title: An anthropometric prediction equation for appendicular skeletal muscle mass in combination with a measure of muscle function to screen for sarcopenia in primary and aged care.
abstract: OBJECTIVE
  Sarcopenia is the presence of low muscle mass and poor physical function. We have developed an anthropometric prediction equation (PE). We compared the accuracy of our previously developed anthropometric prediction equation (PE) to dual absorptiometry x-ray (DXA) in predicting low muscle mass and sarcopenia.
  
  
  METHODS
  Cross-sectional study design.
  
  
  METHODS
  Community dwelling.
  
  
  METHODS
  Men and women aged 65 years and older.
  
  
  METHODS
  Gender-specific low muscle mass cutoffs were identified using the lowest 20% of the skeletal muscle index (SMI) where muscle mass was determined using PE in 611 men and 375 women aged 65 years and older. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of PE derived low muscle mass were compared with DXA-derived low muscle mass. The cohort was randomized into a development and validation group to identify various cutoffs for low muscle mass via the PE method and test its performance against the DXA method.
  
  
  RESULTS
  The PE cutoff for low muscle mass was less than 8.05 kg/m(2) in men and less than 5.35 kg/m(2) in women. On validation of various cutoffs with improving sensitivity values from 70% to 97%, specificity increased from 45.5% to 85.7%, PPV increased from 31.3% to 56.9%, and NPV increased from 93.0% to 98.6% in men. In women, specificity improved from 42% to 72%, PPV reduced from 56.9% to 31.3%, and NPV improved from 93.0% to 98.6%. When the PE method was combined with a measure of muscle performance, a similar pattern of performance was observed.
  
  
  CONCLUSIONS
  The PE when combined with a measure of muscle function to create a screening tool performs as a "rule-out" test with high sensitivity values and NPVs.
authors.affiliation: Aged and Extended Care Services, The Queen Elizabeth Hospital, Central Adelaide Local Health Network, South Australia, Australia; Adelaide Geriatrics Training and Research with Aged Care (G-TRAC) Centre, School of Medicine, Faculty of Health Science, University of Adelaide, Adelaide, South Australia, Australia; School of Medicine, Faculty of Health Science, University of Adelaide, Adelaide, South Australia, Australia. Electronic address: solomon.yu@adelaide.edu.au.
authors.forename: Solomon
authors.initials: S
authors.lastname: Yu
authors.affiliation: School of Medicine, Faculty of Health Science, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Sarah
authors.initials: S
authors.lastname: Appleton
authors.affiliation: School of Medicine, Faculty of Health Science, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Ian
authors.initials: I
authors.lastname: Chapman
authors.affiliation: School of Medicine, Faculty of Health Science, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Adams
authors.affiliation: School of Medicine, Faculty of Health Science, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Gary
authors.initials: G
authors.lastname: Wittert
authors.affiliation: Department of Anaesthesia, The Queen Elizabeth Hospital, Central Adelaide Local Health Network, South Australia, Australia.
authors.forename: Thavarajah
authors.initials: T
authors.lastname: Visvanathan
authors.affiliation: Aged and Extended Care Services, The Queen Elizabeth Hospital, Central Adelaide Local Health Network, South Australia, Australia; Adelaide Geriatrics Training and Research with Aged Care (G-TRAC) Centre, School of Medicine, Faculty of Health Science, University of Adelaide, Adelaide, South Australia, Australia; School of Medicine, Faculty of Health Science, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Renuka
authors.initials: R
authors.lastname: Visvanathan
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000886:Anthropometry / Q000379:methods*; D001823:Body Composition; D003430:Cross-Sectional Studies; D005260:Female; D015577:Geriatric Assessment / Q000379:methods*; D006801:Humans; D008297:Male; D015233:Models, Statistical; D018482:Muscle, Skeletal / Q000473:pathology; D011237:Predictive Value of Tests; D011320:Primary Health Care; D055948:Sarcopenia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D012680:Sensitivity and Specificity
keywords: Prediction equation; older people; sarcopenia; sensitivity and specificity