Air-displacement plethysmography for the measurement of body composition in children aged 6–48 months

Abstract

IntroductIon: air-displacement plethysmography (aDP) is an age-appropriate method for measuring relative fat mass (%FM) in children; however, the accuracy of this method has not been evaluated in children aged 5 y or younger. results: Mean %FM values measured by aDP (17.9 ± 8.0%) and by total body water (TBW) (23.7 ± 6.3%) were significantly different (P < 0.001). Regression analysis of %FM by aDP vs. TBW provided a line of best fit with a slope of 0.089, r 2 = 0.013, and standard error of the estimate (see) = 6.3% FM (P = 0.40). dIscussIon: The error was related to child weight and %FM, but not to behaviors (movement or vocalizations) occurring during the test sequence. a large portion of the error was attributable to imprecision in measuring small volumes. as currently designed, aDP is not an accurate method for measuring %FM in young children. Further investigation of the sources of variability will provide insight into ways of improving the accuracy of this technology for this population. Methods: This study examined the accuracy of an aDP system modified for young children (BOD POD; Life Measurement, concord, ca) by comparing %FM results from aDP with those obtained from TBW by deuterium (D 2 O) dilution (reference method) in 72 children aged 6-48 mo.

Challenges in infant body composition

“…The four-compartment model is superior to any single method, given that it relies upon the fewest assumptions in the estimation of body composition (5,6). In conclusion, we believe the study by Rosendale and Bartok (2) has several methodological limitations, requiring further work to assess the validity of the BOD POD Pediatric Option in very young children. We suggest that behavioral issues in this age group are likely to prohibit its use in infants <2 y.…”

“…The Pediatric Option accommodates children who are too large for the infant ADP (PEA POD), but not mature enough to adhere to the commands/procedures of the BOD POD. The recent paper by Rosendale and Bartok (2) suggests that the Pediatric Option fails to fill the remaining gap between 6 mo and 2 y of age. However, there are a number of methodological concerns regarding the study that indicate additional work is needed to firmly conclude whether or not the Pediatric Option can provide valid estimates of body composition in this age range.…”

“…The authors reported “no association between behavior (crying and movement) and body composition”; however, in the study by Fields and Allison (1), comprehensive data on vocalization and movement were collected, and subject noncompliance (chiefly crying) in children <2 y was common (~40%), resulting in a 7.2% fat unit difference as compared with the four-compartment model. The study by Rosendale and Bartok (2) did not attempt to examine the validity of the Pediatric Option among the subset of children who were able to successfully complete three repeated measurements of body volume, as is required by the protocol. Because such a large proportion of children were reported to undergo only one or two body volume measurements, this suggests that behavioral compliance was low.…”

“…Inclusion of children in the validation study that could not complete all three repetitions of the test likely contributed to the poor agreement between methods. Second, Rosendale and Bartok (2) used different lean mass hydration reference data for the two methods (Butte coefficients for the Pediatric Option (3), and Fomon coefficients (4) for the comparison method); use of the same coefficients is ideal when comparing methods. Last, the study by Fields and Allison (1) used the four-compartment model as the criterion method for comparison to the Pediatric Options whereas Rosendale and Bartok used total body water.…”

Assessing Early Growth and Adiposity: Report from an EarlyNutrition Academy Workshop

“…The available data from a limited number of studies evaluating the performance of the method in comparison with other techniques or standards support the conclusion that this method is accurate, reliable and produces reproducible results [49]. A modified version of the adult BOD POD ADP instrument has recently been validated for use in infants and children aged 6-48 months [50]. …”