COPD: Determination of Energy Needs (2007)

Citation:

Schols AM, Buurman WA, Staal van den Brekel AJ, Dentener MA, Wouters EF.  Evidence for a relation between metabolic derangements and increased levels of inflammatory mediators in a subgroup of patients with chronic obstructive pulmonary disease.  Thorax 1996;51(8):819-24.

PubMed ID: 8795671
 
Study Design:
Case-Control Study
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To assess the relationship between REE, acute phase proteins, and inflammatory mediators in patients with COPD.
Inclusion Criteria:

Cases:

  • Moderate to severe COPD, FEV1 of 37 +/- 15% predicted

Controls:

  • Aged over 50 years
  • Mean FEV1 of 112 +/- 16% predicted
Exclusion Criteria:

Cases:

  • Patients with increase in FEV1 of more than 10% of predicted after administration of bronchodilator
  • With unstable COPD

Controls:

  • No evidence of COPD based on questionnaires and lung function testing
Description of Study Protocol:

Recruitment

Patients consecutively admitted to an inpatient pulmonary rehab centre in stable clinical condition.  Controls were part of a random population sample of subjects living in same area as patients.

Design

Case-Control Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Not applicable.

Statistical Analysis

Groups compared by ANOVA or Mann-Whitney U test where appropriate.  Chi-squared test used to compare categorical variables.

Data Collection Summary:

Timing of Measurements

Measurements made and compared between groups.

Dependent Variables

  • Resting energy expenditure measured by indirect calorimetry
  • Fat free mass measured by bioelectrical impedance
  • Tumor necrosis factor alpha, soluble tumor necrosis receptors 55 and 75 (sTNF-R55, sTNF-R75), interleukin-6 and interleukin-8, CRP and lipopolysaccharide binding protein (LBP) were measured by ELISA
  • Lung function testing included spirometry, transfer factor, thoracic gas volumes, and airway resistance

Independent Variables

  • COPD or healthy

Control Variables

 

Description of Actual Data Sample:

Initial N: 30 patients, 26 healthy controls

Attrition (final N):  30 patients, 26 controls

Age:  mean age patients:  61 +/- 6 years, controls:  59 +/- 5 years

Ethnicity:  not mentioned

Other relevant demographics:

Anthropometrics:  Controls were age-matched but not gender matched

Location:  The Netherlands

 

Summary of Results:

 

 

Patients (n=30) Controls (n=26)

p value

M:F

23:7

13:13

--

BMI

23.5 +/- 4.2

27.0 +/- 2.5

<0.001

FFM (kg)

47.7 +/- 2.2

49.5 +/- 7.6

NS

Fat mass (kg) 17.8 +/- 7.0 25.5 +/- 5.3 <0.001
sTNF-R55 (ng/ml) 1.4 +/- 0.8 1.0 +/- 0.3  NS
sTNF-R75 (ng/ml) 1.7 +/- 1.0 1.1 +/- 0.4 <0.05
IL-8 (pg/ml) 140 +/- 230 <20 <0.001
CRP (ug/ml) 64.3 +/- 79.9 <5 <0.01
LBP (ug/ml) 13.2 +/- 7.7 8.6 +/- 3.1 <0.001

Other Findings

14 patients had a normal REE and in 16 it was raised.

The mean BMI and fat mass were significantly lower in the latter but pulmonary function data were similar in the 2 groups.

BMI was significantly higher in healthy subjects.

Author Conclusion:
A subset of patients with COPD with an increased REE and decreased FFM have increased levels of acute phase reactant proteins and inflammatory cytokines in their serum; these phenomena may be causally related.
Funding Source:
Reviewer Comments:
Controls were age-matched but not gender matched, body composition not adjusted for gender.  No power calculations done.
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? ???
  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? ???
3. Were study groups comparable? ???
  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? ???
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  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.) ???
  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? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? Yes
  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? Yes
  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? ???
  8.1. Were statistical analyses adequately described and the results reported appropriately? ???
  8.2. Were correct statistical tests used and assumptions of test not violated? ???
  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? No
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