Anthropometry, bioimpedance and densitometry: Comparative methods for lean mass body analysis in elderly outpatients...

To evaluate lean mass index (LMI) measured by bioimpedance (BIA) and anthropometry compared to densitometry (DXA) in elderly outpatients from a tertiary care hospital.

Participants were over 60-year-old men, presenting no dementia or disability, from a tertiary geriatric ambulatory. LMI obtained by BIA, anthropometry and DXA were submitted to Baumgartner, Janssen and Delmonico calculations respectively. Sarcopenia was calculated as LMI by DXA and handgrip strength. Data were analyzed by T student's test, ANOVA for repeated measures and pos hoc Bonferroni test, Pearson's correlation test, regression equation and Bland Altman analysis, ROC curve and contingency table 2 × 2 for sensitivity, specificity and predictive values.

A total of 92 participants completed the study. Most of them were married, aged 72.9 ± 6.6, lived a sedentary lifestyle, presented multiple morbidities, and in use of polypharmacy. Appendicular lean mass was lower in sarcopenic participants when compared to that in nonsarcopenic ones (20.2 kg/m² and 23 kg/m² respectively, p < 0.0001). BIA sensitivity, specificity and correlation to DXA were 37%, 98% and r = 0.81 (p < 0.001), and for anthropometry 67%, 92% and r = 0.77 (p < 0.0001) respectively. Bland Altman's analysis showed congruence between methods and DXA (anthropometry: bias = -0,05 ± 0,66, limits of agreement (LoA) = -1.37 and 1.26; BIA: bias = 2,2; LoA = 0,7 and 3,7).

Aging and multiple chronic and degenerative morbidities affect LM in vulnerable elderly patients. Both anthropometry and BIA, are accurate to measure LMI independently in this population but Anthropometry presented better agreement to DXA than Bioimpedance and has the advantage of lower price, easier application and cheaper equipment to be applied.