Longitudinal study of nutritional status, body composition, and physical function in hemodialysis patients.

BACKGROUND: Cross-sectional studies have shown an association between the duration (y) of dialysis and nutritional status, providing evidence of wasting.
OBJECTIVE: The aim was to determine the extent, pace, determinants, and optimal methods of assessing wasting in patients undergoing hemodialysis.
DESIGN: Laboratory variables, body composition, and physical activity, function, and performance were tested 4 times over 1 y in 54 hemodialysis patients. Changes in repeated measures were evaluated, with adjustment for baseline differences by age, sex, race, diabetes status, and dialysis vintage (ie, time since initiation of dialysis).
RESULTS: No significant changes in body weight, fat mass, lean body mass, or laboratory variables were observed. Phase angle, a bioelectrical impedance analysis-derived variable related to body cell mass, decreased significantly (linear estimate: -0.043 degrees /mo, or approximately 0.5 degrees/y; P = 0.001). Physical activity measured by accelerometry declined 3.4%/mo (P = 0.01). The Maximum Activity Score of the Human Activity Profile (HAP) also declined significantly (linear estimate: -0.50/mo, or approximately 6 points/y; P = 0.025). Higher interleukin 1beta (IL-1beta) concentrations were associated with a narrower phase angle (P = 0.004) and with a more rapid decline in phase angle with time (time x IL-1beta interaction, P = 0.01); similar effects of IL-1beta on physical activity were observed. Dietary protein and energy intakes were associated with changes in the HAP.
CONCLUSIONS: Evidence of adverse changes in body composition and physical activity, function, and performance and of a modest influence of inflammation and dietary intake on these changes was observed in this cohort. Tools such as bioelectrical impedance analysis, accelerometry, and the HAP may be required to identify subtle changes.