Chest computed tomography-derived low fat-free mass index and mortality in COPD

Merry-Lynn N McDonald, Alejandro A Diaz, Erica Rutten, Sharon M Lutz, Rola Harmouche, Raul San Jose Estepar, Greg Kinney, John E Hokanson, Barbara A Gower, Emiel F M Wouters, Stephen I Rennard, Craig P Hersh, Richard Casaburi, Mark T Dransfield, Edwin K Silverman, George R Washko, Merry-Lynn N McDonald, Alejandro A Diaz, Erica Rutten, Sharon M Lutz, Rola Harmouche, Raul San Jose Estepar, Greg Kinney, John E Hokanson, Barbara A Gower, Emiel F M Wouters, Stephen I Rennard, Craig P Hersh, Richard Casaburi, Mark T Dransfield, Edwin K Silverman, George R Washko

Abstract

Low fat-free mass index (FFMI) is an independent risk factor for mortality in chronic obstructive pulmonary disease (COPD) not typically measured during routine care. In the present study, we aimed to derive fat-free mass from the pectoralis muscle area (FFMPMA) and assess whether low FFMIPMA is associated with all-cause mortality in COPD cases. We used data from two independent COPD cohorts, ECLIPSE and COPDGene.Two equal sized groups of COPD cases (n=759) from the ECLIPSE study were used to derive and validate an equation to calculate the FFMPMA measured using bioelectrical impedance from PMA. We then applied the equation in COPD cases (n=3121) from the COPDGene cohort, and assessed survival. Low FFMIPMA was defined, using the Schols classification (FFMI <16 in men, FFMI <15 in women) and the fifth percentile normative values of FFMI from the UK Biobank.The final regression model included PMA, weight, sex and height, and had an adjusted R2 of 0.92 with fat-free mass (FFM) as the outcome. In the test group, the correlation between FFMPMA and FFM remained high (Pearson correlation=0.97). In COPDGene, COPD cases with a low FFMIPMA had an increased risk of death (HR 1.6, p<0.001).We demonstrated COPD cases with a low FFMIPMA have an increased risk of death.

Conflict of interest statement

Conflict of interest: Disclosures can be found alongside this article at erj.ersjournals.com

Copyright ©ERS 2017.

Figures

Figure 1
Figure 1
A. Relationship between FFMPMA and FFM in test group comprised of 783 ECLIPSE COPD cases. B. Bland-Altman plot comparing FFMPMA and FFM in the test group. Abbreviations: FFMI – fat-free mass index, FFMIPMA – fat-free mass index derived from pectoralis muscle area, COPD – chronic obstructive pulmonary disease
Figure 2. Kaplan Meier Survival Stratified by…
Figure 2. Kaplan Meier Survival Stratified by Low FFMI
A. Low FFMIPMA defined using Schols cut-points of FFMIPMA <16 in men and FFMIPMA <15 in women[1] B. Low FFMIPMA defined by 5th percentile of normative FFMIPMA stratified by gender, age and BMI categories in the UK Biobank cohort[13]. Abbreviations: FFMI – fat-free mass index, FFMIPMA – fat-free mass index derived from pectoralis muscle area, COPD – chronic obstructive pulmonary disease

Source: PubMed

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