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 T 2 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.