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

Quantitative CT evaluation of extrapulmonary lesions in chronic obstructive pulmonary disease: a narrative review

Background and Objective

Chronic obstructive pulmonary disease (COPD) is a significant global health challenge characterized by persistent respiratory symptoms and airflow limitation. Recent advancements in computed tomography (CT) have enhanced our understanding of COPD, particularly in diagnosing extrapulmonary comorbidities. This review aims to summarize the current findings on extrapulmonary manifestations in COPD patients and the role of quantitative computed tomography (QCT) in evaluating these comorbidities.

Methods

A comprehensive literature search was conducted using PubMed and Web of Science databases, covering studies from January 1999 to May 2024. Keywords included "COPD", "chronic obstructive pulmonary disease", "muscle", "adipose tissue", "coronary artery calcification", "bone density", "extrapulmonary manifestations", and "Quantitative Computed Tomography". Inclusion criteria focused on studies involving COPD patients using QCT to identify extrapulmonary manifestations, published in peer-reviewed journals and available in English.

Key Content and Findings

The review highlights significant findings, such as the reduction in muscle mass and bone density and the increase in coronary artery calcification (CAC) in COPD patients, all closely associated with disease severity and prognosis. Key metrics evaluated include mid-thigh muscle cross-sectional area, pectoralis muscle area, erector spinae muscles, and bone density. Advanced CT analysis techniques, including artificial intelligence (AI) and machine learning, are emphasized as crucial for improving assessment accuracy and efficiency. Subcutaneous fat reduction and CAC are identified as critical indicators of mortality and disease progression.

Conclusions

Quantitative CT evaluation is vital for understanding and managing extrapulmonary lesions in COPD. Future research should focus on establishing suitable measurement tools and methods and defining critical thresholds for treatment efficacy. The integration of advanced CT techniques and interdisciplinary approaches is essential for enhancing diagnostic accuracy and developing personalized treatment strategies for COPD patients.

Nutritional Support of Chronic Obstructive Pulmonary Disease

Background: COPD is a heterogenous disease of the respiratory tract caused by diverse genetic factors along with environmental and lifestyle-related effects such as industrial dust inhalation and, most frequently, cigarette smoking. These factors lead to airflow obstruction and chronic respiratory symptoms. Additionally, the increased risk of infections exacerbates airway inflammation in COPD patients. As a consequence of the complex pathomechanisms and difficulty in treatment, COPD is among the leading causes of mortality both in the western countries and in the developing world. Results: The management of COPD is still a challenge for the clinicians; however, alternative interventions such as smoking cessation and lifestyle changes from a sedentary life to moderate physical activity with special attention to the diet may ameliorate patients' health. Here, we reviewed the effects of different dietary components and supplements on the conditions of COPD. Conclusions: COPD patients are continuously exposed to heavy metals, which are commonly present in cigarette smoke and polluted air. Meanwhile, they often experience significant nutrient deficiencies, which affect the detoxification of these toxic metals. This in turn can further disrupt nutritional balance by interfering with the absorption, metabolism, and utilization of essential micronutrients. Therefore, awareness and deliberate efforts should be made to check levels of micronutrients, with special attention to ensuring adequate levels of antioxidants, vitamin D, vitamin K2, magnesium, and iron, as these may be particularly important in reducing the risk of COPD development and limiting disease severity.

Effect of Common Medications on Longitudinal Pectoralis Muscle Area in Smokers

Background

Cigarette smoke contributes to skeletal muscle wasting. While exercise and nutritional therapies are effective in improving skeletal muscle quantity and quality, the effect of medications on longitudinal muscle loss is unclear. We investigated whether long-term use of common medications affects longitudinal skeletal muscle changes in current and former smokers.

Methods

Using quantitative computed tomography imaging, we measured the 5-year changes in pectoralis muscle area (delta-PMA) and pectoralis muscle density (delta-PMD) of 4191 participants in the COPD Genetic Epidemiology (COPDGene®) study. We tested whether specific medications were associated with delta-PMA and/or delta-PMD using regression analyses. Propensity score matching (PSM) analysis was performed to determine the effect of the medications on longitudinal changes on delta-PMA.

Results

Over the study period, the median delta-PMA for the entire population showed a decrease of 2.23cm2 (interquartile range: -6.52, 1.54). Regression analyses demonstrated statin use was associated with less loss of PMA, whereas, aspirin use was associated with a greater loss of PMA. Specifically, in the PSM-adjusted analysis, statin use was associated with attenuated loss of PMA (median; -1.5 versus -2.5cm2, p=0.017), while aspirin use was associated with increased loss of PMA (median; -2.5 versus -1.9cm2, p=0.040).

Conclusion

In current and former smokers, statin use was associated with reduced pectoralis muscle wasting, while aspirin use was associated with increased muscle loss. Additional research is needed to verify these findings. (Clinicaltrials.gov identifier NCT00608764).

Nocturnal Hypoxemia Is Associated with Sarcopenia in Patients with Chronic Obstructive Pulmonary Disease

Rationale: Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. Our previous studies have identified that nocturnal hypoxemia causes skeletal muscle loss (i.e., sarcopenia) in in vitro models of COPD. Objectives: We aimed to extend our preclinical mechanistic findings by analyzing a large sleep registry to determine whether nocturnal hypoxemia is associated with sarcopenia in patients with COPD. Methods: Sleep studies from patients with COPD (n = 479) and control subjects without COPD (n = 275) were analyzed. Patients with obstructive sleep apnea, as defined by apnea-hypopnea index ⩾ 5, were excluded. Pectoralis muscle cross-sectional area (PMcsa) was quantified using computed tomography scans performed within 1 year of the sleep study. We defined sarcopenia as less than the lowest 20% residuals for PMcsa of control subjects, which was adjusted for age and body mass index (BMI) and stratified by sex. Youden's optimal cut-point criteria were used to predict sarcopenia based on mean oxygen saturation during sleep. Additional measures of nocturnal hypoxemia were analyzed. The pectoralis muscle index (PMI) was defined as PMcsa normalized to BMI. Results: On average, males with COPD had a 16.6% lower PMI than control males (1.41 ± 0.44 vs. 1.69 ± 0.56 cm2/BMI; P < 0.001), whereas females with COPD had a 9.4% lower PMI than control females (0.96 ± 0.27 vs. 1.06 ± 0.33 cm2/BMI; P < 0.001). Males with COPD with nocturnal hypoxemia had a 9.5% decrease in PMI versus COPD with normal O2 (1.33 ± 0.39 vs. 1.47 ± 0.46 cm2/BMI; P < 0.05) and a 23.6% decrease compared with control subjects (1.33 ± 0.39 vs. 1.74 ± 0.56 cm2/BMI; P < 0.001). Females with COPD with nocturnal hypoxemia had an 11.2% decrease versus COPD with normal O2 (0.87 ± 0.26 vs. 0.98 ± 0.28 cm2/BMI; P < 0.05) and a 17.9% decrease compared with control subjects (0.87 ± 0.26 vs. 1.06 ± 0.33 cm2/BMI; P < 0.001). These findings were largely replicated using multiple measures of nocturnal hypoxemia. Conclusions: We defined sarcopenia in the pectoralis muscle using residuals that take into account age, BMI, and sex. We found that patients with COPD have a lower PMI than patients without COPD and that nocturnal hypoxemia was associated with an additional decrease in the PMI of patients with COPD. Additional prospective analyses are needed to determine a protective threshold of oxygen saturation to prevent or reverse sarcopenia due to nocturnal hypoxemia in COPD.

Influence of weight-adjusted contrast enhancement on computed tomography-derived skeletal muscle measures: a retrospective proof-of-concept comparative study between Danish females and males

BACKGROUND

Computed tomography (CT) has an underutilized potential for evaluating body composition in clinical settings. Often conducted with intravenous contrast (IVC), CT scans yield unused body composition data due to unclear effects on skeletal muscle area (SMA), skeletal muscle index (SMI), and muscle density (SMD).

OBJECTIVES

This study investigates whether weight-adjusted IVC influences SMA, SMI, and SMD differently in females and males compared with noncontrast abdominal CT. In addition, the study explores associations between contrast and noncontrast-assessed SMA, SMI, SMD, and demographic factors.

METHODS

A comparative observational retrospective study was conducted on Danish patients who underwent consecutive 4-phased contrast-enhanced abdominal CT scans (noncontrast, arterial, venous, and late venous phases). Muscle measures were evaluated using validated semiautomated threshold-based software by 3 independent raters.

RESULTS

The study included 72 patients (51 males and 21 females) with a mean age of 59 (55 and 62) y. Weight-adjusted IVC increased SMA by ≤3.28 cm2 (95% confidence interval [CI]: 2.58, 3.98) corresponding to 2.4% (1.8, 2.9) in the late venous phase compared with noncontrast CT. Analysis between sexes showed no difference in the effects of IVC on SMA and SMI between females and males. However, females exhibited a higher increase in SMD during the venous by a mean of 1.7 HU (0.9; 2.5) and late venous phases with a mean HU of 1.80 (1.0; 2.6) compared with males. Multivariate regression analysis indicated an association between the differences in SMD and sex during venous (-1.38, 95% CI: -2.48, -0.48) and late venous phases (-1.23, 95% CI: -2.27, -0.19).

CONCLUSIONS

Weight-adjusted IVC leads to increased SMA, SMI, and SMD. Although SMA and SMI differences were consistent across the sexes, females exhibited a significantly higher SMD increase than males in the venous and late venous phases. Further investigations are necessary to determine the applicability of SMD as a muscle quality proxy in IVC CT scans.

Proteomics and machine learning in the prediction and explanation of low pectoralis muscle area

Low muscle mass is associated with numerous adverse outcomes independent of other associated comorbid diseases. We aimed to predict and understand an individual's risk for developing low muscle mass using proteomics and machine learning. We identified eight biomarkers associated with low pectoralis muscle area (PMA). We built three random forest classification models that used either clinical measures, feature selected biomarkers, or both to predict development of low PMA. The area under the receiver operating characteristic curve for each model was: clinical-only = 0.646, biomarker-only = 0.740, and combined = 0.744. We displayed the heterogenetic nature of an individual's risk for developing low PMA and identified two distinct subtypes of participants who developed low PMA. While additional validation is required, our methods for identifying and understanding individual and group risk for low muscle mass could be used to enable developments in the personalized prevention of low muscle mass.

The evolution and impact of sarcopenia in severe aplastic anaemia survivors following allogeneic haematopoietic cell transplantation

BACKGROUND

Sarcopenia is a potential risk factor for adverse outcomes in haematopoietic cell transplantation (HSCT) recipients. We aimed to explore longitudinal body changes in muscle and adipose mass and their prognostic value in allogeneic HSCT-treated severe aplastic anaemia (SAA) patients.

METHODS

We retrospectively analysed consecutive SAA patients who underwent allogeneic HSCT between January 2017 and March 2022. Measurements of pectoral muscle and corresponding subcutaneous fat mass were obtained via chest computed tomography at baseline and at 1 month, 3 months, 6 months, and 12 months following HSCT. Sarcopenia was defined as pectoral muscle index (PMI) lower than the sex-specific median at baseline. Changes in body composition over time were evaluated by generalized estimating equations. Cox regression models were used to investigate prognostic factors affecting overall survival (OS) and failure-free survival (FFS). A nomogram was constructed from the Cox regression model for OS.

RESULTS

We included 298 adult SAA patients (including 129 females and 169 males) with a median age of 31 years [interquartile range (IQR), 24-39 years] at baseline. Sarcopenia was present in 148 (148/298, 50%) patients at baseline, 218 (218/285, 76%) patients post-1 month, 209 (209/262, 80%) patients post-3 month, 169 (169/218, 78%) patients post-6 month, and 129 (129/181, 71%) patients post-12 month. A significant decrease in pectoral muscle mass was observed in SAA patients from the time of transplant to 1 year after HSCT, and the greatest reduction occurred in post 1-3 months (P < 0.001). The sarcopenia group exhibited significantly lower 5-year OS (90.6% vs. 100%, log-rank P = 0.039) and 5-year FFS (89.2% vs. 100%, log-rank P = 0.021) than the nonsarcopenia group at baseline. Sarcopenia at baseline (hazard ratio, HR, 6.344; 95% confidence interval, CI: 1.570-25.538; P = 0.01; and HR, 3.275; 95% CI: 1.159-9.252; P = 0.025, respectively) and the delta value of the PMI at 6 months post-transplantation (ΔPMI6) (HR, 0.531; 95% CI: 0.374-0.756; P < 0.001; and HR, 0.666; 95% CI: 0.505-0.879; P = 0.004, respectively) were demonstrated to be independent prognostic factors for OS and FFS in SAA patients undergoing HSCT, and were used to construct the nomogram. The C-index of the nomogram was 0.75, and the calibration plot showed good agreement between the predictions made by the nomogram and actual observations.

CONCLUSIONS

Sarcopenia persists in SAA patients from the time of transplant to the 1-year follow-up after HSCT. Both sarcopenia at baseline and at 6 months following HSCT are associated with poor clinical outcomes, especially in patients with persistent muscle mass loss up to 6 months after transplantation.

Malnutrition and pectoralis muscle index in medical intensive care unit patients: A matched cohort study

BACKGROUND

Muscle assessment is an important component of nutrition assessment. The Global Leadership Initiative on Malnutrition (GLIM) consortium recently underscored the need for more objective muscle assessment methods in clinical settings. Various assessment techniques are available; however, many have limitations in clinical populations. Computed tomography (CT) scans, obtained for diagnostic reasons, could serve multiple purposes, including muscle measurement for nutrition assessment. Although CT scans of the chest are commonly performed clinically, there is little research surrounding the utility of pectoralis muscle measurements in nutrition assessment. The primary aim was to determine whether CT-derived measures of pectoralis major cross-sectional area (PMA) and quality (defined as mean pectoralis major Hounsfield units [PMHU]) could be used to identify malnutrition in patients who are mechanically ventilated in an intensive care unit (ICU). A secondary aim was to evaluate the relationship between these measures and clinical outcomes in this population.

METHODS

A retrospective analysis was conducted on 33 pairs of age- and sex-matched adult patients who are being mechanically ventilated in the ICU. Patients were grouped by nutrition status. Analyses were performed to determine differences in PMA and mean PMHU between groups. Associations between muscle and clinical outcomes were also investigated.

RESULTS

Compared with nonmalnourished controls, malnourished patients had a significantly lower PMA (P = 0.001) and pectoralis major (PM) index (PMA/height in m2; P = 0.001). No associations were drawn between PM measures and clinical outcomes.

CONCLUSION

These findings regarding CT PM measures lay the groundwork for actualizing the GLIM call to action to validate quantitative, objective muscle assessment methods in clinical settings.

Association between computed tomography-quantified respiratory muscles and chronic obstructive pulmonary disease: a retrospective study

BACKGROUND

This study examined the association between chest muscles and chronic obstructive pulmonary disease (COPD) and the relationship between chest muscle areas and acute exacerbations of COPD (AECOPD).

METHODS

There were 168 subjects in the non-COPD group and 101 patients in the COPD group. The respiratory and accessory respiratory muscle areas were obtained using 3D Slicer software to analysis the imaging of  computed tomography (CT). Univariate and multivariate Poisson regressions were used to analyze the number of AECOPD cases during the preceding year. The cutoff value was obtained using a receiver operating characteristic (ROC) curve.

RESULTS

We scanned 6342 subjects records, 269 of which were included in this study. We then measured the following muscle areas (non-COPD group vs. COPD group): pectoralis major (19.06 ± 5.36 cm2 vs. 13.25 ± 3.71 cm2, P < 0.001), pectoralis minor (6.81 ± 2.03 cm2 vs. 5.95 ± 1.81 cm2, P = 0.001), diaphragmatic dome (1.39 ± 0.97 cm2 vs. 0.85 ± 0.72 cm2, P = 0.011), musculus serratus anterior (28.03 ± 14.95 cm2 vs.16.76 ± 12.69 cm2, P < 0.001), intercostal muscle (12.36 ± 6.64 cm2 vs. 7.15 ± 5.6 cm2, P < 0.001), pectoralis subcutaneous fat (25.91 ± 13.23 cm2 vs. 18.79 ± 10.81 cm2, P < 0.001), paravertebral muscle (14.8 ± 4.35 cm2 vs. 13.33 ± 4.27 cm2, P = 0.007), and paravertebral subcutaneous fat (12.57 ± 5.09 cm2 vs. 10.14 ± 6.94 cm2, P = 0.001). The areas under the ROC curve for the pectoralis major, intercostal, and the musculus serratus anterior muscle areas were 81.56%, 73.28%, and 71.56%, respectively. Pectoralis major area was negatively associated with the number of AECOPD during the preceding year after adjustment (relative risk, 0.936; 95% confidence interval, 0.879-0.996; P = 0.037).

CONCLUSION

The pectoralis major muscle area was negative associated with COPD. Moreover, there was a negative correlation between the number of AECOPD during the preceding year and the pectoralis major area.

Pectoralis Muscle Area as a Predictor of Mortality in Patients Hospitalized with Bronchiectasis Exacerbation

INTRODUCTION

Data on factors related to mortality in patients with bronchiectasis exacerbation are insufficient. Computed tomography (CT) can measure the pectoralis muscle area (PMA) and is a useful tool to diagnose sarcopenia. This study aimed to evaluate whether PMA can predict mortality in patients with bronchiectasis exacerbation.

METHODS

Patients hospitalized due to bronchiectasis exacerbation at a single center were retrospectively divided into survivors and non-survivors based on 1-year mortality. Thereafter, a comparison of the clinical and radiologic characteristics was conducted between the two groups.

RESULTS

A total of 66 (14%) patients died at 1 year. In the multivariate analysis, age, BMI <18.4 kg/m2, sex-specific PMA quartile, ≥3 exacerbations in the previous year, serum albumin <3.5 g/dL, cystic bronchiectasis, tuberculosis-destroyed lung, and diabetes mellitus were independent predictors for the 1-year mortality in patients hospitalized with bronchiectasis exacerbation. A lower PMA was associated with a lower overall survival rate in the survival analysis according to sex-specific quartiles of PMA. PMA had the highest area under the curve during assessment of prognostic performance in predicting the 1-year mortality. The lowest sex-specific PMA quartile group exhibited higher disease severity than the highest quartile group.

CONCLUSIONS

CT-derived PMA was an independent predictor of 1-year mortality in patients hospitalized with bronchiectasis exacerbation. Patients with lower PMA exhibited higher disease severity. These findings suggest that PMA might be a useful marker for providing additional information regarding prognosis of patients with bronchiectasis exacerbation.

Association between the Static and Dynamic Lung Function and CT-Derived Thoracic Skeletal Muscle Measurements-A Retrospective Analysis of a 12-Month Observational Follow-Up Pilot Study

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) with low skeletal muscle mass and severe airway obstruction have higher mortality risks. However, the relationship between dynamic/static lung function (LF) and thoracic skeletal muscle measurements (SMM) remains unclear. This study explored patient characteristics (weight, BMI, exacerbations, dynamic/static LF, sex differences in LF and SMM, and the link between LF and SMM changes.

METHODS

A retrospective analysis of a 12-month prospective follow-up study patients with stable COPD undergoing standardized treatment, covering mild to severe stages, was conducted. The baseline and follow-up assessments included computed tomography and body plethysmography.

RESULTS

This study included 35 patients (17 females and 18 males). This study revealed that females had more stable LF but tended to have greater declines in SMM areas and indices than males (-5.4% vs. -1.9%, respectively), despite the fact that females were younger and had higher LF and less exacerbation than males. A multivariate linear regression showed a negative association between the inspiratory capacity/total lung capacity ratio (IC/TLC) and muscle fat area.

CONCLUSIONS

The findings suggest distinct LF and BC progression patterns between male and female patients with COPD. A low IC/TLC ratio may predict increased muscle fat. Further studies are necessary to understand these relationships better.

Proteomics and Machine Learning in the Prediction and Explanation of Low Pectoralis Muscle Area

Low muscle mass is associated with numerous adverse outcomes independent of other associated comorbid diseases. We aimed to predict and understand an individual's risk for developing low muscle mass using proteomics and machine learning. We identified 8 biomarkers associated with low pectoralis muscle area (PMA). We built 3 random forest classification models that used either clinical measures, feature selected biomarkers, or both to predict development of low PMA. The area under the receiver operating characteristic curve for each model was: clinical-only = 0.646, biomarker-only = 0.740, and combined = 0.744. We displayed the heterogenetic nature of an individual's risk for developing low PMA and identified 2 distinct subtypes of participants who developed low PMA. While additional validation is required, our methods for identifying and understanding individual and group risk for low muscle mass could be used to enable developments in the personalized prevention of low muscle mass.

Integrated assessment of computed tomography density in pectoralis and erector spinae muscles as a prognostic biomarker for coronavirus disease 2019

BACKGROUND ＆ AIMS: Muscle quantification using chest computed tomography (CT) is a useful prognostic biomarker for coronavirus disease 2019 (COVID-19). However, no studies have evaluated the clinical course through comprehensive assessment of the pectoralis and erector spinae muscles. Therefore, we compared the impact of the areas and densities of these muscles on COVID-19 infection outcome.

METHODS

This multicenter retrospective cohort study was conducted by the COVID-19 Task Force. A total of 1410 patients with COVID-19 were included, and data on the area and density of the pectoralis and erector spinae muscles on chest CT were collected. The impact of each muscle parameter on the clinical outcome of COVID-19 was stratified according to sex. The primary outcome was the percentage of patients with severe disease, including those requiring oxygen supplementation and those who died. Additionally, 167 patients were followed up for changes in muscle parameters at three months and for the clinical characteristics in case of reduced CT density.

RESULTS

For both muscles, low density rather than muscle area was associated with COVID-19 severity. Regardless of sex, lower erector spinae muscle density was associated with more severe disease than pectoralis muscle density. The muscles were divided into two groups using the receiver operating characteristic curve of CT density, and the population was classified into four (Group A: high CT density for both muscles, Group B: low CT density for pectoralis and high for erector spinae muscle. Group C: high CT density for pectoralis and low for erector spinae muscle, Group D: low CT density for both muscles). In univariate analysis, Group D patients exhibited worse outcomes than Group A (OR: 2.96, 95% CI: 2.03-4.34 in men; OR: 3.02, 95% CI: 2.66-10.4 in women). Multivariate analysis revealed that men in Group D had a significantly more severe prognosis than those in Group A (OR: 1.82, 95% CI: 1.16-2.87). Moreover, Group D patients tended to have the highest incidence of other complications due to secondary infections and acute kidney injury during the clinical course. Longitudinal analysis of both muscle densities over three months revealed that patients with decreased muscle density over time were more likely to have severe cases than those who did not.

CONCLUSIONS

Muscle density, rather than muscle area, predicts the clinical outcomes of COVID-19. Integrated assessment of pectoralis and erector spinae muscle densities demonstrated higher accuracy in predicting the clinical course of COVID-19 than individual assessments.

Association of musculoskeletal involvement with lung function and mortality in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive disease associated with high mortality. Low muscle mass, frailty and sarcopenia lead to functional impairment that negatively impact quality of life and survival but are not used in clinical practice. We aimed to determine the association of Fat-free mass index (FFMI) and frailty with lung function, exercise tolerance and survival in patients with IPF. In this study, 70 patients with IPF underwent assessment of body composition, lung function, 6-min walk distance (6MWD) testing, hand grip strength, quality of life (QoL) assessment by St. George's Respiratory questionnaire (SGRQ) and frailty assessment using the SHARE-FI tool. FFMI was calculated using pectoralis muscle cross-sectional area (PM-CSA) on CT chest images and the lowest quartile defined reduced muscle mass. Sarcopenia was defined as low FFMI and handgrip strength. Regression analyses were conducted to determine predictive value of frailty, low FFMI and sarcopenia on clinical outcomes. The Cox proportional hazards model was used to analyze the impact of FFMI and frailty score on survival. The mean age was 70 years with moderate impairment in lung function (mean ppFVC 68.5%, ppDLCO 45.6%). Baseline forced vital capacity (p < 0.001), diffusion capacity of lung for carbon monoxide (p =  < 0.01), 6WMD (p < 0.05) were significantly lower in frail patients compared to non-frail patients. BMI was found to closely correlate with FFMI (r = 0.79, p < 0.001), but not with frailty score (r = - 0.2, p = 0.07). Frailty was a significant predictor of FVC, DLCO, 6MWD, SGRQ scores when adjusted for age and gender. Muscle mass and sarcopenia were significant predictors of FVC, DLCO, but not 6MWD or QoL scores. Multivariate cox-proportional hazards ratio model adjusting for age and gender showed that frailty was significantly associated with increased mortality (HR = 2.6, 95% CI 1.1-6.1). Low FFMI (HR = 1.3, 95% CI 0.6-2.8), and sarcopenia (HR = 2.1, 95% CI 0.8-5.3), though associated with a trend to increased mortality, were not statistically significant. Frailty is associated with lower lung function and higher mortality in patients with IPF. Longitudinal evaluations are necessary to further determine the associations between low FFMI, sarcopenia and frailty with outcomes in IPF.

A fully automated pipeline for the extraction of pectoralis muscle area from chest computed tomography scans

Background

Computed tomography (CT)-derived pectoralis muscle area (PMA) measurements are prognostic in people with or at-risk of COPD, but fully automated PMA extraction has yet to be developed. Our objective was to develop and validate a PMA extraction pipeline that can automatically: 1) identify the aortic arch slice; and 2) perform pectoralis segmentation at that slice.

Methods

CT images from the Canadian Cohort of Obstructive Lung Disease (CanCOLD) study were used for pipeline development. Aorta atlases were used to automatically identify the slice containing the aortic arch by group-based registration. A deep learning model was trained to segment the PMA. The pipeline was evaluated in comparison to manual segmentation. An external dataset was used to evaluate generalisability. Model performance was assessed using the Dice-Sorensen coefficient (DSC) and PMA error.

Results

In total 90 participants were used for training (age 67.0±9.9 years; forced expiratory volume in 1 s (FEV1) 93±21% predicted; FEV1/forced vital capacity (FVC) 0.69±0.10; 47 men), and 32 for external testing (age 68.6±7.4 years; FEV1 65±17% predicted; FEV1/FVC 0.50±0.09; 16 men). Compared with manual segmentation, the deep learning model achieved a DSC of 0.94±0.02, 0.94±0.01 and 0.90±0.04 on the true aortic arch slice in the train, validation and external test sets, respectively. Automated aortic arch slice detection obtained distance errors of 1.2±1.3 mm and 1.6±1.5 mm on the train and test data, respectively. Fully automated PMA measurements were not different from manual segmentation (p>0.05). PMA measurements were different between people with and without COPD (p=0.01) and correlated with FEV1 % predicted (p<0.05).

Conclusion

A fully automated CT PMA extraction pipeline was developed and validated for use in research and clinical practice.

Prognostic impact of the cross-sectional area of the erector spinae muscle in patients with pleuroparenchymal fibroelastosis

Pleuroparenchymal fibroelastosis (PPFE) progresses slowly but sometimes relatively quickly, leading to decreased activities of daily living (ADL) and muscle weakness. Skeletal muscle atrophy and muscle weakness in chronic obstructive pulmonary disease (COPD) patients may be caused by cachexia and are associated with reduced ADLs and increased risk of death. However, the association between skeletal muscle mass and the prognosis of PPFE patients remains unknown. We retrospectively analysed the clinical significance of the cross-sectional area of the erector spinae muscle (ESMCSA), a skeletal muscle index, and predictors of mortality within 3 years in PPFE 51 patients, idiopathic pulmonary fibrosis (IPF) 52 patients and COPD 62 patients. PPFE patients had significantly lower ESMCSA than IPF or COPD patients, and lower ESMCSA (< 22.57 cm2) was associated with prognosis within 3 years (log-rank test; p = 0.006), whereas lower body mass index (BMI) showed no association. Multivariate analysis showed that ESMCSA was an independent predictor of mortality within 3 years in PPFE patients (hazard ratio, 0.854; 95% confidence interval: 0.737-0.990, p = 0.036). These results suggest the importance of monitoring ESMCSA in PPFE patients and that assessing ESMCSA in PPFE patients could be a more useful prognostic indicator than BMI.

Incident low muscle mass is associated with greater lung disease and lower circulating leptin in a tobacco-exposed longitudinal cohort

BACKGROUND

Muscle loss is prevalent in chronic obstructive pulmonary disease (COPD). Prior studies evaluating musculoskeletal dysfunction in COPD have focused on individuals with baseline low muscle mass. Currently, there is limited data evaluating clinical characteristics and outcomes associated with progression to incident low muscle mass in a tobacco-exposed cohort of individuals with baseline normal muscle mass.

METHODS

We evaluated 246 participants from a single-center longitudinal tobacco-exposed cohort with serial spirometry, thoracic imaging, dual energy x-ray absorptiometry (DXA) measurements, walk testing, and plasma adipokine measurements. DXA-derived fat free mass index (FFMI) and appendicular skeletal mass index (ASMI) were used as surrogates for muscle mass. Participants with incident low muscle mass (LM) at follow-up were characterized by FFMI < 18.4 kg/m2 in males and < 15.4 kg/m2 in females and/or ASMI < 7.25 kg/m2 in males and < 5.67 kg/m2 in females.

RESULTS

Twenty-five (10%) participants progressed to incident low muscle mass at follow-up. At baseline, the LM subgroup had greater active smoking prevalence (60% v. 38%, p = 0.04), lower FFMI (17.8 ± 1.7 kg/m2 v. 19.7 ± 2.9 kg/m2, p = 0.002), lower ASMI (7.3 ± 0.9 kg/m2 v. 8.2 ± 1.2 kg/m2, p = 0.0003), and lower plasma leptin (14.9 ± 10.1 ng/mL v. 24.0 ± 20.9 ng/mL, p = 0.04). At follow-up, the LM subgroup had higher COPD prevalence (68% v. 43%, p = 0.02), lower FEV1/FVC (0.63 ± 0.12 v. 0.69 ± 0.12, p = 0.02), lower %DLco (66.5 ± 15.9% v. 73.9 ± 16.8%, p = 0.03), and higher annual rate of FFMI decline (-0.17 kg/m2/year v. -0.04 kg/m2/year, p = 0.006). There were no differences in age, gender distribution, pack years smoking history, or walk distance.

CONCLUSIONS

We identified a subgroup of tobacco-exposed individuals with normal baseline muscle mass who progressed to incident DXA-derived low muscle mass. This subgroup demonstrated synchronous lung disease and persistently low circulating leptin levels. Our study suggests the importance of assessing for muscle loss in conjunction with lung function decline when evaluating individuals with tobacco exposure.

CT-Derived Deep Learning-Based Quantification of Body Composition Associated with Disease Severity in Chronic Obstructive Pulmonary Disease

Purpose

Our study aimed to evaluate the association between automated quantified body composition on CT and pulmonary function or quantitative lung features in patients with chronic obstructive pulmonary disease (COPD).

Materials and Methods

A total of 290 patients with COPD were enrolled in this study. The volume of muscle and subcutaneous fat, area of muscle and subcutaneous fat at T12, and bone attenuation at T12 were obtained from chest CT using a deep learning-based body segmentation algorithm. Parametric response mapping-derived emphysema (PRMemph), PRM-derived functional small airway disease (PRMfSAD), and airway wall thickness (AWT)-Pi10 were quantitatively assessed. The association between body composition and outcomes was evaluated using Pearson's correlation analysis.

Results

The volume and area of muscle and subcutaneous fat were negatively associated with PRMemph and PRMfSAD (p < 0.05). Bone density at T12 was negatively associated with PRMemph (r = -0.1828, p = 0.002). The volume and area of subcutaneous fat and bone density at T12 were positively correlated with AWT-Pi10 (r = 0.1287, p = 0.030; r = 0.1668, p = 0.005; r = 0.1279, p = 0.031). However, muscle volume was negatively correlated with the AWT-Pi10 (r = -0.1966, p = 0.001). Muscle volume was significantly associated with pulmonary function (p < 0.001).

Conclusion

Body composition, automatically assessed using chest CT, is associated with the phenotype and severity of COPD.

Predictors of longitudinal changes in body weight, muscle and fat in patients with and ever-smokers at risk of COPD

BACKGROUND AND OBJECTIVE

Weight and muscle loss are predictors of poor outcomes in chronic obstructive pulmonary disease. However, to our knowledge, no study has investigated the predictors of longitudinal weight loss or its composition from functional and morphological perspectives.

METHODS

This longitudinal observational study with a median follow-up period of 5 years (range: 3.0-5.8 years) included patients with COPD and ever-smokers at risk of COPD. Using chest computed tomography (CT) images, airway and emphysematous lesions were assessed as the square root of the wall area of a hypothetical airway with an internal perimeter of 10 mm (√Aaw at Pi10) and the percentage of low attenuation volume (LAV%). Muscle mass was estimated using cross-sectional areas (CSAs) of the pectoralis and erector spinae muscles, and fat mass was estimated using the subcutaneous fat thickness at the level of the 8th rib measured using chest CT images. Statistical analyses were performed using the linear mixed-effects models.

RESULTS

In total, 114 patients were enrolled. Their body mass index remained stable during the study period while body weight and muscle CSA decreased over time and the subcutaneous fat thickness increased. Reduced forced expiratory volume in 1 s and peak expiratory flow (PEF) at baseline predicted the future decline in muscle CSA.

CONCLUSION

Severe airflow limitation predicted future muscle wasting in patients with COPD and ever-smokers at risk of COPD. Airflow limitation with a PEF slightly below 90% of the predicted value may require intervention to prevent future muscle loss.

Association between appendicular lean mass and chronic obstructive pulmonary disease: epidemiological cross-sectional study and bidirectional Mendelian randomization analysis

Background

The association of BMI with COPD, and sarcopenia in COPD have been both confirmed by several studies, but research on the relationship and causality of body lean mass and the risk of chronic obstructive pulmonary disease (COPD) remains to be discovered. The purpose of this study was to explore the association between lean mass and COPD risk as well as to further examine the causal relationship in the findings.

Methods

Three thousand four hundred fifty-nine participants from NHANES 2013-2018 were included in the epidemiological cross-sectional study to assess the association between relative lean mass and COPD by restricted spline analysis (RCS) and weighted multiple logistic regression. Furthermore, to verify the causality between lean mass and COPD, a two-sample Mendelian randomization (MR) with inverse variance weighting (IVW) method was used to analyze GWAS data from European ancestry. Genetic data from the United Kindom Biobank for appendicular lean mass (450,243 cases) and lung function (FEV₁/FVC) (400,102 cases) together with the FinnGen platform for COPD (6,915 cases and 186,723 controls) were used for MR.

Results

Weighted multiple logistic regression showed a significant correlation between relative appendicular lean mass and COPD after adjusting for confounders (OR = 0.985, 95% CI: 0.975-0.995). Compared to the lower mass (155.3-254.7) g/kg, the high mass (317.0-408.5) g/kg of appendicular lean apparently decreases the risk of COPD (OR = 0.214, 95% CI: 0.060-0.767). Besides, in the analysis of MR, there was a forward causality between appendicular lean mass and COPD (IVW: OR = 0.803; 95%CI: 0.680-0.949; p = 0.01), with a weak trend of causality to lung function.

Conclusion

Our study not only found an inverse association between appendicular lean mass and COPD but also supported a unidirectional causality. This provided possible evidence for further identification of people at risk for COPD and prevention of COPD based on limb muscle exercise and nutritional supplementation to maintain skeletal muscle mass.

Association between thoracic and third lumbar CT-derived muscle mass and density in Caucasian patients without chronic disease: a proof-of-concept study

BACKGROUND

Computed tomography (CT) is increasingly used in the clinical workup, and existing scan contains unused body composition data, potentially useful in a clinical setting. However, there is no healthy reference for contrast-enhanced thoracic CT-derived muscle measures. Therefore, we aimed at investigating whether there is a correlation between each of the thoracic and third lumbar vertebra level (L3) skeletal muscle area (SMA), skeletal muscle index (SMI), and skeletal muscle density (SMD) at contrast-enhanced CT in patients without chronic disease.

METHODS

A proof-of-concept retrospective observational study was based on Caucasian patients without chronic disease, who received CT for trauma between 2012 and 2014. Muscle measures were assessed using a semiautomated threshold-based software by two raters independently. Pearson's correlation between each thoracic level and third lumbar and intraclass correlation between two raters and test-retest with SMA as proxy parameters were used.

RESULTS

Twenty-one patients (11 males, 10 females; median age 29 years) were included. The second thoracic vertebra (T2) had the highest median of cumulated SMA (males 314.7 cm², females 118.5 cm²) and SMI (97.8 cm²/m² and 70.4 cm²/m², respectively). The strongest SMA correlation was observed between T5 and L3 (r = 0.970), the SMI between T11 and L3 (r = 0.938), and the SMD between the T10 and L3 (r = 0.890).

CONCLUSIONS

This study suggests that any of the thoracic levels can be valid to assess skeletal muscle mass. However, the T5 may be most favourable for measuring SMA, the T11 for SMI, and T10 for SMD when using contrast-enhanced thoracic CT.

RELEVANCE STATEMENT

In COPD patients, a CT-derived thoracic muscle mass assessment may help identify who would benefit from focused pulmonary rehabilitation: thoracic contrast-enhanced CT conducted as part of the standard clinical workup can be used for this evaluation.

KEY POINTS

• Any thoracic level can be used to assess thoracic muscle mass. • Thoracic level 5 is strongly associated with the 3rd lumbar muscle area. • A strong correlation between the thoracic level 11 and the 3rd lumbar muscle index. • Thoracic level 10 is strongly associated with the 3rd lumbar muscle density.

Gene polymorphisms associated with heterogeneity and senescence characteristics of sarcopenia in chronic obstructive pulmonary disease

BACKGROUND

Sarcopenia, or loss of skeletal muscle mass and decreased contractile strength, contributes to morbidity and mortality in patients with chronic obstructive pulmonary disease (COPD). The severity of sarcopenia in COPD is variable, and there are limited data to explain phenotype heterogeneity. Others have shown that COPD patients with sarcopenia have several hallmarks of cellular senescence, a potential mechanism of primary (age-related) sarcopenia. We tested if genetic contributors explain the variability in sarcopenic phenotype and accelerated senescence in COPD.

METHODS

To identify gene variants [single nucleotide polymorphisms (SNPs)] associated with sarcopenia in COPD, we performed a genome-wide association study (GWAS) of fat free mass index (FFMI) in 32 426 non-Hispanic White (NHW) UK Biobank participants with COPD. Several SNPs within the fat mass and obesity-associated (FTO) gene were associated with sarcopenia that were validated in an independent COPDGene cohort (n = 3656). Leucocyte telomere length quantified in the UK Biobank cohort was used as a marker of senescence. Experimental validation was done by genetic depletion of FTO in murine skeletal myotubes exposed to prolonged intermittent hypoxia or chronic hypoxia because hypoxia contributes to sarcopenia in COPD. Molecular biomarkers for senescence were also quantified with FTO depletion in murine myotubes.

RESULTS

Multiple SNPs located in the FTO gene were associated with sarcopenia in addition to novel SNPs both within and in proximity to the gene AC090771.2, which transcribes long non-coding RNA (lncRNA). To replicate our findings, we performed a GWAS of FFMI in NHW subjects from COPDGene. The SNP most significantly associated with FFMI was on chromosome (chr) 16, rs1558902A > T in the FTO gene (β = 0.151, SE = 0.021, P = 1.40 × 10-12 for UK Biobank |β= 0.220, SE = 0.041, P = 9.99 × 10-8 for COPDGene) and chr 18 SNP rs11664369C > T nearest to the AC090771.2 gene (β = 0.129, SE = 0.024, P = 4.64 × 10-8 for UK Biobank |β = 0.203, SE = 0.045, P = 6.38 × 10-6 for COPDGene). Lower handgrip strength, a measure of muscle strength, but not FFMI was associated with reduced telomere length in the UK Biobank. Experimentally, in vitro knockdown of FTO lowered myotube diameter and induced a senescence-associated molecular phenotype, which was worsened by prolonged intermittent hypoxia and chronic hypoxia.

CONCLUSIONS

Genetic polymorphisms of FTO and AC090771.2 were associated with sarcopenia in COPD in independent cohorts. Knockdown of FTO in murine myotubes caused a molecular phenotype consistent with senescence that was exacerbated by hypoxia, a common condition in COPD. Genetic variation may interact with hypoxia and contribute to variable severity of sarcopenia and skeletal muscle molecular senescence phenotype in COPD.

CT pectoralis muscle area is associated with DXA lean mass and correlates with emphysema progression in a tobacco-exposed cohort

INTRODUCTION

Muscle loss is an important extrapulmonary manifestation of COPD. Dual energy X-ray absorptiometry (DXA) is the method of choice for body composition measurement but is not widely used for muscle mass evaluation. The pectoralis muscle area (PMA) is quantifiable by CT and predicts cross-sectional COPD-related morbidity. There are no studies that compare PMA with DXA measures or that evaluate longitudinal relationships between PMA and lung disease progression.

METHODS

Participants from our longitudinal tobacco-exposed cohort had baseline and 6-year chest CT (n=259) and DXA (n=164) data. Emphysema was quantified by CT density histogram parenchymal scoring using the 15th percentile technique. Fat-free mass index (FFMI) and appendicular skeletal mass index (ASMI) were calculated from DXA measurements. Linear regression model relationships were reported using standardised coefficient (β) with 95% CI.

RESULTS

PMA was more strongly associated with DXA measures than with body mass index (BMI) in both cross-sectional (FFMI: β=0.76 (95% CI 0.65 to 0.86), p<0.001; ASMI: β=0.76 (95% CI 0.66 to 0.86), p<0.001; BMI: β=0.36 (95% CI 0.25 to 0.47), p<0.001) and longitudinal (ΔFFMI: β=0.43 (95% CI 0.28 to 0.57), p<0.001; ΔASMI: β=0.42 (95% CI 0.27 to 0.57), p<0.001; ΔBMI: β=0.34 (95% CI 0.22 to 0.46), p<0.001) models. Six-year change in PMA was associated with 6-year change in emphysema (β=0.39 (95% CI 0.23 to 0.56), p<0.001) but not with 6-year change in airflow obstruction.

CONCLUSIONS

PMA is an accessible measure of muscle mass and may serve as a useful clinical surrogate for assessing skeletal muscle loss in smokers. Decreased PMA correlated with emphysema progression but not lung function decline, suggesting a difference in the pathophysiology driving emphysema, airflow obstruction and comorbidity risk.

Body Composition and COPD: A New Perspective

The proportion of obese or overweight patients in COPD patients is increasing. Although BMI, WC and other easy to measure indicators have been proven to be related to the risk of COPD, they cannot accurately reflect the distribution and changes of body composition, ignoring the body composition (such as fat distribution, muscle content, water content, etc.), the relationship between it and disease risk may be missed. By analyzing the correlation between different body composition indexes and COPD patients, we can provide new research ideas for the prognosis judgment or intervention of COPD disease.

Computed tomography-based body composition measures in COPD and their association with clinical outcomes: A systematic review

Background

Computed tomography (CT) is commonly utilized in chronic obstructive pulmonary disease (COPD) for lung cancer screening and emphysema characterization. Computed tomography-morphometric analysis of body composition (muscle mass and adiposity) has gained increased recognition as a marker of disease severity and prognosis. This systematic review aimed to describe the CT-methodology used to assess body composition and identify the association of body composition measures and disease severity, health-related quality of life (HRQL), cardiometabolic risk factors, respiratory exacerbations, and survival in patients with COPD.

Methods

Six databases were searched (inception-September 2021) for studies evaluating adult COPD patients using thoracic or abdominal CT-muscle or adiposity body composition measures. The systematic review was conducted in accordance with the PRISMA guidelines.

Results

Twenty eight articles were included with 15,431 COPD patients, across all GOLD stages with 77% males, age range (mean/median 59–78 years), and BMI range 19.8–29.3 kg/m². There was heterogeneity in assessment of muscle mass and adiposity using thoracic (n = 22) and abdominal (n = 8) CT-scans, capturing different muscle groups, anatomic locations, and adiposity compartments (visceral, subcutaneous, and epicardial). Low muscle mass and increased adiposity were associated with increased COPD severity measures (lung function, exercise capacity, dyspnea) and lower HRQL, but were not consistent across studies. Increased visceral adiposity (n = 6) was associated with cardiovascular disease or risk factors (hypertension, hyperlipidemia, and diabetes). Low muscle CSA was prognostic of respiratory exacerbations or mortality in three of six studies, whereas the relationship with increased intermuscular adiposity and greater mortality was only observed in one of three studies.

Conclusion

There was significant variability in CT-body composition measures. In several studies, low muscle mass was associated with increased disease severity and lower HRQL, whereas adiposity with cardiovascular disease/risk factors. Given the heterogeneity in body composition measures and clinical outcomes, the prognostic utility of CT-body composition in COPD requires further study.

Physical Activity, Exercise Capacity, and Body Composition in U.S. Veterans with Chronic Obstructive Pulmonary Disease

Rationale: Differences in body composition may contribute to variability in exercise capacity (EC) and physical activity (PA) in individuals with chronic obstructive pulmonary disease (COPD). Most studies have used bioimpedance-based surrogates of muscle (lean) mass; relatively few studies have included consideration of fat mass, and limited studies have been performed using dual X-ray absorptiometry (DXA) to assess body composition. Objectives: To determine whether DXA-assessed muscle (lean) and fat mass exhibit differential correlations with EC and PA in subjects with COPD. Methods: U.S. veterans with COPD (defined as forced expiratory volume in 1 second/forced vital capacity < 0.7 or emphysema on clinical chest computed tomography) had DXA-assessed body composition, EC (6-minute-walk distance), objective PA (average daily step counts), and self-reported PA measured at enrollment. Associations among EC, PA, and body composition were examined using Spearman correlations and multivariable models adjusted a priori for age, sex, race, and lung function. Results: Subjects (n = 98) were predominantly White (90%), obese (mean body mass index, 30.2 ± 6.2 kg/m2), and male (96%), with a mean age of 69.8 ± 7.9 years and moderate airflow obstruction (mean forced expiratory volume in 1 second percentage predicted, 68 ± 20%). Modest inverse correlations of EC and PA with fat mass were observed (Spearman's rho range, -0.20 to -0.34), whereas measures of muscle (lean) mass were not significantly associated with EC or PA. The ratio of appendicular skeletal muscle mass (ASM) to weight, which considers both muscle (lean) and fat mass, was consistently associated with EC (8.4 [95% confidence interval, 2.9-13.8] meter increase in 6-minute walk distance per 1% increase in ASM-to-weight ratio), objective PA (194.8 [95% confidence interval, 15.2-374.4] steps per day per 1% increase in ASM-to-weight ratio), and self-reported PA in multivariable-adjusted models. Conclusions: DXA-assessed body composition measures that include consideration of both lean and fat mass are associated with cross-sectional EC and PA in COPD populations. Clinical trial registered with www.clinicaltrials.gov (NCT02099799).

Extending the value of routine lung screening CT with quantitative body composition assessment

Certain body composition phenotypes, like sarcopenia, are well established as predictive markers for post-surgery complications and overall survival of lung cancer patients. However, their association with incidental lung cancer risk in the screening population is still unclear. We study the feasibility of body composition analysis using chest low dose computed tomography (LDCT). A two-stage fully automatic pipeline is developed to assess the cross-sectional area of body composition components including subcutaneous adipose tissue (SAT), muscle, visceral adipose tissue (VAT), and bone on T5, T8 and T10 vertebral levels. The pipeline is developed using 61 cases of the VerSe'20 dataset, 40 annotated cases of NLST, and 851 inhouse screening cases. On a test cohort consisting of 30 cases from the inhouse screening cohort (age 55 - 73, 50% female) and 42 cases of NLST (age 55 - 75, 59.5% female), the pipeline achieves a root mean square error (RMSE) of 7.25 mm (95% CI: [6.61, 7.85]) for the vertebral level identification and mean Dice similarity score (DSC) 0.99 ± 0.02, 0.96 ± 0.03, and 0.95 ± 0.04 for SAT, muscle, and VAT, respectively for body composition segmentation. The pipeline is generalized to the CT arm of the NLST dataset (25,205 subjects, 40.8% female, 1,056 lung cancer incidences). Time-to-event analysis for lung cancer incidence indicates inverse association between measured muscle cross-sectional area and incidental lung cancer risks (p < 0.001 female, p < 0.001 male). In conclusion, automatic body composition analysis using routine lung screening LDCT is feasible.

Correlation Between Bioelectrical Impedance Analysis and Chest CT-Measured Erector Spinae Muscle Area: A Cross-Sectional Study

BACKGROUND

Skeletal muscle mass (SMM) plays an important part in diverse health and disease states. Bioelectrical impedance analysis (BIA) and computed tomography (CT) are available for its assessment. However, muscle mass assessed by BIA may be influenced by multiple factors. The erector spinae muscle area (ESA) on chest CT is recently presumed to be representative of SMM. This study aimed to derive BIA from the ESA and evaluate the magnitude of association (between ESA measured from chest CT) and BIA.

METHODS

Subjects hospitalized for health checkups between December 2020 and December 2021, having undergone both BIA (50 kHz, 0.8 mA) and chest CT, were included. ESA was quantified at the level of the 12th thoracic vertebra (T12-ESA) by a standardized semi-automated segmentation algorithm. Low SMM was defined using the Asian Working Group for Sarcopenia criteria. The association between T12-ESA and BIA was then evaluated. Stratified analyses by sex and BMI were also performed.

RESULTS

Among 606 included subjects (59.7 ± 16.6 years, 63.5% male), 110 (18.2%) had low SMM. BMI in low and normal SMM groups was 20.1 and 24.7 kg/m², respectively. Current smoking, drinking, chronic obstructive pulmonary disease, and chronic renal dysfunction were more frequently seen in the low SMM group than in the normal SMM group. The final regression model included T12-ESA, weight, BMI, and age, and had an adjusted R² of 0.806 with BIA. In the validation group, the correlation between T12-ESA-derived BIA and BIA remained high (Pearson correlation = 0.899). Stratified analysis disclosed a stronger correlation between T12-ESA and BIA in male subjects than in female subjects (adjusted R² = 0.790 vs. adjusted R² = 0.711, p < 0.05), and a better correlation was observed in obese (BMI ≥ 30 kg/m²) compared with underweight (BMI < 18.5 kg/m²) subjects (adjusted R^{2 =} 0.852 vs. adjusted R² = 0.723, p < 0.05). Additional analysis revealed a significant correlation between T12-ESA and skeletal muscle cross-sectional area at the 3rd lumbar vertebra (L3-CSA) (adjusted R² = 0.935, p < 0.001).

CONCLUSIONS

CT-based assessment of ESA at the T12 level is feasible and correlated well with BIA, especially in male subjects and obese subjects.

Longitudinal association between muscle loss and mortality in ever-smokers

BACKGROUND

Body composition measures, specifically low weight or reduced muscle mass, are associated with mortality in chronic obstructive pulmonary disease (COPD), but the effect of longitudinal body composition changes is undefined.

RESEARCH QUESTION

Is the longitudinal loss of fat-free mass (FFM) associated with increased mortality including in those with initially normal or elevated body composition metrics?

STUDY DESIGN AND METHODS

Participants with complete data for at least one visit in the COPDGene (n=9,268) and ECLIPSE studies (1,760) were included and followed for 12 and 8 years, respectively. Pectoralis muscle area (PMA) was derived from thoracic CT scans and used as a proxy for FFM. A longitudinal mixed sub-model for PMA and a Cox proportional hazards sub-model for survival were fitted on a joint distribution using a shared random intercept parameter and Markov chain Monte Carlo parameter estimation.

RESULTS

Both cohorts demonstrated a left shifted distribution of baseline FFM, not reflected in BMI, and an increase in all-cause mortality risk associated with longitudinal loss of PMA. For each one cm2 PMA loss, mortality increased 3.1% (95% CI 2.4, 3.7, p<0.001) in COPDGene, and 2.4% (95% CI 0.9, 4.0, p<0.001) in ECLIPSE. Increased mortality risk was independent of enrollment values for BMI and disease severity (BODE index quartiles) and was significant even in participants with initially greater than average PMA.

INTERPRETATION

Longitudinal loss of PMA is associated with increased all-cause mortality, regardless of BMI or initial muscle mass. Consideration of novel screening tests and further research into mechanisms contributing to muscle decline may improve risk stratification and identify novel therapeutic targets in ever-smokers.

Association of cardiovascular health with mortality among COPD patients: National Health and Nutrition Examination Survey III

BACKGROUND

All-cause and cardiovascular disease (CVD) mortality are higher among patients with chronic obstructive pulmonary disease (COPD). We examined the association between American Heart Association's Life's Simple 7 (LS7) metrics and all-cause as well as CVD mortality in patients with COPD.

METHODS

We examined 1513 US adults with COPD aged ≥ 40, without prior CVD, from the National Health and Nutrition Examination Survey III. COPD was defined as FEV₁/FVC<0.7 in absence of asthma. Adjusted Cox regression was used to assess the relation of LS7 metrics with all-cause and CVD mortality.

RESULTS

Overall, only 74 participants (4.9%) had ideal 5-7 LS7 metrics. Over a mean follow-up of 14.2±7.9 years, 1162 individuals died, of which 315 were due to CVD. Age, sex, and ethnicity-adjusted HRs (95% CI) for all-cause mortality were 0.53 (0.41-0.68), 0.45 (0.34-0.59), 0.66 (0.49-0.87) and 0.75 (0.56-1.00) among those with ideal vs poor control of smoking, diet, physical activity and fasting blood glucose, respectively. However, the ideal and intermediate LS7 metrics were not significantly associated with lower risk of CVD mortality, except for a BMI between 25-29.9 kg/m². Those with 5-7 vs 0-1 ideal metrics had adjusted HRs 0.50 (0.40-0.87) for all-cause and 0.53 (0.21-1.36) for CVD mortality.

CONCLUSION

Ideal levels of multiple behavioral and health factors are associated with substantially lower risks for all-cause mortality, with a trend for lower CVD mortality among US adults with COPD.

Psoas Muscle Density Evaluated by Chest CT and Long-Term Mortality in COPD Patients

RATIONALE

Poor muscle quality in COPD patients relates to exercise intolerance and mortality. Muscle quality can be estimated on computed tomography (CT) by estimating psoas density (PsD). We tested the hypothesis that PsD is lower in COPD patients than in controls and relates to all-cause mortality.

METHODS

At baseline, PsD was measured using axial low-dose chest CT images in 220 COPD patients, 80% men, who were 65±8 years old with mild to severe airflow limitation and in a control group of 58 subjects matched by age, sex, body mass index (BMI) and body surface area (BSA). COPD patients were prospectively followed for 76.5 (48-119) months. Anthropometrics, smoking history, BMI, dyspnoea, lung function, exercise capacity, BODE index and exacerbations history were recorded. Cox proportional risk analysis determined the factors more strongly associated with long-term mortality.

RESULTS

PsD was lower in COPD patients than in controls (40.5 vs 42.5, p=0.045). During the follow-up, 54 (24.5%) deaths occurred in the COPD group. PsD as well as age, sex, pack-year history, FEV₁%, 6MWD, mMRC, BODE index, were independently associated with mortality. Multivariate analysis showed that age (HR 1.06; 95% CI 1.02-1.12, p=0.006) and CT-assessed PsD (HR 0.97; 95%CI 0.94-0.99, p=0.023) were the variables independently associated with all-cause mortality.

CONCLUSIONS

In COPD patients with mild to severe airflow limitation, chest CT-assessed psoas muscle density was lower than in matched controls and independently associated with long-term mortality. Muscle quality using the easy to evaluate psoas muscle density from chest CT may provide clinicians with important prognostic information in COPD.

Pectoralis muscle area and its association with indices of disease severity in interstitial lung disease

RATIONALE

The pathophysiology of interstitial lung disease (ILD) impacts body composition, whereby ILD severity is linked to lower lean mass.

OBJECTIVES

To determine i) if pectoralis muscle area (PMA) is a surrogate for whole-body lean mass in ILD, ii) whether PMA is associated with ILD severity, and iii) if the longitudinal change in PMA is associated with pulmonary function and mortality in ILD.

METHODS

Patients with ILD (n = 164) were analyzed retrospectively. PMA was quantified from a chest computed tomography scan. Peripheral oxygen saturation (SpO₂), 6-min walk distance (6MWD), and pulmonary function were obtained as part of routine clinical care. Dyspnea and quality of life were assessed using the UCSD Shortness of Breath Questionnaire and European Quality of Life 5 Dimensions questionnaire, respectively.

RESULTS

PMA was associated with whole-body lean mass (p < 0.001). After adjusting for age, sex, height, body mass, and prednisone status, PMA was associated with %-predicted forced vital capacity (FVC), %-predicted diffusion capacity (DL_CO), resting and exertional SpO₂, and dyspnea (all p < 0.05), but not forced expiratory volume in 1 s (FEV₁), FEV₁/FVC, 6MWD, or quality of life (all p > 0.05). The annual negative PMA slope was associated with annual negative slopes in FVC, FEV₁, and DL_CO (all p < 0.05), but not FEV₁/FVC (p = 0.46). Annual slope in PMA was associated with all-cause mortality (hazard ratio = -0.80, 95% CI:0.889-0.959; p < 0.001).

CONCLUSION

In patients with ILD, PMA is a suitable surrogate for whole-body lean mass. A lower PMA is associated with indices of ILD severity, which supports the notion that ILD progression may involve sarcopenia.

Intramuscular and Intermuscular Abdominal Fat Infiltration in COPD: A Propensity Score Matched Study

Purpose

Low-attenuation muscle area (LAMA) and normal-attenuation muscle area (NAMA) indicate lipid-rich and lipid-poor skeletal muscle areas, respectively. Additionally, intermuscular adipose tissue (IMAT) indicates localized fat between muscle groups. In this study, we aimed to evaluate the intramuscular and intermuscular fat infiltration in individuals with chronic obstructive pulmonary disease (COPD) by performing quantitative assessment of the LAMA, NAMA, and IMAT observed on abdominopelvic computed tomography (APCT) images.

Patients and Methods

We performed a cross-sectional study using data of subjects who underwent a general health examination with APCT at Ulsan University Hospital between March 2014 and June 2019. We classified the subjects into control and COPD groups based on age, smoking history, and pulmonary function results. We compared the attenuation and body mass index adjusted area of intra-abdominal components between the two groups using propensity score matching. We also evaluated these outcomes in COPD subgroups (mild and moderate stage subjects).

Results

Overall, 6,965 subjects were initially enrolled, and 250 pairs of control and COPD subjects were selected after propensity score matching. The NAMA attenuation (unstandardized β=−1.168, P<0.001) was lower, and the IMAT (unstandardized β=0.042, P=0.006) and LAMA (unstandardized β=0.120, P<0.001) indexes were greater in the COPD group than in the control group. In subgroup analysis, those with mild and moderate COPD also had high IMAT (unstandardized β=0.037, P=0.009 and unstandardized β=0.045, P<0.001) and LAMA (unstandardized β=0.089, P=0.002 and unstandardized β=0.147, P<0.001) indexes compared to the control subjects. However, the NAMA attenuation (unstandardized β=−1.075, P<0.001) and NAMA index (unstandardized β=−0.133, P=0.015) were significantly lower in moderate COPD subjects only.

Conclusion

Our study showed that intramuscular and intermuscular abdominal fat infiltration could be present in subjects with mild COPD, and it might be exacerbated in those with moderate COPD.

C. Silva T, Bluemke DA, Budoff M, Barr RG, Allison MA, Bertoni AG, Post WS, Lima JAC, Demehri S. Adipose tissue biomarkers and type 2 diabetes incidence in normoglycemic participants in the MESArthritis Ancillary Study: A cohort study

BACKGROUND

Given the central role of skeletal muscles in glucose homeostasis, deposition of adipose depots beneath the fascia of muscles (versus subcutaneous adipose tissue [SAT]) may precede insulin resistance and type 2 diabetes (T2D) incidence. This study was aimed to investigate the associations between computed tomography (CT)-derived biomarkers for adipose tissue and T2D incidence in normoglycemic adults.

METHODS AND FINDINGS

This study was a population-based multiethnic retrospective cohort of 1,744 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) with normoglycemia (baseline fasting plasma glucose [FPG] less than 100 mg/dL) from 6 United States of America communities. Participants were followed from April 2010 and January 2012 to December 2017, for a median of 7 years. The intermuscular adipose tissue (IMAT) and SAT areas were measured in baseline chest CT exams and were corrected by height squared (SAT and IMAT indices) using a predefined measurement protocol. T2D incidence, as the main outcome, was based on follow-up FPG, review of hospital records, or self-reported physician diagnoses. Participants' mean age was 69 ± 9 years at baseline, and 977 (56.0%) were women. Over a median of 7 years, 103 (5.9%) participants were diagnosed with T2D, and 147 (8.4%) participants died. The IMAT index (hazard ratio [HR]: 1.27 [95% confidence interval [CI]: 1.15-1.41] per 1-standard deviation [SD] increment) and the SAT index (HR: 1.43 [95% CI: 1.16-1.77] per 1-SD increment) at baseline were associated with T2D incidence over the follow-up. The associations of the IMAT and SAT indices with T2D incidence were attenuated after adjustment for body mass index (BMI) and waist circumference, with HRs of 1.23 (95% CI: 1.09-1.38) and 1.29 (95% CI: 0.96-1.74) per 1-SD increment, respectively. The limitations of this study include unmeasured residual confounders and one-time measurement of adipose tissue biomarkers.

CONCLUSIONS

In this study, we observed an association between IMAT at baseline and T2D incidence over the follow-up. This study suggests the potential role of intermuscular adipose depots in the pathophysiology of T2D.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00005487.

Psoas Muscle Density Evaluated by Chest CT and Long-Term Mortality in COPD Patients

RATIONALE

Poor muscle quality in COPD patients relates to exercise intolerance and mortality. Muscle quality can be estimated on computed tomography (CT) by estimating psoas density (PsD). We tested the hypothesis that PsD is lower in COPD patients than in controls and relates to all-cause mortality.

METHODS

At baseline, PsD was measured using axial low-dose chest CT images in 220 COPD patients, 80% men, who were 65±8 years old with mild to severe airflow limitation and in a control group of 58 subjects matched by age, sex, body mass index (BMI) and body surface area (BSA). COPD patients were prospectively followed for 76.5 (48-119) months. Anthropometrics, smoking history, BMI, dyspnoea, lung function, exercise capacity, BODE index and exacerbations history were recorded. Cox proportional risk analysis determined the factors more strongly associated with long-term mortality.

RESULTS

PsD was lower in COPD patients than in controls (40.5 vs 42.5, p=0.045). During the follow-up, 54 (24.5%) deaths occurred in the COPD group. PsD as well as age, sex, pack-year history, FEV1%, 6MWD, mMRC, BODE index, were independently associated with mortality. Multivariate analysis showed that age (HR 1.06; 95% CI 1.02-1.12, p=0.006) and CT-assessed PsD (HR 0.97; 95%CI 0.94-0.99, p=0.023) were the variables independently associated with all-cause mortality.

CONCLUSIONS

In COPD patients with mild to severe airflow limitation, chest CT-assessed psoas muscle density was lower than in matched controls and independently associated with long-term mortality. Muscle quality using the easy to evaluate psoas muscle density from chest CT may provide clinicians with important prognostic information in COPD.

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

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 (ρ = 0.80; 95% CI: 0.78, 0.81; P < .001) and IMAT indexes (ρ = 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. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Sverzellati and Cademartiri in this issue.

Respiratory exacerbations are associated with muscle loss in current and former smokers

OBJECTIVES

Muscle wasting is a recognised extra-pulmonary complication in chronic obstructive pulmonary disease and has been associated with increased risk of death. Acute respiratory exacerbations are associated with reduction of muscle function, but there is a paucity of data on their long-term effect. This study explores the relationship between acute respiratory exacerbations and long-term muscle loss using serial measurements of CT derived pectoralis muscle area (PMA).

DESIGN AND SETTING

Participants were included from two prospective, longitudinal, observational, multicentre cohorts of ever-smokers with at least 10 pack-year history.

PARTICIPANTS

The primary analysis included 1332 (of 2501) participants from Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) and 4384 (of 10 198) participants from Genetic Epidemiology of COPD (COPDGene) who had complete data from their baseline and follow-up visits.

INTERVENTIONS

PMA was measured on chest CT scans at two timepoints. Self-reported exacerbation data were collected from participants in both studies through the use of periodic longitudinal surveys.

MAIN OUTCOME MEASURES

Age-related and excess muscle loss over time.

RESULTS

Age, sex, race and body mass index were associated with baseline PMA. Participants experienced age-related decline at the upper end of reported normal ranges. In ECLIPSE, the exacerbation rate over time was associated with an excess muscle area loss of 1.3% (95% CI 0.6 to 1.9, p<0.001) over 3 years and in COPDGene with an excess muscle area loss of 2.1% (95% CI 1.2 to 2.8, p<0.001) over 5 years. Excess muscle area decline was absent in 273 individuals who participated in pulmonary rehabilitation.

CONCLUSIONS

Exacerbations are associated with accelerated skeletal muscle loss. Each annual exacerbation was associated with the equivalent of 6 months of age-expected decline in muscle mass. Ameliorating exacerbation-associated muscle loss represents an important therapeutic target.

CT Imaging and Comorbidities in COPD: Beyond Lung Cancer Screening

Comorbidities significantly contribute to morbidity, mortality, and health-care costs in individuals with COPD. Comorbidity prevalence does not always correlate with lung disease severity, and the elevated risk of certain comorbidities is often independent of shared risk factors such as tobacco burden. Although COPD management guidelines recognize the importance of identifying and treating comorbidities as part of the comprehensive management of COPD patients, little guidance is provided regarding best screening practices. Whereas universal comorbidity screening in COPD patients is likely not cost-effective, targeted early screening and treatment in those at highest risk may have a significant impact on COPD outcomes. Recent studies suggest that certain radiographic features on thoracic imaging may serve as surrogate markers of comorbidity in patients with COPD. This review evaluates these studies in the context of the growing availability of chest CT scans in the lung cancer screening era and discusses how chest CT imaging can be leveraged to identify those COPD patients at highest risk for comorbid disease.

Managing malnutrition in COPD: A review

In the UK approximately 1.2 million people have COPD with around 25-40% being underweight and 35% have a severely low fat-free mass index. Measuring their body mass index is recommended and Health care professionals should endeavour to ensure that COPD patients are achieving their nutritional requirements. A narrative review summarizes evidence from 28 original articles identified through a systematic searches of databases, grey literature and hand searches covering 15 years, focusing on two themes, on the impact of malnutrition on COPD, and the management of malnutrition in COPD. Malnutrition causes negative effects on exercise and muscle function and lung function as well as increasing exacerbations, mortality and cost. Management options include nutritional supplementation which may increase weight and muscle function. Nutritional education has short-term improvements. Malnutrition affects multiple aspects of COPD, but treatment is of benefit. Clinical practice should include nutrition management.

Advances in Chronic Obstructive Pulmonary Disease Imaging

Chest computed tomography (CT) imaging is a useful tool that provides in vivo information regarding lung structure. Imaging has contributed to a better understanding of COPD, allowing for the detection of early structural changes and the quantification of extra-pulmonary structures. Novel CT imaging techniques have provided insight into the progression of the main COPD subtypes, such as emphysema and small airway disease. This article serves as a review of new information relevant to COPD imaging. CT abnormalities, such as emphysema and loss of airways, are present even in smokers who do not meet the criteria for COPD and in those with mild-to-moderate disease. Subjects with mild-to-moderate COPD, with the highest loss of airways, also experience the highest decline in lung function. Extra-pulmonary manifestations of COPD, such as right ventricle enlargement and low muscle mass measured on CT, are associated with increased risk for all-cause mortality. CT longitudinal data has also given insight into the progression of COPD. Mechanically affected areas of lung parenchyma adjacent to emphysematous areas are associated with a greater decline in FEV₁. Subjects with the greatest percentage of small airway disease, as measured on matched inspiratory-expiratory CT scan, also present with the greatest decline in lung function.

Low pectoralis muscle index, cavitary nodule or mass and segmental to lobar consolidation as predictors of primary multidrug-resistant tuberculosis: A comparison with primary drug sensitive tuberculosis

Background

The loss of muscle mass in primary multidrug-resistant tuberculosis (MDR-TB) has not been examined in previous studies. This study aimed to investigate that low pectoralis muscle index and characteristic CT features can help differentiate patients with primary MDR-TB from those with drug-sensitive tuberculosis (DS-TB).

Material and methods

From 2010 to 2016, we retrospectively enrolled 90 patients with primary MDR-TB and 90 age- and sex-matched patients with primary DS-TB. The pectoralis muscle mass was quantitatively measured on axial CT images using density histogram analysis. The pectoralis muscle index (PMI) was defined as the pectoralis muscle mass divided by body mass index. We compared the PMI and characteristic CT features of pulmonary tuberculosis between the two groups.

Results

Low PMI, segmental to lobar consolidation, cavity in consolidation, cavitary nodule or mass, and bilateral involvement were more frequently observed in patients with MDR-TB than in those with DS-TB. In stepwise multivariate logistic regression analysis, low PMI (odds ratio, 2.776; 95% confidence interval, 1.450–5.314; p = 0.002), segmental or lobar consolidation (odds ratio, 3.123; 95% confidence interval, 1.629–5.987; p = 0.001), and cavitary nodule or mass (odds ratio, 2.790; 95% confidence interval, 1.348–5.176; p = 0.002) were significant factors for MDR-TB.

Conclusion

Low pectoralis muscle index, segmental to lobar consolidation and cavitary nodule or mass can help differentiate primary MDR-TB from DS-TB.

Diagnosis, prevalence, and clinical impact of sarcopenia in COPD: a systematic review and meta-analysis

Sarcopenia prevalence and its clinical impact are reportedly variable in chronic obstructive pulmonary disease (COPD) due partly to definition criteria. This review aimed to identify the criteria used to diagnose sarcopenia and the prevalence and impact of sarcopenia on health outcomes in people with COPD. This review was registered in PROSPERO (CRD42018092576). Five electronic databases were searched to August 2018 to identify studies related to sarcopenia and COPD. Study quality was assessed using validated instruments matched to study designs. Sarcopenia prevalence was determined using authors' definitions. Comparisons were made between people who did and did not have sarcopenia for pulmonary function, exercise capacity, quality of life, muscle strength, gait speed, physical activity levels, inflammation/oxidative stress, and mortality. Twenty-three studies (70% cross-sectional) from Europe (10), Asia (9), and North and South America (4) involving 9637 participants aged ≥40 years were included (69.5% men). Sarcopenia criteria were typically concordant with recommendations of hEuropean and Asian consensus bodies. Overall sarcopenia prevalence varied from 15.5% [95% confidence interval (CI) 11.8-19.1; combined muscle mass, strength, and/or physical performance criteria] to 34% (95%CI 20.6-47.3; muscle mass criteria alone) (P = 0.009 between subgroups) and was greater in people with more severe [37.6% (95%CI 24.8-50.4)] versus less severe [19.1% (95%CI 10.2-28.0)] lung disease (P = 0.020), but similar between men [41.0% (95%CI 26.2-55.9%)] and women [31.9% (95%CI 7.0-56.8%)] (P = 0.538). People with sarcopenia had lower predicted forced expiratory volume in the first second (mean difference -7.1%; 95%CI -9.0 to -5.1%) and poorer exercise tolerance (standardized mean difference -0.8; 95%CI -1.4 to -0.2) and quality of life (standardized mean difference 0.26; 95%CI 0.2-0.4) compared with those who did not (P < 0.001 for all). No clear relationship was observed between sarcopenia and inflammatory or oxidative stress biomarkers. Incident mortality was unreported in the literature. Sarcopenia is prevalent in a significant proportion of people with COPD and negatively impacts upon important clinical outcomes. Opportunities exist to optimize its early detection and management and to evaluate its impact on mortality in this patient group.

Chest computed tomography is a valid measure of body composition in individuals with advanced lung disease

There is growing interest in evaluating body composition using routine clinical computed tomography (CT) scans; however, the validity of this technique in lung transplant patients has not been described. The study objectives were to determine the reliability of measuring fat compartments from thoracic CT and evaluate the validity of muscle and fat cross-sectional area (CSA) from thoracic CT by comparing to bioelectrical impedance analysis (BIA). Thoracic CT scans from lung transplant assessments were obtained for analysis. Total thoracic muscle CSA, pectoral muscle CSA, subcutaneous adipose tissue (SAT), and mediastinal adipose tissue (MAT) were manually segmented by two independent raters. Reliability was analysed using intra-class correlation coefficient (ICC). Correlations were determined between CT measures with fat-free mass index (FFMI), body fat mass index (BFMI) and per cent body fat (%BF) from BIA; and anthropometrics [body mass index (BMI) and waist circumference (WC)]. High inter- and intra-rater reliability were found for SAT and MAT (ICCs = 0.99). Pectoral and total muscle CSA were correlated with FFMI (r = .41, p = .003 and r = .57, p < .001, respectively). SAT was associated with whole-body fat from BIA and with BMI and WC (r = .61 to .80, p < .001). MAT was associated with BMI (r = .58, p < .001) and WC (r = .61, p < .001). This study supports the reliability and validity of using thoracic CT to measure muscle and fat. Future studies are needed to investigate whether these CT-based measures are predictive of clinical and post-transplant outcomes in advanced lung disease.

Heme metabolism genes Downregulated in COPD Cachexia

INTRODUCTION

Cachexia contributes to increased mortality and reduced quality of life in Chronic Obstructive Pulmonary Disease (COPD) and may be associated with underlying gene expression changes. Our goal was to identify differential gene expression signatures associated with COPD cachexia in current and former smokers.

METHODS

We analyzed whole-blood gene expression data from participants with COPD in a discovery cohort (COPDGene, N = 400) and assessed replication (ECLIPSE, N = 114). To approximate the consensus definition using available criteria, cachexia was defined as weight-loss > 5% in the past 12 months or low body mass index (BMI) (< 20 kg/m2) and 1/3 criteria: decreased muscle strength (six-minute walk distance < 350 m), anemia (hemoglobin < 12 g/dl), and low fat-free mass index (FFMI) (< 15 kg/m2 among women and < 17 kg/m2 among men) in COPDGene. In ECLIPSE, cachexia was defined as weight-loss > 5% in the past 12 months or low BMI and 3/5 criteria: decreased muscle strength, anorexia, abnormal biochemistry (anemia or high c-reactive protein (> 5 mg/l)), fatigue, and low FFMI. Differential gene expression was assessed between cachectic and non-cachectic subjects, adjusting for age, sex, white blood cell counts, and technical covariates. Gene set enrichment analysis was performed using MSigDB.

RESULTS

The prevalence of COPD cachexia was 13.7% in COPDGene and 7.9% in ECLIPSE. Fourteen genes were differentially downregulated in cachectic versus non-cachectic COPD patients in COPDGene (FDR < 0.05) and ECLIPSE (FDR < 0.05).

DISCUSSION

Several replicated genes regulating heme metabolism were downregulated among participants with COPD cachexia. Impaired heme biosynthesis may contribute to cachexia development through free-iron buildup and oxidative tissue damage.

Quantitative computed tomography measures of skeletal muscle mass in patients with idiopathic pulmonary fibrosis according to a multidisciplinary discussion diagnosis: A retrospective nationwide study in Japan

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive disease often accompanied by skeletal muscle wasting. We investigated whether skeletal muscle mass and muscle attenuation on computed tomography (CT) are predictors of mortality in IPF patients, using a nationwide cloud-based database and web-based multidisciplinary discussion (MDD) system.

METHODS

IPF patients diagnosed using MDD from April 2009 to March 2014 were included. We analyzed the cross-sectional area (CSA) of the erector spinae muscle (ESM_CSA) and the pectoralis muscle (PM_CSA), muscle attenuation of the ESM (ESM_MA), and PM (PM_MA) on single-slice axial CT. Survival probability was assessed using the Kaplan-Meier method and compared by the log-rank test. Multivariate Cox proportional hazards models were used to evaluate the relationship among the ESM_CSA, PM_CSA, ESM_MA, PM_MA, clinical parameters, and prognosis.

RESULTS

A total of 199 IPF patients were enrolled. Seventy-four patients died during the study period and the most frequent cause was acute exacerbation (13.1%). The group with the lowest quartile of ESM_CSA had significantly worse survival than other groups (P = 0.009). Survival rates of the groups with the lowest quartile of PM_CSA, lower ESM_MA, and lower PM_MA did not differ from those of other groups. According to multivariate analysis, ESM_CSA < lower quartile was significantly associated with all-cause mortality (hazards ratio, 1.96; P = 0.030), whereas, ESM_MA < median, PM_CSA < lower quartile, and PM_MA < median were not.

CONCLUSIONS

Low ESM_CSA on CT images may be a strong risk factor for all-cause mortality in IPF patients based on MDD diagnosis.

Computed tomography-derived area and density of pectoralis muscle associated disease severity and longitudinal changes in chronic obstructive pulmonary disease: a case control study

BACKGROUND

Muscle wasting is associated with prognosis in patients with chronic obstructive pulmonary disease (COPD). The cross-sectional area of skeletal muscles on computed tomography (CT) could serve as a method to evaluate body composition. The present study aimed to determine the ability of CT-derived pectoralis muscle area (PMA) and pectoralis muscle density (PMD) to determine the severity of COPD and change in longitudinal pulmonary function in patients with COPD.

METHODS

A total of 293 participants were enrolled in this study, a whom 222 had undergone at least two spirometry measurements within 3 years after baseline data acquisition. PMA and PMD were measured from a single axial slice of chest CT above the aortic arch at baseline. The emphysema index and bronchial wall thickness were quantitatively assessed in all scans. The generalized linear model was used to determine the correlation between PMA and PMD measurements and pulmonary function.

RESULTS

PMA and PMD were significantly associated with baseline lung function and the severity of emphysema (P < 0.05). Patients with the lowest PMA and PMD exhibited significantly more severe airflow obstruction (β = - 0.06; 95% confidence interval: - 0.09 to - 0.03]. PMA was statistically associated with COPD assessment test (CAT) score (P = 0.033). However, PMD did not exhibit statistically significant correlation with either CAT scores or modified Medical Research Council scores (P > 0.05). Furthermore, neither PMA nor PMD were associated with changes in forced expiratory volume in 1 s over a 3-year periods.

CONCLUSIONS

CT-derived features of the pectoralis muscle may be helpful in predicting disease severity in patients with COPD, but are not necessarily associated with longitudinal changes in lung function.