Body composition and resting energy expenditure in clinically stable, non-weight-losing patients with severe emphysema

Brown adipose tissue activation is not related to hypermetabolism in emphysematous chronic obstructive pulmonary disease patients

BACKGROUND

Brown adipose tissue (BAT) has been primarily researched as a potential target for mitigating obesity. However, the physiological significance of BAT in relation to cachexia remains poorly understood. The objective of this study was to investigate the putative contribution of BAT on different components of energy metabolism in emphysematous chronic obstructive pulmonary disease (COPD) patients.

METHODS

Twenty COPD patients (mean ± SD age 62 ± 6, 50% female, median [range] BMI 22.4 [15.1-32.5] kg/m² and 85% low FFMI) were studied. Basal metabolic rate (BMR) was assessed by ventilated hood, total daily energy expenditure (TDEE) by doubly labelled water and physical activity by triaxial accelerometry. BMR was adjusted for fat-free mass (FFM) as assessed by deuterium dilution. Analysis of BAT and WAT was conducted in a subset of ten patients and six age-matched, gender-matched and BMI-matched healthy controls. BAT glucose uptake was assessed by means of cold-stimulated integrated [18F]FDG positron-emission tomography and magnetic resonance imaging. WAT was collected from subcutaneous abdominal biopsies to analyse metabolic and inflammatory gene expression levels. Lung function was assessed by spirometry and body plethysmography and systemic inflammation by high sensitivity C-reactive protein.

RESULTS

Mean TDEE was 2209 ± 394 kcal/day, and mean BMR was 1449 ± 214 kcal/day corresponding to 120% of predicted. FFM-adjusted BMR did not correlate with lung function or C-reactive protein. Upon cooling, energy expenditure increased, resulting in a non-shivering thermogenesis of (median [range]) 20.1% [3.3-41.3] in patients and controls. Mean BAT glucose uptake was comparable between COPD and controls (1.5 [0.1-6.2] vs. 1.1 [0.7-3.9]). In addition, no correlation was found between BMR adjusted for FFM and BAT activity or between cold-induced non-shivering energy expenditure and BAT activity. Gene expression levels of the brown adipocyte or beige markers were also comparable between the groups. No (serious) adverse events were reported.

CONCLUSIONS

Although COPD patients were hypermetabolic at rest, no correlation was found between BMR or TDEE and BAT activity. Furthermore, both BAT activity and gene expression levels of the brown adipocyte or beige markers were comparable between COPD patients and controls.

Effect of Bronchoscopic Lung Volume Reduction in Advanced Emphysema on Energy Balance Regulation

BACKGROUND

Hypermetabolism and muscle wasting frequently occur in patients with severe emphysema. Improving respiratory mechanics by bronchoscopic lung volume reduction (BLVR) might contribute to muscle maintenance by decreasing energy requirements and alleviating eating-related dyspnoea.

OBJECTIVE

The goal was to assess the impact of BLVR on energy balance regulation.

DESIGN

Twenty emphysematous subjects participated in a controlled clinical experiment before and 6 months after BLVR. Energy requirements were assessed: basal metabolic rate (BMR) by ventilated hood, total daily energy expenditure (TDEE) by doubly labelled water, whole body fat-free mass (FFM) by deuterium dilution, and physical activity by accelerometry. Oxygen saturation, breathing rate, and heart rate were monitored before, during, and after a standardized meal via pulse oximetry and dyspnoea was rated.

RESULTS

Sixteen patients completed follow-up, and among those, 10 patients exceeded the minimal clinically important difference of residual volume (RV) reduction. RV was reduced with median (range) 1,285 mL (-2,430, -540). Before BLVR, 90% of patients was FFM-depleted despite a normal BMI (24.3 ± 4.3 kg/m2). BMR was elevated by 130%. TDEE/BMR was 1.4 ± 0.2 despite a very low median (range) daily step count of 2,188 (739, 7,110). Following BLVR, the components of energy metabolism did not change significantly after intervention compared to before intervention, but BLVR treatment decreased meal-related dyspnoea (4.1 vs. 1.7, p = 0.019).

CONCLUSIONS

Impaired respiratory mechanics in hyperinflated emphysematous patients did not explain hypermetabolism. Clinical Trial Registry Number: NCT02500004 at www.clinicaltrial.gov.

Cachexia in chronic obstructive pulmonary disease: new insights and therapeutic perspective

Cachexia and muscle wasting are well recognized as common and partly reversible features of chronic obstructive pulmonary disease (COPD), adversely affecting disease progression and prognosis. This argues for integration of weight and muscle maintenance in patient care. In this review, recent insights are presented in the diagnosis of muscle wasting in COPD, the pathophysiology of muscle wasting, and putative mechanisms involved in a disturbed energy balance as cachexia driver. We discuss the therapeutic implications of these new insights for optimizing and personalizing management of COPD-induced cachexia.

Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE)

An increasing recognition has emerged of the complexities of the global health agenda—specifically, the collision of infections and noncommunicable diseases and the dual burden of over- and undernutrition. Of particular practical concern are both 1) the need for a better understanding of the bidirectional relations between nutritional status and the development and function of the immune and inflammatory response and 2) the specific impact of the inflammatory response on the selection, use, and interpretation of nutrient biomarkers. The goal of the Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE) is to provide guidance for those users represented by the global food and nutrition enterprise. These include researchers (bench and clinical), clinicians providing care/treatment, those developing and evaluating programs/interventions at scale, and those responsible for generating evidence-based policy. The INSPIRE process included convening 5 thematic working groups (WGs) charged with developing summary reports around the following issues: 1) basic overview of the interactions between nutrition, immune function, and the inflammatory response; 2) examination of the evidence regarding the impact of nutrition on immune function and inflammation; 3) evaluation of the impact of inflammation and clinical conditions (acute and chronic) on nutrition; 4) examination of existing and potential new approaches to account for the impact of inflammation on biomarker interpretation and use; and 5) the presentation of new approaches to the study of these relations. Each WG was tasked with synthesizing a summary of the evidence for each of these topics and delineating the remaining gaps in our knowledge. This review consists of a summary of the INSPIRE workshop and the WG deliberations.

Circulating leptin concentrations in patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis

BACKGROUND

Weight loss is a clinically important risk factor indicating a poor prognosis in chronic obstructive pulmonary disease (COPD). Leptin is an important regulator of food intake and energy expenditure.

OBJECTIVES

To conduct a meta-analysis to determine whether the level of leptin is related to the disease status of COPD.

METHODS

Studies published before December 2012 were identified by searching PubMed, Embase and the Cochrane Database. Observational studies comparing circulating leptin levels between COPD patients and healthy controls were included. Data were independently extracted by two investigators and analyzed using Stata 12.0 software.

RESULTS

Ten articles were included in the meta-analysis. Circulating leptin levels were correlated with the body mass index (BMI) as well as percent fat mass in stable COPD patients. The correlation coefficient tended to be weaker during exacerbation. A positive correlation between leptin and tumor necrosis factor (TNF)-α levels was found in COPD exacerbations, while it disappeared in patients with stable disease. Most studies indicated that circulating leptin levels in stable COPD patients were not significantly different from those in healthy controls when adjusted for gender and BMI, whilst leptin levels tended to elevate in exacerbation groups.

CONCLUSIONS

The normal regulatory mechanism of leptin is maintained in stable COPD patients despite weight loss. The additional correlation between leptin and TNF-α during exacerbations may support the closer association of leptin with changes in nutritional parameters and suggests its valuable role in the evaluation of systemic inflammatory responses in COPD patients during exacerbation, which merits further study.

Chronic obstructive pulmonary disease and comorbidities

Results of epidemiological studies have shown that chronic obstructive pulmonary disease (COPD) is frequently associated with comorbidities, the most serious and prevalent being cardiovascular disease, lung cancer, osteoporosis, muscle weakness, and cachexia. Mechanistically, environmental risk factors such as smoking, unhealthy diet, exacerbations, and physical inactivity or inherent factors such as genetic background and ageing contribute to this association. No convincing evidence has been provided to suggest that treatment of COPD would reduce comorbidities, although some indirect indications are available. Clear evidence that treatment of comorbidities improves COPD is also lacking, although observational studies would suggest such an effect for statins, β blockers, and angiotensin-converting enzyme blockers and receptor antagonists. Large-scale prospective studies are needed. Reduction of common risk factors seems to be the most powerful approach to reduce comorbidities. Whether reduction of so-called spill-over of local inflammation from the lungs or systemic inflammation with inhaled or systemic anti-inflammatory drugs, respectively, would also reduce COPD-related comorbidities is doubtful.

Circulatory and Adipose Tissue Leptin and Adiponectin in Relationship to Resting Energy Expenditure in Patients With Chronic Obstructive Pulmonary Disease

Increases in resting energy expenditure (REE) likely contribute to weight loss in various chronic diseases. In chronic obstructive pulmonary disease (COPD), relationships between the ventilatory impairment and increased REE, and between disturbances in adipokines and weight loss were previously described. Therefore, we investigated serum levels and adipose tissue expression of leptin and adiponectin, and their relationships to REE in patients with COPD. In 44 patients with stable COPD (38 male; age 62.3±7.2 years), REE was assessed using indirect calorimetry. Subcutaneous adipose tissue samples were analyzed using real-time PCR. From underweight [n=9; body mass index (BMI) <20.0 kg.m−2], to normal weight-overweight (n=24, BMI=20.0-29.9 kg.m−2) and obese patients (n=11; BMI≥30 kg.m−2), REE adjusted for body weight decreased (32.9±6.1 vs. 26.2±5.8 vs. 23.9±6.6 kcal.kg−1.24 h−1, p=0.006), serum levels and adipose tissue expression of leptin increased (p<0.001 for both), and serum and adipose tissue adiponectin decreased (p<0.001; p=0.004, respectively). REE was inversely related to serum and adipose tissue leptin (R=−0.547, p<0.001; R=−0.458, p=0.002), and directly to serum adiponectin (R=0.316, p=0.039). Underweight patients had increased REE compared to normal weight-overweight patients, in association with reductions in serum and adipose tissue leptin, and increased serum adiponectin, suggesting a role of adipokines in energy imbalance in COPD-related cachexia.

The National Emphysema Treatment Trial (NETT): Part I: Lessons learned about emphysema

The National Emphysema Treatment Trial (NETT) was a multicenter prospective randomized controlled trial that compared optimal medical treatment, including pulmonary rehabilitation, with optimal medical treatment plus lung volume reduction surgery (LVRS). It was the largest and most complete collection of patient demographic, clinical, physiological, and radiographic data ever compiled in severe emphysema. NETT investigated the effects of optimal medical management and LVRS on short- and long-term survival, as well as lung function, exercise performance, and quality of life. NETT also provided much information regarding the evaluation and prognosis of severe emphysema; specifically the important negative influences that hyperinflation and small airway disease have on survival. NETT emphasized the importance of addressing nonpulmonary issues such as nutrition, cardiac disease, anxiety, and depression in emphysema. NETT demonstrated that physiological, genomic, and radiographic phenotype can predict patient survival as well as response to treatment. Because the major purpose of NETT was to compare bilateral LVRS with optimal medical treatment in emphysema, patients enrolled into NETT were comprehensively characterized and selected to have a specific window of airflow obstruction and hyperinflation and to lack significant comorbidities. The NETT patient population’s restrictive features offer distinct advantages (well-characterized predominant emphysematous phenotype) and disadvantages (lack of comorbidities and significant chronic bronchitis) that must be considered when interpreting the implications of these results. Herein, we provide a summary of the major NETT findings that provide insight into the evaluation and medical treatment of emphysema.

Chronic obstructive pulmonary disease as an independent risk factor for cardiovascular morbidity

RATIONALE

Recent studies described association between chronic obstructive pulmonary disease (COPD) and increased risk of cardiovascular diseases (CVD). In their analysis none of these studies accounted for sociodemographic factors, health behaviors, and patient comorbidities simultaneously.

OBJECTIVE

To study whether COPD diagnosis is an independent risk factor for CVD.

METHODS

Subjects aged 40 years and older (N = 18,342) from the sample adult file of the 2002 National Health Interview Survey (NHIS) were included in the analysis. Chi-squared tests and odds ratios (OR) were utilized to compare the data. Multiple logistic regression was employed to analyze the association between COPD and CVD with simultaneous control for sociodemographic factors (age, gender, race, marital status, education, income), health behaviors (tobacco use, alcohol consumption, physical activity), and patient comorbidities (diabetes, hypertension, high cholesterol, and obesity). The analysis employed NHIS sampling weights to generate data representative of the entire US population.

RESULTS

The COPD population had increased prevalence of CVD (56.5% vs 25.6%; P < 0.0001). Adjusted logistic regression showed that COPD patients (N = 958) were at higher risk of having coronary heart disease (OR = 2.0, 95% CI: 1.5-2.5), angina (OR = 2.1, 95% CI: 1.6-2.7), myocardial infarction (OR = 2.2, 95% CI: 1.7-2.8), stroke (OR = 1.5, 95% CI: 1.1-2.1), congestive heart failure (OR = 3.9, 95% CI: 2.8-5.5), poor circulation in lower extremities (OR = 2.5, 95% CI: 2.0-3.0), and arrhythmia (OR = 2.4, 95% CI: 2.0-2.8). Overall, the presence of COPD increased the odds of having CVD by a factor of 2.7 (95% CI: 2.3-3.2).

CONCLUSIONS

These findings support the conclusion that COPD is an independent risk factor for CVD.

Patient adherence in COPD

Patient adherence to treatment in chronic obstructive pulmonary disease (COPD) is essential to optimise disease management. As with other chronic diseases, poor adherence is common and results in increased rates of morbidity, healthcare expenditures, hospitalisations and possibly mortality, as well as unnecessary escalation of therapy and reduced quality of life. Examples include overuse, underuse, and alteration of schedule and doses of medication, continued smoking and lack of exercise. Adherence is affected by patients' perception of their disease, type of treatment or medication, the quality of patient provider communication and the social environment. Patients are more likely to adhere to treatment when they believe it will improve disease management or control, or anticipate serious consequences related to non-adherence. Providers play a critical role in helping patients understand the nature of the disease, potential benefits of treatment, addressing concerns regarding potential adverse effects and events, and encouraging patients to develop self-management skills. For clinicians, it is important to explore patients' beliefs and concerns about the safety and benefits of the treatment, as many patients harbour unspoken fears. Complex regimens and polytherapy also contribute to suboptimal adherence. This review addresses adherence related issues in COPD, assesses current efforts to improve adherence and highlights opportunities to improve adherence for both providers and patients.

Nutritional aspects of chronic obstructive pulmonary disease

It is clear that being underweight is a poor prognostic sign in chronic obstructive pulmonary disease (COPD). It is also clear that undernutrition is at least in part associated with the severity of airflow obstruction. While both weight and body mass index are useful screening tools in the initial nutritional evaluation, fat-free mass (FFM) may be a better marker of undernutrition in patients with COPD. The causes of cachexia in patients with COPD are multifactorial and include decreased oral intake, the effect of increased work of breathing due to abnormal respiratory mechanics, and the effect of chronic systemic inflammation. Active nutritional supplementation in undernourished patients with COPD can lead to weight gain and improvements in respiratory muscle function and exercise performance. However, long-term effects of nutritional supplementation are not clear. In addition, the optimal type of nutritional supplementation needs to be explored further. The role of novel forms of treatment, such as androgens or appetite stimulants designed to increase FFM, also needs to be further studied. Thus, in the absence of definitive data, it cannot be said that long-term weight gain, either using enhanced caloric intake, with or without anabolic steroids or appetite stimulants, offers survival or other benefits to patients with COPD. However, there are indications from single-center trials that this is an avenue well worth exploring.

A prospective study of decline in fat free mass and skeletal muscle strength in chronic obstructive pulmonary disease

BACKGROUND

Skeletal muscle depletion is an important complication of chronic obstructive pulmonary disease (COPD) but little prospective data exists about the rate at which it occurs and the factors that promote its development. We therefore prospectively investigated the impact of disease severity, exacerbation frequency and treatment with corticosteroids on change in body composition and maximum isometric quadriceps strength (QMVC) over one year.

METHODS

64 patients with stable COPD (FEV1 mean (SD) 35.8(18.4) %predicted) were recruited from clinic and studied on two occasions one year apart. Fat free mass was determined using bioelectrical impedance analysis and a disease specific regression equation.

RESULTS

QMVC fell from 34.8(1.5) kg to 33.3(1.5) kg (p = 0.04). The decline in quadriceps strength was greatest in those with the highest strength at baseline (R -0.28 p = 0.02) and was not correlated with lung function, exacerbation frequency or steroid treatment. Decline in fat free mass was similarly higher in those with largest FFM at baseline (R = -0.31 p = 0.01) but was more strongly correlated with greater gas trapping (R = -0.4 p = 0.001). Patients with frequent exacerbations (>1 per year) (n = 36) experienced a greater decline in fat free mass compared to infrequent exacerbators (n = 28) -1.3(3.7)kg vs. +1.2(3.1)kg (p = 0.005), as did patients on maintenance oral steroids (n = 8) -2.8(3.3) kg vs. +0.2(3.5) kg (p = 0.024) whereas in those who stopped smoking (n = 7) fat free mass increased; +2.7(3.1) kg vs. -0.51(3.5) kg (p = 0.026).

CONCLUSION

Decline in fat free mass in COPD is associated with worse lung function, continued cigarette consumption and frequent exacerbations. Factors predicting progression of quadriceps weakness could not be identified from the present cohort.