Comparison of Multifrequency Bioelectrical Impedance Analysis and Dual-Energy X-ray Absorptiometry Assessments in Outpatient Hemodialysis Patients

Background Malnutrition is common in hemodialysis patients and closely related to increased morbidity and mortality. As such, simple, reliable, and easily available methods of determining nutritional status and recognition of short-term changes in body composition are desirable for routine clinical practice. Study Design Diagnostic test study. Setting & Participants 53 stable adult hemodialysis patients attending for thrice-weekly outpatient hemodialysis in a university tertiary hospital dialysis center. Index Test Comparison of dual-energy x-ray absorptiometry (DEXA) and multifrequency bioelectrical impedance analysis (BIA) using a tetrapolar 8-point tactile electrode system as 2 index tests of body composition. Reference Test None. Results Assessment of whole-body composition showed that lean body mass measured using the 2 techniques correlated highly, with good method agreement shown using a Bland-Altman plot ( r = 0.92; P < 0.001; bias, +1 g [95% CI, −1,173 to 1,175]), as did fat mass ( r = 0.93; P < 0.001; bias, −157 g [95% CI, −1,251 to 937]). Similarly, segmental analysis of lean body mass showed strong correlations between lean body mass of the trunk and right and left legs with small bias ( r = 0.85, 0.89, and 0.86, respectively; P < 0.001; Bland-Altman bias, −859, +364, and +552 g, respectively), but weaker correlations for lean body mass for the right and left arm ( r = 0.69 and 0.75, respectively; P < 0.001; Bland-Altman bias, −240 and +12 g, respectively). Bone mineral content derived using multifrequency BIA overestimated that measured using DEXA ( r = 0.77; P < 0.001; bias, +530 g [95% CI, 422-638]). Limitations Retrospective study in a healthy ambulant outpatient cohort. Conclusions Compared with DEXA, multifrequency BIA appears to be a robust tool for measuring and monitoring total-body fat and lean body mass in hemodialysis patients; however, there is less agreement in bone mineral content assessment between the 2 methods.