title: Chronic inflammation is associated with low physical function in older adults across multiple comorbidities.
abstract: BACKGROUND
  Chronic subclinical inflammation may contribute to impaired physical function in older adults; however, more data are needed to determine whether inflammation is a common mechanism for functional decline, independent of disease or health status.
  
  
  METHODS
  We examined associations between physical function and inflammatory biomarkers in 542 older men and women enrolled in four clinical studies at Wake Forest University between 2001 and 2006. All participants were at least 55 years and had chronic obstructive pulmonary disease, congestive heart failure, high cardiovascular risk, or self-reported physical disability. Uniform clinical assessments were used across studies, including grip strength; a Short Physical Performance Battery (SPPB; includes balance, 4-m walk, and repeated chair stands); inflammatory biomarker assays for interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and C-reactive protein (CRP); and anthropometric measures.
  
  
  RESULTS
  Higher levels of CRP and IL-6, but not TNF-alpha, were associated with lower grip strength and SPPB scores and longer times to complete the 4-m walk and repeated chair stands tests, independent of age, gender, and race. More importantly, these relationships were generally independent of disease status. Further adjustment for fat mass, lean mass, or percent body fat altered some of these relationships but did not significantly change the overall results.
  
  
  CONCLUSIONS
  Elevated CRP and IL-6 levels are associated with poorer physical function in older adults with various comorbidities, as assessed by a common battery of clinical assessments. Chronic subclinical inflammation may be a marker of functional limitations in older persons across several diseases/health conditions.
authors.affiliation: Section on Gerontology and Geriatric Medicine, Department of Internal Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA. tbrinkle@wfubmc.edu
authors.forename: Tina E
authors.initials: TE
authors.lastname: Brinkley
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Leng
authors.forename: Michael E
authors.initials: ME
authors.lastname: Miller
authors.forename: Dalane W
authors.initials: DW
authors.lastname: Kitzman
authors.forename: Marco
authors.initials: M
authors.lastname: Pahor
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Berry
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Marsh
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Kritchevsky
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Nicklas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001823:Body Composition; D002097:C-Reactive Protein / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000453:epidemiology; D002908:Chronic Disease; D015331:Cohort Studies; D015897:Comorbidity; D015444:Exercise / Q000502:physiology; D005260:Female; D015577:Geriatric Assessment; D018737:Hand Strength; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D018836:Inflammation Mediators / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010809:Physical Fitness / Q000502:physiology*; D011336:Probability; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology; D012680:Sensitivity and Specificity; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D018836:Inflammation Mediators; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein