title: Cutpoints for low appendicular lean mass that identify older adults with clinically significant weakness.
abstract: BACKGROUND
  Low lean mass is potentially clinically important in older persons, but criteria have not been empirically validated. As part of the FNIH (Foundation for the National Institutes of Health) Sarcopenia Project, this analysis sought to identify cutpoints in lean mass by dual-energy x-ray absorptiometry that discriminate the presence or absence of weakness (defined in a previous report in the series as grip strength <26kg in men and <16kg in women).
  
  
  METHODS
  In pooled cross-sectional data stratified by sex (7,582 men and 3,688 women), classification and regression tree (CART) analysis was used to derive cutpoints for appendicular lean body mass (ALM) that best discriminated the presence or absence of weakness. Mixed-effects logistic regression was used to quantify the strength of the association between lean mass category and weakness.
  
  
  RESULTS
  In primary analyses, CART models identified cutpoints for low lean mass (ALM <19.75kg in men and <15.02kg in women). Sensitivity analyses using ALM divided by body mass index (BMI: ALMBMI) identified a secondary definition (ALMBMI <0.789 in men and ALMBMI <0.512 in women). As expected, after accounting for study and age, low lean mass (compared with higher lean mass) was associated with weakness by both the primary (men, odds ratio [OR]: 6.9 [95% CI: 5.4, 8.9]; women, OR: 3.6 [95% CI: 2.9, 4.3]) and secondary definitions (men, OR: 4.3 [95% CI: 3.4, 5.5]; women, OR: 2.2 [95% CI: 1.8, 2.8]).
  
  
  CONCLUSIONS
  ALM cutpoints derived from a large, diverse sample of older adults identified lean mass thresholds below which older adults had a higher likelihood of weakness.
authors.affiliation: California Pacific Medical Center Research Institute, 185 Berry Street, Suite 5700, San Francisco, CA 94107-1762. pcawthon@sfcc-cpmc.net.
authors.forename: Peggy M
authors.initials: PM
authors.lastname: Cawthon
authors.forename: Katherine W
authors.initials: KW
authors.lastname: Peters
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Shardell
authors.forename: Robert R
authors.initials: RR
authors.lastname: McLean
authors.forename: Thuy-Tien L
authors.initials: TT
authors.lastname: Dam
authors.forename: Anne M
authors.initials: AM
authors.lastname: Kenny
authors.forename: Maren S
authors.initials: MS
authors.lastname: Fragala
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
authors.forename: Douglas P
authors.initials: DP
authors.lastname: Kiel
authors.forename: Jack M
authors.initials: JM
authors.lastname: Guralnik
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Kritchevsky
authors.forename: Maria T
authors.initials: MT
authors.lastname: Vassileva
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Studenski
authors.forename: Dawn E
authors.initials: DE
authors.lastname: Alley
mesh_terms: D015502:Absorptiometry, Photon; D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D018908:Muscle Weakness / Q000175:diagnosis* / Q000503:physiopathology*; D055948:Sarcopenia / Q000175:diagnosis / Q000503:physiopathology*; D012737:Sex Factors; D013851:Thinness / Q000175:diagnosis* / Q000503:physiopathology*; D014481:United States
keywords: Cutpoints.; Muscle; Sarcopenia
references.citation: Am J Epidemiol. 1979 Sep;110(3):281-90
references.pmid: 474565
references.citation: J Am Geriatr Soc. 2003 Nov;51(11):1602-9
references.pmid: 14687390
references.citation: Am J Epidemiol. 2004 Feb 15;159(4):413-21
references.pmid: 14769646
references.citation: Semin Nucl Med. 1997 Jul;27(3):210-28
references.pmid: 9224663
references.citation: Am J Epidemiol. 1998 Apr 15;147(8):755-63
references.pmid: 9554417
references.citation: Epidemiol Rev. 2013;35:51-65
references.pmid: 23221972
references.citation: Am J Prev Med. 2003 Oct;25(3):226-31
references.pmid: 14507529
references.citation: Age Ageing. 2010 Jul;39(4):412-23
references.pmid: 20392703
references.citation: J Nutr Health Aging. 2013 Jan;17(1):76-80
references.pmid: 23299384
references.citation: JAMA. 2005 May 4;293(17):2102-8
references.pmid: 15870413
references.citation: N Engl J Med. 1995 Mar 23;332(12):767-73
references.pmid: 7862179
references.citation: Contemp Clin Trials. 2005 Oct;26(5):569-85
references.pmid: 16084776
references.citation: J Am Geriatr Soc. 2003 Mar;51(3):323-30
references.pmid: 12588575
references.citation: J Gerontol A Biol Sci Med Sci. 2001 May;56(5):M266-72
references.pmid: 11320105
references.citation: J Am Geriatr Soc. 2010 Sep;58(9):1707-14
references.pmid: 20863330
references.citation: J Gerontol A Biol Sci Med Sci. 2014 May;69(5):559-66
references.pmid: 24737558
references.citation: J Am Med Dir Assoc. 2011 May;12(4):249-56
references.pmid: 21527165
references.citation: BMC Public Health. 2010 Mar 01;10:107
references.pmid: 20193082
references.citation: J Gerontol A Biol Sci Med Sci. 2014 May;69(5):584-90
references.pmid: 24737561
references.citation: J Gerontol A Biol Sci Med Sci. 2014 May;69(5):547-58
references.pmid: 24737557
references.citation: J Am Geriatr Soc. 2007 May;55(5):769-74
references.pmid: 17493199
references.citation: JAMA. 2003 Aug 27;290(8):1042-8
references.pmid: 12941676
references.citation: Osteoporos Int. 2005 Sep;16(9):1096-108
references.pmid: 15754082
references.citation: Am J Public Health Nations Health. 1951 Mar;41(3):279-81
references.pmid: 14819398
references.citation: J Am Geriatr Soc. 2003 Dec;51(12):1762-7
references.pmid: 14687355