COPD: Determination of Energy Needs (2007)

Citation:

Baarends EM, Schols AM, Westerterp KR, Wouters EF.  Total daily energy expenditure relative to resting energy expenditure in clinically stable patients with COPD.  Thorax 1997;52(9):780-5.

PubMed ID: 9371208
 
Study Design:
Cross-Sectional Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To investigate whether an increased REE in clinically stable patients with COPD is directly related to an increased total daily energy expenditure in free living conditions.
Inclusion Criteria:
  • Moderate to severe COPD in a stable clinical condition, diagnosis made according to criteria of American Thoracic Society
Exclusion Criteria:
  • Patients with arterial oxygen pressure of <7.3 kPa
  • Patients suffering from cancer, unstable cardiac condition, active GI abnormalities, recent surgery, severe endocrine disorders, locomotor diseases
Description of Study Protocol:

Recruitment

Patients admitted to pulmonary rehab center for period of 8 - 10 weeks but allowed to go home on weekends.

Design

Cross-Sectional Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Not applicable.

Statistical Analysis

A linear regression equation between REE and FFM was developed based on the 20 patients studied and used to determine hypermetabolism/normometabolism.  Mann-Whitney U test was used to compare values between groups.  Correlation coefficients and multiple regression analysis was used to test the linear relationship between variables.  Bonferroni correction was used when appropriate.

Data Collection Summary:

Timing of Measurements

Total daily energy expenditure measured over 2 week interval.  REE measured at least twice, before and during the doubly labelled water method.

Dependent Variables

  • Total daily energy expenditure measured using doubly labeled water
  • Body height, weight, BMI
  • Fat free mass calculated from total body water assessed by deuterium dilution
  • Resting energy expenditure measured by indirect calorimetry
  • Lung function tests:  FVC, FEV1, total lung capacity, intrathoracic gas volume, carbon monoxide transfer factor, blood gases
  • 14 day dietary intake, nutritionally analyzed
  • Physical activity program

Independent Variables

  • COPD

Control Variables

 

Description of Actual Data Sample:

Initial N: 20 subjects with COPD, 19 men, 1 woman

Attrition (final N):  20

Age:  mean age increased REE:  65 years, normal REE:  69 years

Ethnicity:  not mentioned

Other relevant demographics:

Anthropometrics:  There were no significant differences between normometabolic and hypermetabolic patients in terms of age, body composition, lung function, or use of medications affecting energy expenditure.

Location:  The Netherlands

 

Summary of Results:

 

  Increased REE (n=10) Normal REE (n=10)

p value

REE (kcal/24 h) 1631 (1423 - 2112) 1426 (1212 - 1802) <0.05

REE (% HB)

125 (104 - 135)

107 (90 - 113)

<0.01

TDE (kcal/24 h)

2593 (2127 - 3083)

2629 (2032 - 3179)

NS

TDE (TDE/REE) 1.56 (1.31 - 1.87) 1.78 (1.53 - 2.03) <0.025
Energy - Activities (kcal/24 h) 680 (288 - 1129) 882 (503 - 1190) 0.028
Calories (kcal/24 h) 2070 (1761 - 2602) 2123 (1604 - 2423) NS
% Protein 16 (14 - 21) 16 (14 - 20) NS
% Carbohydrate 46 (40 - 50) 44 (38 - 45) <0.017
% Fat 38 (32 - 45) 40 (34 - 47) NS

Other Findings

REE correlated significantly with FFM (r = 0.73, p < 0.001), and total daily energy expenditure also correlated significantly with FFM (r = 0.70, p < 0.01).

10 men with a significantly higher REE than those with a normal REE (median difference 205 kcal/24 hours, p < 0.05) had a comparable total daily energy expenditure (hypermetabolic at rest, median 2593, range 2127 - 3083 kcal/24 hours; normometabolic at rest, median 2629, range 2032 - 3179 kcal/24 hours).

There was no difference in mean daily heart rate between the groups (hypermetabolic at rest:  median 92, range 82 - 98; normometabolic at rest:   median 98, range 75 - 116 beats/min) or in the variation in the heart rate during the day.

By means of multiple regression analysis, it was shown that REE did not correlate significantly with total daily energy expenditure when fat free mass was taken into account. 

Author Conclusion:
The results of our study suggest that total daily energy expenditure is increased in clinically stable patients with COPD, but that the causes are probably not directly related to the suggested mechanisms for an increased REE in patients with COPD.  The cause for an increased energy expenditure for activities (total daily energy expenditure) in patients with COPD is as yet unknown, but the present study warrants further investigation of the energy expenditure for standardized activities.
Funding Source:
Reviewer Comments:
Sample composed of almost all men.  Did not address thermic effect of food - assumed at 10%.  Authors note that food intake underreported.  Measurements not taken at the same time.  Definition of normometabolism/hypermetabolism based on regression equation of these 20 patients.
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? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) No
  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? ???
  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