title: Quantitative computed tomography measures of pectoralis muscle area and disease severity in chronic obstructive pulmonary disease. A cross-sectional study.
abstract: BACKGROUND
  Muscle wasting in chronic obstructive pulmonary disease (COPD) is associated with a poor prognosis and is not readily assessed by measures of body mass index (BMI). BMI does not discriminate between relative proportions of adipose tissue and lean muscle and may be insensitive to early pathologic changes in body composition. Computed tomography (CT)-based assessments of the pectoralis muscles may provide insight into the clinical significance of skeletal muscles in smokers.
  
  
  OBJECTIVE
  We hypothesized that objective assessment of the pectoralis muscle area on chest CT scans provides information that is clinically relevant and independent of BMI.
  
  
  METHODS
  Data from the ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) Study (n = 73) were used to assess the relationship between pectoralis muscle area and fat-free mass. We then used data in a subset (n = 966) of a larger cohort, the COPDGene (COPD Genetic Epidemiology) Study, to explore the relationship between pectoralis muscle area and COPD-related traits.
  
  
  RESULTS
  We first investigated the correlation between pectoralis muscle area and fat-free mass, using data from a subset of participants in the ECLIPSE Study. We then further investigated pectoralis muscle area in COPDGene Study participants and found that higher pectoralis muscle area values were associated with greater height, male sex, and younger age. On subsequent clinical correlation, compared with BMI, pectoralis muscle area was more significantly associated with COPD-related traits, including spirometric measures, dyspnea, and 6-minute-walk distance (6MWD). For example, on average, each 10-cm(2) increase in pectoralis muscle area was associated with a 0.8-unit decrease in the BODE (Body mass index, Obstruction, Dyspnea, Exercise) index (95% confidence interval, -1.0 to -0.6; P < 0.001). Furthermore, statistically significant associations between pectoralis muscle area and COPD-related traits remained even after adjustment for BMI.
  
  
  CONCLUSIONS
  CT-derived pectoralis muscle area provides relevant indices of COPD morbidity that may be more predictive of important COPD-related traits than BMI. However, the relationship with clinically relevant outcomes such as hospitalization and death requires additional investigation. Pectoralis muscle area is a convenient measure that can be collected in the clinical setting in addition to BMI.
authors.affiliation: 1 Channing Division of Network Medicine, Harvard Medical School, Boston, Massachusetts.
authors.forename: Merry-Lynn N
authors.initials: ML
authors.lastname: McDonald
authors.forename: Alejandro A
authors.initials: AA
authors.lastname: Diaz
authors.forename: James C
authors.initials: JC
authors.lastname: Ross
authors.forename: Raul
authors.initials: R
authors.lastname: San Jose Estepar
authors.forename: Linfu
authors.initials: L
authors.lastname: Zhou
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Regan
authors.forename: Eric
authors.initials: E
authors.lastname: Eckbo
authors.forename: Nina
authors.initials: N
authors.lastname: Muralidhar
authors.forename: Carolyn E
authors.initials: CE
authors.lastname: Come
authors.forename: Michael H
authors.initials: MH
authors.lastname: Cho
authors.forename: Craig P
authors.initials: CP
authors.lastname: Hersh
authors.forename: Christoph
authors.initials: C
authors.lastname: Lange
authors.forename: Emiel
authors.initials: E
authors.lastname: Wouters
authors.forename: Richard H
authors.initials: RH
authors.lastname: Casaburi
authors.forename: Harvey O
authors.initials: HO
authors.lastname: Coxson
authors.forename: William
authors.initials: W
authors.lastname: Macnee
authors.forename: Stephen I
authors.initials: SI
authors.lastname: Rennard
authors.forename: David A
authors.initials: DA
authors.lastname: Lomas
authors.forename: Alvar
authors.initials: A
authors.lastname: Agusti
authors.forename: Bartolome R
authors.initials: BR
authors.lastname: Celli
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Black-Shinn
authors.forename: Greg L
authors.initials: GL
authors.lastname: Kinney
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Lutz
authors.forename: John E
authors.initials: JE
authors.lastname: Hokanson
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Silverman
authors.forename: George R
authors.initials: GR
authors.lastname: Washko
mesh_terms: D000368:Aged; D001823:Body Composition; D015992:Body Mass Index; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010369:Pectoralis Muscles / Q000000981:diagnostic imaging* / Q000473:pathology*; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D012907:Smoking; D014057:Tomography, X-Ray Computed