Whole body air displacement plethysmography compared with hydrodensitometry for body composition analysis

Aims-To assess the acceptability and feasibility of whole body air displace ment plethysmography in children and to determine its precision and agreeme nt with hydrodensitometry, an appropriate reference method. Methods-Age specific two component model equations were used to predict fat mass from body density in 22 children aged 8-12 years and in 1.0 adults fo r comparison of methods. Precision for each method was established from dup licate measurements. Results-Plethysmography was accepted more readily than hydrodensitometry (1 00% v 69% provided duplicate measurements). Precision for fat mass in child ren was 0.38 kg by plethysmography and 0.68 kg by hydrodensitometry, and re sults were similar in adults. The mean (SD) fat mass in children was 6.9 kg (4.0) and 6.7 kg (4.2) by plethysmography and hydrodensitometry, respectiv ely, but 95% limits of agreement between methods were large (-4.1 kg to 3.5 kg fat). Conclusion-Plethysmography was more readily accepted and had better precisi on than hydrodensitometry. It also provided similar body composition result s for the group but not for all individual children.