Evaluation of appendicular lean mass using bio impedance in persons aged 80+: A new equation based on the BUTTERFLY-study

S. Vermeiren, D. Beckwée, R. Vella-Azzopardi, I. Beyer, V. Knoop, B. Jansen, A. Delaere, A. Antoine, I. Bautmans, A. Scafoglieri, Ivan Bautmans, Dominque Verté, Ingo Beyer, Mirko Petrovic, Liesbeth de Donder, Tinie Kardol, Gina Rossi, Peter Clarys, Aldo Scafoglieri, Erik CattryssePaul de Hert, Bart Jansen

Research output: Contribution to journalArticleAcademicpeer-review


Background: To date, the accuracy of bio-impedance (BIA) to assess body composition & sarcopenia in persons aged 80 and over remains unclear. Objective: We aimed to evaluate the agreement between dual energy X-ray absorptiometry (DXA) and BIA equations to determine lean mass, as well as their suitability to identify sarcopenia. Design: 174 community dwelling well-functioning persons (83 women, 91 men) aged 80 and over were included. Appendicular lean mass (ALM) was predicted using BIA-based equations available in literature, and compared to DXA outcomes. Through cross-validation and stepwise multiple linear regression, a new ALM-formula was generated suitable for this population. Results: Literature-based BIA equations systematically overestimated ALM. The new prediction formula that we propose for the 80+ is: ALM = 0,827+(0,19*Impedance Index)+(2,101*Sex)+(0,079*Weight); R2 = 0,888; SEE = 1,450 kg. Sarcopenia classification based on our new BIA equation for ALM showed better agreement with DXA (k ≥ 0,454) compared to literature-based BIA equations (k < 0,368). Conclusions: Despite the high correlation between both methods, literature-based BIA equations consistently overestimate ALM compared to DXA in persons aged 80 and over. We proposed a new equation for ALM, reaching higher agreement with DXA and thus improving the accuracy of BIA for this specific age group.
Original languageEnglish
Pages (from-to)1756-1764
JournalClinical Nutrition
Issue number4
Publication statusPublished - 1 Aug 2019
Externally publishedYes

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