BACKGROUND & AIMS: Bioimpedance spectroscopy (BIS) offers the possibility to perform rapid estimates of fluid distribution and body composition. Few studies, however, have addressed the precision and biological variation in a pediatric population. Our objectives were to evaluate precision, variation within- and between-days for the BIS-determined parameters total body fluid, extra-cellular fluid, intra-cellular fluid, body cell mass, fat-free mass, extra-cellular resistance, intra-cellular resistance and percentage body fat using a Xitron 4200. METHODS: All 133 children (81 boys, 52 girls; 2.4-14.9 years) had one series measured on day one (precision population). Forty-four children had a second series on day one (within-day sub-population). Thirty-two children had a series measured on the next day (between-day sub-population). Each measurement series consisted of three repeated measurements. A linear mixed model was used for statistical analysis. RESULTS: The precision was 0.3-0.8% in children ≥6 years and 0.5-2.4% in children <6 years with a statistically significant difference between the two age-groups (p<0.001). Within-day variation was 1.1-2.8% and between-day variation 2.4-5.7%. Total variation and reference change values are reported. CONCLUSION: The Xitron 4200 has a very good but age-dependent precision. The median value of three repeated measurements is recommended in order to avoid incorrect measurements.
BACKGROUND & AIMS: Bioimpedance spectroscopy (BIS) offers the possibility to perform rapid estimates of fluid distribution and body composition. Few studies, however, have addressed the precision and biological variation in a pediatric population. Our objectives were to evaluate precision, variation within- and between-days for the BIS-determined parameters total body fluid, extra-cellular fluid, intra-cellular fluid, body cell mass, fat-free mass, extra-cellular resistance, intra-cellular resistance and percentage body fat using a Xitron 4200. METHODS: All 133 children (81 boys, 52 girls; 2.4-14.9 years) had one series measured on day one (precision population). Forty-four children had a second series on day one (within-day sub-population). Thirty-two children had a series measured on the next day (between-day sub-population). Each measurement series consisted of three repeated measurements. A linear mixed model was used for statistical analysis. RESULTS: The precision was 0.3-0.8% in children ≥6 years and 0.5-2.4% in children <6 years with a statistically significant difference between the two age-groups (p<0.001). Within-day variation was 1.1-2.8% and between-day variation 2.4-5.7%. Total variation and reference change values are reported. CONCLUSION: The Xitron 4200 has a very good but age-dependent precision. The median value of three repeated measurements is recommended in order to avoid incorrect measurements.
Authors: John A Shepherd; Steven B Heymsfield; Shane A Norris; Leanne M Redman; Leigh C Ward; Christine Slater Journal: Obesity (Silver Spring) Date: 2016-04-07 Impact factor: 5.002