title: The significance of body mass index in calculating the cut-off points for low muscle mass in the elderly: methodological issues.
abstract: OBJECTIVE
  Cut-off points (COPs) for appendicular lean mass (ALM) index, essential to define low muscle mass (LMM) in the elderly, have never been officially defined for Poland. The aim of the study was to establish them. Additionally, the significance of body mass index (BMI) for correctly defining the COPs in a young, healthy reference group was assessed.
  
  
  METHODS
  The study was composed of reference group (n = 1113) and the elderly group (n = 200). In all subjects, body composition was assessed by bioimpedance analysis, and ALM index was calculated. Next, COPs (kg/m(2)) were set up for the whole reference group and for particular subgroups with different BMIs separately. They were used to diagnose sarcopenia in the elderly.
  
  
  RESULTS
  COP for all young females was 5.37 (COP-F), while it was equal to 5.52 (COP-F2) when only those with a recommended BMI (18.50-24.99 kg/m(2)) were taken into consideration. For males, it was 7.32 and 7.29, respectively. Only 7% of elderly females had LMM based on COP-F and 15% had LMM based on COP-F2 (P < 0.05); for males, the percentages were 18% and 16%, respectively.
  
  
  CONCLUSIONS
  COPs for LMM for Poland are 5.52 kg/m(2) (females) and 7.29 kg/m(2) (males). The reference group BMI is an important factor in establishing COPs for low muscle mass.
authors.affiliation: Department of Palliative Medicine, Poznan University of Medical Sciences, Osiedle Rusa 25a, 61-245 Poznan, Poland.
authors.forename: Roma
authors.identifier: 0000-0002-6770-7321
authors.initials: R
authors.lastname: Krzymińska-Siemaszko
authors.affiliation: Department of Pathophysiology, Poznan University of Medical Sciences, 8 Rokietnicka Street, 60-806 Poznan, Poland.
authors.forename: Natasza
authors.identifier: 0000-0003-4574-6773
authors.initials: N
authors.lastname: Czepulis
authors.affiliation: Department of Adult Psychiatry, Poznan University of Medical Sciences, 27/33 Szpitalna Street, 60-572 Poznan, Poland.
authors.forename: Aleksandra
authors.identifier: 0000-0002-5759-5151
authors.initials: A
authors.lastname: Suwalska
authors.affiliation: Department of Bionics, University of Arts, Aleje Marcinkowskiego 29, 60-967 Poznan, Poland ; Department of Physiotherapy and Biological Renovation, Stanislaw Wojciechowski Higher Vocational State School, 4 Nowy Swiat Street, 62-800 Kalisz, Poland ; Department of Biomechanics, University School of Physical Education, 27/39 Krolowej Jadwigi Street, 61-871 Poznan, Poland.
authors.forename: Lechoslaw B
authors.initials: LB
authors.lastname: Dworak
authors.affiliation: Department of Biomechanics, University School of Physical Education, 27/39 Krolowej Jadwigi Street, 61-871 Poznan, Poland.
authors.forename: Anna
authors.identifier: 0000-0003-1163-3973
authors.initials: A
authors.lastname: Fryzowicz
authors.affiliation: Department of Physiotherapy and Biological Renovation, Stanislaw Wojciechowski Higher Vocational State School, 4 Nowy Swiat Street, 62-800 Kalisz, Poland.
authors.forename: Beata
authors.identifier: 0000-0001-7573-834X
authors.initials: B
authors.lastname: Madej-Dziechciarow
authors.affiliation: Department of Palliative Medicine, Poznan University of Medical Sciences, Osiedle Rusa 25a, 61-245 Poznan, Poland.
authors.forename: Katarzyna
authors.identifier: 0000-0003-4017-3013
authors.initials: K
authors.lastname: Wieczorowska-Tobis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology*; D011044:Poland