title: HIV Infection Is Associated with Increased Fatty Infiltration of the Thigh Muscle with Aging Independent of Fat Distribution.
abstract: BACKGROUND
  Lower muscle density on computed tomography (CT) provides a measure of fatty infiltration of muscle, an aspect of muscle quality that has been associated with metabolic abnormalities, weakness, decreased mobility, and increased fracture risk in older adults. We assessed the cross-sectional relationship between HIV serostatus, age, thigh muscle attenuation, and thigh muscle cross-sectional area (CSA).
  
  
  METHODS
  Mean CT-quantified Hounsfield units (HU) of the thigh muscle bundle and CSA were evaluated in 368 HIV-infected and 145 HIV-uninfected men enrolled in the Multicenter AIDS Cohort Study (MACS) Cardiovascular Substudy using multivariable linear regression. Models all were adjusted for HIV serostatus, age, race, and body mass index (BMI); each model was further adjusted for covariates that differed by HIV serostatus, including insulin resistance, hepatitis C, malignancy, smoking, alcohol use, and self-reported limitation in physical activity.
  
  
  RESULTS
  HIV-infected men had greater thigh muscle CSA (p<0.001) but lower muscle density (p<0.001) compared to HIV-uninfected men. Muscle density remained lower in HIV-infected men (p = 0.001) when abdominal visceral adiposity, and thigh subcutaneous adipose tissue area were substituted for BMI in a multivariable model. Muscle density decreased by 0.16 HU per year (p<0.001) of increasing age among the HIV-infected men, but not in the HIV-uninfected men (HIV x age interaction -0.20 HU; p = 0.002).
  
  
  CONCLUSIONS
  HIV-infected men had lower thigh muscle density compared to HIV-uninfected men, and a more pronounced decline with increasing age, indicative of greater fatty infiltration. These findings suggest that lower muscle quality among HIV-infected persons may be a risk factor for impairments in physical function with aging.
authors.affiliation: Johns Hopkins University, Baltimore, United States of America.
authors.forename: Javzandulam
authors.initials: J
authors.lastname: Natsag
authors.affiliation: University of Colorado Anschutz Medical Campus, Aurora, United States of America.
authors.forename: Kristine M
authors.identifier: http://orcid.org/0000-0003-0808-6729
authors.initials: KM
authors.lastname: Erlandson
authors.affiliation: Johns Hopkins University, Baltimore, United States of America.
authors.forename: Deborah E
authors.initials: DE
authors.lastname: Sellmeyer
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, United States of America.
authors.forename: Sabina A
authors.initials: SA
authors.lastname: Haberlen
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, United States of America.
authors.forename: Joseph
authors.initials: J
authors.lastname: Margolick
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, United States of America.
authors.forename: Lisa P
authors.initials: LP
authors.lastname: Jacobson
authors.affiliation: Northwestern University Feinberg School of Medicine, Chicago, United States of America.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Palella
authors.affiliation: The Ohio State University, Columbus, United States of America.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Koletar
authors.affiliation: David Geffen School of Medicine at UCLA, Los Angeles, United States of America.
authors.forename: Jordan E
authors.initials: JE
authors.lastname: Lake
authors.affiliation: Johns Hopkins University, Baltimore, United States of America.
authors.forename: Wendy S
authors.initials: WS
authors.lastname: Post
authors.affiliation: Johns Hopkins University, Baltimore, United States of America.
authors.forename: Todd T
authors.initials: TT
authors.lastname: Brown
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology*; D001823:Body Composition / Q000502:physiology; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000378:metabolism* / Q000503:physiopathology*; D006801:Humans; D050356:Lipid Metabolism / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D050151:Subcutaneous Fat / Q000378:metabolism; D013848:Thigh