Comparison of energy estimates in chronic kidney disease using doubly-labelled water.

BACKGROUND Total energy expenditure (TEE) is estimated in clinical practice as a combined measure of resting energy expenditure and physical activity level. Commonly available questionnaires to estimate physical activity level have not been validated in patients with kidney disease using the doubly-labelled water method. METHODS This prospective, cross-sectional study was conducted on 40 patients with chronic kidney disease stages 1-5 with the objective of validating two physical activity questionnaires: the Recent Physical Activity Questionnaire (RPAQ) and the Stanford 7-day recall questionnaire. TEE was measured using doubly-labelled water technique. TEE was also estimated using predicted resting energy expenditure and estimated physical activity measures from the questionnaires. RESULTS Measured TEE correlated better with TEE estimated from RPAQ compared to that from the Stanford questionnaire. In Bland-Altman analysis, TEE estimated from RPAQ had the least bias and narrower limits of agreement compared to the measured TEE. A metabolic equivalent of task value of 1.3 for the unaccounted time in RPAQ provided the best approximation of estimated TEE to the measured TEE. CONCLUSIONS RPAQ is an acceptable questionnaire tool for assessing physical activity level in patients with chronic kidney disease.