Estimates of the precision of regional and whole body composition by dual-energy x-ray absorptiometry in persons with chronic spinal cord injury.

STUDY DESIGN: Repeated measures design.

OBJECTIVES: To determine the reproducibility of total-body and regional-body composition assessments from a total-body scan using dual-energy x-ray absorptiometry (DXA) in persons with spinal cord injury (SCI).

METHODS: Twenty-four individuals with SCI completed within-day short-term precision testing by repositioning study participants between scans. An additional and separate cohort of 22 individuals with SCI were scanned twice on a GE-Lunar DXA scanner separated by a 4-week interval to assess the long-term precision assessment. The root mean square coefficient of variation percent (RMS-CV%) values for the regional and total body composition was calculated.

RESULTS: For the same day, short-term precision assessment, the RMS-CV% for each region did not exceed 5.6, 2.7, 3.8, 6.5, 5.8, and 2.3% for arms, legs, trunk, android and gynoid regions, and total body mass, respectively. In the long-term precision assessment, the RMS-CV% for each region did not exceed 6.0, 3.0, 4.4, 8.2, 3.4, and 2.0% for arms, legs, trunk, android, gynoid, and total body mass. Moreover, the interclass-correlation coefficient in the long-term precision group demonstrated excellent linear agreement between repeat scans for all regions (r > 0.97).

CONCLUSIONS: The precision error of the total body composition variables in our SCI cohort was similar to those reported in the literature for nondisabled individuals, and the precision errors of the regional body composition compartments were notably higher, but similar to the regional precision errors reported in the general population.