Evaluation of air-displacement plethysmography for body composition assessment in preterm infants

Background:Adiposity may contribute to the future risk of disease. The aim was to evaluate the accuracy and reliability of an air-displacement plethysmography system (ADP) to estimate percentage fat mass (%FM) in preterm infants and to evaluate inter-device reliability in infants.Methods:70 preterm and 9 full term infants were assessed. The accuracy of ADP measurements was assessed by determining reference %FM values using H(2)(18)O dilution measurement.Results:Mean %FM by ADP was 5.67 ± 1.84 and mean % FM by H(2)(18)O dilution was 5.99 ± 2.56. Regression analysis showed that % FM by ADP was associated with %FM by H(2)(18)O dilution (R(2)=0.63,standard error of estimate (SEE)=1.65, P=0.006). Bland-Altman analysis showed no bias (r=-0.48, P=0.16) and 95% limits of agreement were -3.40 to 2.76 %FM. There was no difference in mean inter-device reliability %FM values (8.97 vs. 8.55 %FM) between ADP 1 and 2. Regression analysis indicated a low SEE (1.14% FM), high R(2) (0.91) and 95% limits of agreement were -1.87 to 2.71% FM. The regression line also did not differ significantly from the line of identity.Conclusion:ADP is a noninvasive, reliable, and accurate technique to measure preterm infants' body composition in both research and clinical settings.