title: Prevalence of low muscle mass according to body mass index in older adults.
abstract: OBJECTIVE
  Low muscle mass has been associated with increased morbi-mortality and should be identified for optimizing preventive and therapeutic strategies. This study evaluates the prevalence of bioelectrical impedance analysis (BIA)-derived low muscle mass in older persons using definitions found through a systematic literature search and determines the link between body mass index (BMI) and low muscle mass.
  
  
  METHODS
  We performed a systematic search of trials involving ≥100 persons that derived low muscle mass from BIA and reported cut-offs for low muscle mass normalized for body height or weight. These cut-offs were applied to all adults ≥65 y who underwent a BIA measurement at Geneva University Hospital between 1990 and 2011 (N = 3181). The association between BMI and low muscle mass was evaluated through multivariate logistic regressions.
  
  
  RESULTS
  We identified 15 cut-offs based on the fat-free mass index (FFMI), skeletal muscle index (SMI), or skeletal muscle percentage (SMP). Depending on the definition, the prevalence of low muscle mass was 17% to 68% in women and 17% to 85% in men. The risk of low muscle mass increased with a BMI <18.5 kg/m2when using cut-offs based on FFMI (odds ratio [OR] ♀ 14.28-24.04/♂ 25.42-50.64) or SMI (OR ♀ 3.56-4.56/♂ 7.07-8.87) and decreased with a BMI ≥25 kg/m2(FFMI: OR ♀ 0.03-0.04/♂ 0.01-0.04; SMI: OR ♀ 0.18-0.25/♂ 0.14-0.18). The opposite association appeared between BMI and cut-offs based on SMP.
  
  
  CONCLUSIONS
  The prevalence of low muscle mass varies widely depending on the definition, especially in persons with BMI <18.5 or ≥25 kg/m2.
authors.affiliation: Medical Rehabilitation, Department of Rehabilitation and Palliative Medicine, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
authors.forename: Christophe E
authors.initials: CE
authors.lastname: Graf
authors.affiliation: Clinical Nutrition, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
authors.forename: Claude
authors.initials: C
authors.lastname: Pichard
authors.affiliation: Geriatrics, Department of Internal Medicine, Rehabilitation and Geriatrics, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
authors.forename: François R
authors.initials: FR
authors.lastname: Herrmann
authors.affiliation: Friedrich-Alexander-University Erlangen-Nürnberg, Nürnberg, Germany.
authors.forename: Cornel C
authors.initials: CC
authors.lastname: Sieber
authors.affiliation: Geriatrics, Department of Internal Medicine, Rehabilitation and Geriatrics, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
authors.forename: Dina
authors.initials: D
authors.lastname: Zekry
authors.affiliation: Clinical Nutrition, Geneva University Hospitals and University of Geneva, Geneva, Switzerland. Electronic address: Laurence.genton@hcuge.ch.
authors.forename: Laurence
authors.initials: L
authors.lastname: Genton
mesh_terms: D000368:Aged; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D017097:Electric Impedance; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D018482:Muscle, Skeletal / Q000502:physiology*; D015995:Prevalence; D012189:Retrospective Studies; D055948:Sarcopenia / Q000175:diagnosis* / Q000453:epidemiology*
keywords: Body composition; Elderly; Fat-free mass; Presarcopenia; Skeletal muscle mass