COPD: Determination of Energy Needs (2007)

Citation:

Nguyen LT, Bedu M, Caillaud D, Beaufrere B, Beaujon G, Vasson M, Coudert J, Ritz P.  Increased resting energy expenditure is related to plasma TNF-alpha concentration in stable COPD patients.  Clin Nutr 1999;18(5):269-274. 

PubMed ID: 10601533
 
Study Design:
Cross-Sectional Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To assess the respective influences of the increased cost of breathing and of TNF-alpha plasma concentrations on the increased REE of clinically stable COPD patients.
Inclusion Criteria:
  • Non-inflammatory, non-malnourished, clinically stable, non-severely hypoxic COPD patients
  • All had COPD diagnosed according to criteria of American Thoracic Society
Exclusion Criteria:
  • Lung or any other cancer
  • Disease or treatment (except theophylline or beta-2 receptor agonists) that might affect energy metabolism or body composition (liver, kidney, or heart failure, diabetes mellitus, thyrotoxicosis, treatment with steroids or diuretics)
Description of Study Protocol:

Recruitment

Methods not described.

Design

Cross-Sectional Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Not applicable.

Statistical Analysis

Comparison of means performed with non-parametric tests.  Correlations between REE in % HB and TNF-alpha or respiratory parameters were sought using the rank correlation test of Spearman.  The least squares method was used for the REE-FFM relationship.  ANCOVA performed to address the potential effect of theophylline treatment or cigarette smoking on REE.

Data Collection Summary:

Timing of Measurements

REE, pulmonary function and plasma cytokine concentrations measured within 48 hours.

Dependent Variables

  • REE and gas exchange measured with indirect calorimetry and predicted with Harris-Benedict equation
  • Body weight, height, body composition measured with bioelectrical impedance
  • Pulmonary function:  vital capacity, FEV1, single-breath measurements of carbon monoxide transfer factor measured with pulmonary function analyzer, thoracic gas volume and mean respiratory airway resistance determined by barometric plethysmography
  • Blood samples analyzed for proinflammatory cytokines, TNF-alpha, interleukin 1-beta and 6, C-reactive protein, orosomucoid, albumin and transthyretin concentrations

Independent Variables

  •  COPD

Control Variables

  • Smoking
  • Theophylline
Description of Actual Data Sample:

Initial N: 36 patients, 30 men, 6 women

Attrition (final N):  36

Age:  mean age 60.5 +/- 8.9 years

Ethnicity:  not mentioned

Other relevant demographics:  BMI 23.6 +/- 4.3, 14 were still smokers

Anthropometrics:

Location:  France

 

Summary of Results:

Other Findings

REE was increased by 10 +/- 11% (P < 0.001) above predicted values.

Plasma TNF-alpha concentration was increased in all patients (mean value 26.3 +/- 14.3 pg/ml).

Excess REE (with respect to values predicted by Harris-Benedict equations) was correlated with plasma TNF-alpha concentration (P < 0.005), but not with the degree of airway obstruction, lung overinflation, or with oxygen cost of breathing.

Theophylline treatment resulted in a significant increase in REE by 15%. 

Author Conclusion:
In conclusion, the present study involved non-malnourished stable COPD patients and great care was taken to factor out acute inflammation or infection and resting hypoxia which could be seen to affect energy metabolism.  We showed that metabolic parameters (plasma TNF-alpha concentration and theophylline treatment) could determine the increased REE.  Since TNF-alpha also decreases energy intake, it is a good candidate to explain the energy imbalance observed in some COPD patients and strengthens the possibility that TNF-alpha antagonists could help to prevent an energy imbalance by matching energy intake to expenditure.
Funding Source:
Reviewer Comments:
Recruitment methods not described.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) N/A
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) N/A
 
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? Yes
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes