Do muscle mass, muscle density, strength, and physical function similarly influence risk of hospitalization in older adults?
OBJECTIVE
To examine the association between strength, function, lean mass, muscle density, and risk of hospitalization.


METHODS
Prospective cohort study.


METHODS
Two U.S. clinical centers.


METHODS
Adults aged 70 to 80 (N=3,011) from the Health, Aging and Body Composition Study.


METHODS
Measurements were of grip strength, knee extension strength, lean mass, walking speed, and chair stand pace. Thigh computed tomography scans assessed muscle area and density (a proxy for muscle fat infiltration). Hospitalizations were confirmed by local review of medical records. Negative binomial regression models estimated incident rate ratios (IRRs) of hospitalization for race- and sex-specific quartiles of each muscle and function parameter separately. Multivariate models adjusted for age, body mass index, health status, and coexisting medical conditions.


RESULTS
During an average 4.7 years of follow-up, 1,678 (55.7%) participants experienced one or more hospitalizations. Participants in the lowest quartile of muscle density were more likely to be subsequently hospitalized (multivariate IRR=1.47, 95% confidence interval (CI)=1.24-1.73) than those in the highest quartile. Similarly, participants with the weakest grip strength were at greater risk of hospitalization (multivariate IRR=1.52, 95% CI=1.30-1.78, Q1 vs. Q4). Comparable results were seen for knee strength, walking pace, and chair stands pace. Lean mass and muscle area were not associated with risk of hospitalization.


CONCLUSIONS
Weak strength, poor function, and low muscle density, but not muscle size or lean mass, were associated with greater risk of hospitalization. Interventions to reduce the disease burden associated with sarcopenia should focus on increasing muscle strength and improving physical function rather than simply increasing lean mass.
Cawthon
Peggy Mannen
PM
Research Institute, California Pacific Medical Center, San Francisco, California 94107, USA. pcawthon@sfcc-cpmc.net
Fox
Kathleen M
KM
Gandra
Shravanthi R
SR
Delmonico
Matthew J
MJ
Chiou
Chiun-Fang
CF
Anthony
Mary S
MS
Sewall
Ase
A
Goodpaster
Bret
B
Satterfield
Suzanne
S
Cummings
Steven R
SR
Harris
Tamara B
TB
D015502:Absorptiometry, Photon; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition / Q000502:physiology*; D005260:Female; D015577:Geriatric Assessment; D018737:Hand Strength / Q000502:physiology; D006760:Hospitalization; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D006278:Medicare; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology* / Q000503:physiopathology; D016012:Poisson Distribution; D011446:Prospective Studies; D012044:Regression Analysis; D012306:Risk; D013848:Thigh; D014057:Tomography, X-Ray Computed; D019415:Torque; D014481:United States; D016138:Walking / Q000502:physiology*
Arch Intern Med. 1996 Mar 25;156(6):645-52
8629876
J Gerontol A Biol Sci Med Sci. 2006 Oct;61(10):1059-64
17077199
N Engl J Med. 1988 Dec 29;319(26):1701-7
3205267
JAMA. 2004 Nov 3;292(17):2115-24
15523072
J Am Geriatr Soc. 2004 Jul;52(7):1121-9
15209650
Am J Med. 2004 Jun 15;116(12):807-15
15178496
J Am Geriatr Soc. 1990 Dec;38(12):1296-303
2123911
JAMA. 1997 Mar 5;277(9):728-34
9042845
J Am Geriatr Soc. 2002 May;50(5):897-904
12028178
J Appl Physiol (1985). 2000 Jul;89(1):104-10
10904041
J Bone Miner Res. 2007 Feb;22(2):211-9
17059373
J Am Geriatr Soc. 2000 Apr;48(4):381-6
10798463
J Am Geriatr Soc. 2003 Nov;51(11):1602-9
14687390
Am J Epidemiol. 1996 Jun 1;143(11):1129-36
8633602
J Appl Physiol (1985). 2001 Jun;90(6):2157-65
11356778
MMWR Recomm Rep. 2000 Mar 31;49(RR-2):3-12
15580729
J Am Geriatr Soc. 2004 Jan;52(1):80-5
14687319
J Am Geriatr Soc. 2000 Dec;48(12):1618-25
11129752
J Am Geriatr Soc. 2005 Oct;53(10):1675-80
16181165
J Gerontol A Biol Sci Med Sci. 2005 Mar;60(3):324-33
15860469
Arch Intern Med. 2005 Apr 11;165(7):777-83
15824297
J Clin Epidemiol. 2003 Jun;56(6):559-64
12873651
J Gerontol A Biol Sci Med Sci. 2000 Nov;55(11):M691-7
11078100
J Bone Miner Res. 2008 Jul;23(7):1037-44
18302496
Biochim Biophys Acta. 2002 Dec 30;1585(2-3):202-12
12531555
N Engl J Med. 1995 Mar 23;332(12):767-73
7862179
J Am Geriatr Soc. 2003 Mar;51(3):323-30
12588575
J Hand Ther. 1993 Oct-Dec;6(4):259-62
8124439