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

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 (FFM PMA ) and assess whether low FFMI PMA 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 FFM PMA measured using bioelectrical impedance from PMA. We then applied the equation in COPD cases (n=3121) from the COPDGene cohort, and assessed survival. Low FFMI PMA was defined, using the Schols classification (FFMI The final regression model included PMA, weight, sex and height, and had an adjusted R 2 of 0.92 with fat-free mass (FFM) as the outcome. In the test group, the correlation between FFM PMA and FFM remained high (Pearson correlation=0.97). In COPDGene, COPD cases with a low FFMI PMA had an increased risk of death (HR 1.6, p We demonstrated COPD cases with a low FFMI PMA have an increased risk of death.