Quantitative Analysis of Adipose Depots by Using Chest CT and Associations with All-Cause Mortality in Chronic Obstructive Pulmonary Disease: Longitudinal Analysis from MESArthritis Ancillary Study

Abstract

Excessive adipose depots and sarcopenia are associated with poor prognosis and mortality in several chronic conditions including chronic obstructive pulmonary disease (COPD) (1,2). Obesity is associated with lower mortality in patients with COPD, referred to as the obesity paradox (3). Sarcopenia is the clinical syndrome of diminished muscle mass and strength and has an estimated prevalence of 22% in patients with COPD (2,4). In contradistinction to obesity, sarcopenia is associated with higher risks of mortality in COPD and impaired functional status (4,5).CT is the reference standard for the quantitative study of adipose depots (including the subcutaneous adipose tissue [SAT] and intermuscular adipose tissue [IMAT]).Background: Obesity and sarcopenia are associated with mortality in chronic obstructive pulmonary disease (COPD). Routine chest CT examinations may allow assessment of obesity and sarcopenia by soft-tissue markers for predicting risks of mortality.Purpose: To investigate associations between soft-tissue markers subcutaneous adipose tissue (SAT), intermuscular adipose tissue (IMAT), and pectoralis muscle (PM) index from chest CT with mortality in participants with COPD. Materials and Methods:In this secondary analysis of a prospectively enrolled cohort from the Multi-Ethnic Study of Atherosclerosis, participants with available chest CT in 2010-2012 were included. CT examinations were analyzed to determine SAT, IMAT (within PM), and PM areas. The spirometry evaluations were used to establish COPD diagnosis. Mortality data were extracted from the National Death Index (April 2010 to December 2017). The correlations of the soft-tissue markers with fat mass index were studied. The associations of these markers and risks of mortality in participants with COPD were assessed by using Cox proportional-hazard models adjusted for confounders.Results: Among 2994 participants who were included (mean age, 69 years  9 [standard deviation]; 1551 women), 265 had COPD (9%; mean age, 72 years  9; 162 men) and 49 participants with COPD (18%) died during follow-up. The SAT, IMAT, and PM areas had moderate-to-excellent reliabilities (intraclass correlation coefficient, 0.88-0.99). In the 2994 participants, the SAT ( = 0.80; 95% CI: 0.78, 0.81; P  .001) and IMAT indexes ( = 0.37; 95% CI: 0.34, 0.41; P  .001) were correlated with fat mass index. Those with COPD and higher SAT index had lower risks of mortality (hazard ratio, 0.2; 95% CI: 0.1, 0.4; P  .001, per doubling), whereas a higher IMAT index was associated with a higher risk of mortality (hazard ratio, 1.4; 95% CI: 1.0, 1.9; P = .04, per doubling). Conclusion:Soft-tissue markers were reliably obtained by using chest CT performed for lung assessment. In participants with chronic obstructive pulmonary disease, a high intermuscular adipose tissue index was associated with a higher risk of mortality than was a high subcutaneous adipose tissue index.

Adipose tissue biomarkers and type 2 diabetes incidence in normoglycemic participants in the MESArthritis Ancillary Study: A cohort study

“…Between April 2010 and January 2012 (fifth MESA exam), 3,137 participants in the MESA consented to participate in the MESA Lung Ancillary Study and underwent chest CT exams [ 19 ]. The MESArthritis Ancillary Study is an analysis of the available CT exams of 3,083 of these participants [ 20 ]. It is aimed to investigate the roles of CT-derived soft tissue and bone biomarkers associated with incidence and clinical outcomes of several cardiometabolic and cardiopulmonary diseases.…”

“…The non-contrast–enhanced chest CT exams (acquired at suspended full inspiration using 64-slice multidetector row CT scanners, Siemens Medical Solutions, Erlangen, Germany or GE Healthcare, Waukesha, Wisconsin, USA) were used to measure the IMAT and SAT areas as well as the pectoralis muscles (PMs) density [ 19 , 23 ]. The cross-sectional SAT area was measured as the area between the PM and skin surface in the slice just above the superior margin of the aortic arch [ 20 , 24 ]. Density of the SAT area was analyzed to estimate an individualized attenuation threshold for the IMAT (i.e., the extramyocellular lipid content) [ 20 , 25 ].…”

“…The cross-sectional SAT area was PLOS MEDICINE measured as the area between the PM and skin surface in the slice just above the superior margin of the aortic arch [20,24]. Density of the SAT area was analyzed to estimate an individualized attenuation threshold for the IMAT (i.e., the extramyocellular lipid content) [20,25]. The cross-sectional areas within the PM with attenuation below the estimated threshold were measured as the IMAT (S3 Fig) . The IMAT and SAT areas were corrected as IMAT and SAT indices (area by height squared, cm 2 /m 2 ) to account for the anthropometric variations.…”

Association of Quantified Costal Cartilage Calcification and Long-Term Cumulative Blood Glucose Exposure: The Multi-Ethnic Study of Atherosclerosis

“…The details of the MESA study design have been published previously ( 24 ). The MESArthritis study is an ancillary retrospective study of the MESA cohort to investigate the association of CT-derived soft tissue biomarkers with cardiovascular and metabolic risk factors and clinical outcomes ( 25 ). Previous reports of the MESArthritis study used the whole-chest CT scans of the MESA participants in exam 5; however, we have used the cardiac CT scans for our analysis ( 25 ).…”

“…The MESArthritis study is an ancillary retrospective study of the MESA cohort to investigate the association of CT-derived soft tissue biomarkers with cardiovascular and metabolic risk factors and clinical outcomes (25). Previous reports of the MESArthritis study used the whole-chest CT scans of the MESA participants in exam 5; however, we have used the cardiac CT scans for our analysis (25). Available non-contrast cardiac CT images from 3,305 participants acquired in the 5 th Institutional review boards at each of the six field centers recruited in the MESA study approved the study protocol.…”