Body composition analysis by dual X‐ray absorptiometry:in vivoandin vitrocomparison of three different fan‐beam instruments

Abstract

Background. Dual X‐ray absorptiometry (DXA) is the preferred method for measuring body composition in clinical practice, but interchange between devices may pose problems with the interpretation of results. Objective. To establish conversion equations for body composition variables between three fan‐beam DXA systems. Methods. Body composition was assessed in 21 subjects using Lunar Expert (Expert), Lunar Prodigy (Prodigy) and Hologic Delphi W (Delphi). Weekly measurements of Hologic whole body phantom 164 were performed. Results. There were no significant differences between DXA‐measured means of body weight, fat mass and lean body mass. Bland‐Altman analysis revealed that Lunar Expert increasingly overestimated fat mass with increasing total mass (ppp<0.001). Standard error of estimate (SEE) for the slopes ranged from 0.20% to 2.10%. Phantom studies revealed stable instrument function with CV% commonly<2%, except for lean mass for Delphi (5.5%). Conclusions. Despite the significant differences in measurement of body composition between DXA fan‐beam instruments, clinically relevant conversion factors can be established.