title: Skeletal muscle mass in hospitalized elderly patients: comparison of measurements by single-frequency BIA and DXA.
abstract: OBJECTIVE
  There is increasing interest in estimating skeletal muscle mass (SMM) in clinical practice. We aimed to validate a bioelectrical impedance analysis (BIA) prediction equation for SMM, developed in a different healthy elderly population, in a population of hospital patients aged 70 and over, by comparison with dual-energy X-ray absorptiometry (DXA) SMM estimates. Comparison was also made with two other previously published BIA muscle prediction equations.
  
  
  METHODS
  Muscle measurements by BIA and DXA were compared in 117 patients with a range of clinical conditions (45 female, 72 male, mean age 75 years).
  
  
  RESULTS
  The BIA equation used yielded an accurate estimate of DXA-derived SMM. Mean (SD) difference was 0.26(1.79) kg (ns). The two other BIA equations over-estimated SMM compared to DXA (both p < 0.001), but all equations were highly correlated.
  
  
  CONCLUSIONS
  The BIA equation used, developed in a different healthy elderly population, gave an accurate estimate of DXA-derived SMM in a population with various clinical disorders. BIA appears potentially capable to estimate SMM in clinical disorders, but the optimal approach to its use for this purpose requires further investigation.
authors.affiliation: Clinical Nutrition Unit, Sahlgrenska University Hospital, Bruna stråket 11 plan 4, S-413 45 Gothenburg, Sweden. Electronic address: ingvar.bosaeus@nutrition.gu.se.
authors.forename: Ingvar
authors.initials: I
authors.lastname: Bosaeus
authors.affiliation: Dept. of Medicine, Southern Clinical School, Monash University, Clayton, Victoria, Australia. Electronic address: gisela.wilcox@monash.edu.
authors.forename: Gisela
authors.initials: G
authors.lastname: Wilcox
authors.affiliation: Clinical Nutrition Unit, Sahlgrenska University Hospital, Bruna stråket 11 plan 4, S-413 45 Gothenburg, Sweden. Electronic address: elisabet.rothenberg@vgregion.se.
authors.forename: Elisabet
authors.initials: E
authors.lastname: Rothenberg
authors.affiliation: Dept. of Medicine, Southern Clinical School, Monash University, Clayton, Victoria, Australia. Electronic address: boyd.strauss@monash.edu.
authors.forename: Boyd J
authors.initials: BJ
authors.lastname: Strauss
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods*; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition; D017097:Electric Impedance; D005260:Female; D006760:Hospitalization; D006801:Humans; D016014:Linear Models; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*
keywords: Bioimpedance analysis; Body composition; Elderly; Method comparison; Sarcopenia