COPD: Determination of Energy Needs (2007)

Citation:

Engelen MPKJ, Schols AMWJ, Lamers RJS, Wouters EFM.  Different patterns of chronic tissue wasting among patients with chronic obstructive pulmonary disease.  Clinical Nutrition 1999;18(5):275-280.

PubMed ID: 10601534
 
Study Design:
Case-Control Study
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To investigate possible differences in body composition between the COPD subtypes emphysema and chronic bronchitis, as defined by high-resolution computed tomography, adjusted for pulmonary function, as well as compare the body composition of the COPD subgroups to healthy age-matched volunteers. 
Inclusion Criteria:

COPD patients:

  • COPD according to the American Thoracic Society guidelines
  • Chronic airflow limitation defined as measured forced expiratory volume in one second (FEV1) less than 70% of predicted value
  • Irreversible obstructive airway disease (<10% improvement of FEV1 predicted baseline after inhalation of a beta-2-agonist
  • Clinically stable and not suffering from respiratory tract infection
  • No concomitant confounding diseases like malignancies, gastrointestinal disorders, severe endocrine disorders or recent surgery

Controls:

  • Healthy volunteers free from acute and chronic diseases
Exclusion Criteria:
Excluded if not included above.
Description of Study Protocol:

Recruitment

Patients consecutively admitted to a pulmonary rehab center.

Design

Case-Control Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Body weight and composition were assessed by DEXA.  Patients were stratified into chronic bronchitis and emphysema by high-resolution computed tomography.

Statistical Analysis

Patients stratified into 3 groups based on high-resolution computed tomography score and a second classification on body composition.  Differences in body composition and pulmonary function between all groups assessed by ANCOVA.

Data Collection Summary:

Timing of Measurements

Measurements made on patients and controls and compared.

Dependent Variables

  • Body weight measured through electronic beam scale  
  • Whole body FFM, lean mass, bone mineral content, and fat mass measured with DEXA and bone densitometer

Independent Variables

  • Presence and severity of emphysema evaluated by high-resolution computed tomography
  • Spirometry to determine forced expiratory volume in 1 second (FEV1)
  • Static and dynamic lung volumes assessed by whole-body plethysmography

Control Variables

  • FEV1
  • Sex
Description of Actual Data Sample:

Initial N: 99 severe COPD patients, 22 women, 77 men (50 with chronic bronchitis, 49 with emphysema), 28 healthy volunteers

Attrition (final N):  99 patients, 28 controls

Age:   mean age 64 years 

Ethnicity: not mentioned

Other relevant demographics:  FEV1: 38.5 +/- 13.3%

Anthropometrics:  Controls were age-matched.  Height did not differ between groups.

Location:  The Netherlands

 

Summary of Results:

Other Findings

COPD patients had lower values for FFM index (P < 0.001), due to a lower lean mass index (P < 0.001), and bone mineral content index (P < 0.001).   Bone mineral density was also lower in the COPD group (P < 0.001).

Lean mass depletion was found in 37% of the emphysema patients and in 12% of the chronic bronchitis patients.

The emphysema patients had lower values for body mass index than the other groups (P < 0.01), mainly due to a lower lean mass (P < 0.01) and bone mineral content (P < 0.01).  Bone mineral density was also lower in the emphysema group (P < 0.001).

Fat mass was also lower in the emphysema group compared to the chronic bronchitis group (P < 0.001).

Body weight, BMI, lean mass index and FFM index were not different between the chronic bronchitis and healthy controls.  The chronic bronchitis patients had a higher fat mass (P < 0.05) and a lower bone mineral content (P < 0.01) and bone mineral density (P < 0.001) than the healthy volunteers. 

Author Conclusion:
The present study shows substantial differences not only in body composition between COPD patients and healthy volunteers but also between the COPD subtypes chronic bronchitis and emphysema, stratified by high-resolution computed tomography.  These differences in wasting patterns need to be considered when initiating specific nutritional and exercise intervention strategies to enhance functional performance in COPD.
Funding Source:
Reviewer Comments:
Authors note that high-resolution computed tomography, despite being the most accurate imaging method for diagnosing emphysema, is not sensitive in detecting earliest lesions of emphysema.
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) Yes
  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) Yes
 
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? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  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.) Yes
  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? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  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? N/A
  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? N/A
  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? N/A
  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