load fluctuations may drive hyper-catabolism and inflammation, contributing to nutritional and functional impairment. This hypothesis-generating study investigated the relationship of volemia with malnutrition and physical function among patients with chronic kidney disease (CKD). DESIGN AND METHODS: Assessment and diagnoses were performed at mid-week, after hemodialysis or removal of peritoneal fluid. Volemia was assessed by bioelectrical impedance vector analysis (BIVA) and applied to stratify total sample in hypovolemic (HV-) and euvolemic-hypervolemic (EV-HV+) groups. Muscle and adiposity-related measurements were assessed. Hand-grip strength (HGS) evaluated muscle strength. Low muscle strength, malnutrition, sarcopenia and sarcopenic obesity were diagnosed. Regression analysis verified association between variables. Hotelling's T2 test assessed impedance vectors differences. RESULTS: Of 362 individuals, 254 were HV- and 108 were EV-HV+. HV- group presented lower muscle and fat (P < 0.05). Differences in malnutrition, sarcopenia and sarcopenic obesity prevalence between groups were dependent on definition for muscle mass impairment: applying low calf circumference, HV- individuals presented 2.53, 2.58 and 3.27 higher risk for malnutrition, sarcopenia and sarcopenic obesity (P < 0.05), respectively. Low HGS was present in 41% and 27% of HV- and EV-HV+ groups (P = 0.000). HV- status lowered HGS by 2kgs (ꞵ = -2.01; P = 0.059), with a 1.75 odds ratio for low muscle strength (P = 0.070) as compared to EV-HV+ status. BIVA revealed significant differences in the confidence ellipses for presence and absence of conditions diagnosed. CONCLUSIONS: In CKD, hypovolemia presented a non-significant trend toward lower muscle strength, warranting confirmation in future studies. Associations of volemia with malnutrition, sarcopenia and sarcopenic obesity were dependent on muscle mass parameter applied.