Critical assessment of body-composition measurements in malnourished subjects with Crohn's disease: the role of bioelectric impedance analysis

Bioelectric impedance analysis (BIA) has been widely used for assessment of body composition in healthy subjects but has not been validated in malnourished patients. This study compared calculation of fat-free mass (FFM) by five methods to determine whether the currently used equations for total body water (TBW) as assessed by BIA were applicable to 19 malnourished patients with Crohn's disease. When compared with TBW assessed by H 2 18 O dilution, BIA was higher by 5.9±1.1% (P<0.005). A stepwise-multiple-regression equation was derived to validate BIA: TBW (kg)=0.25 (ht 2 /resistance) +0.29 (wt) +3.63 (r=0.97, SEE=0.28)