• Increase Font Size
  • Decrease Font Size
  • View as PDF

COPD: Determination of Energy Needs (2007)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To determine the role of diet-induced thermogenesis in the development of malnutrition in patients with COPD.
Inclusion Criteria:
  • FEV1/VC <55% and <70% of predicted values, with a reversibility of <10% of predicted FEV1 after inhalation of salbutamol
  • In stable pulmonary and cardiac condition (over 2 months since the last respiratory exacerbation, bronchopulmonary infection, or right ventricular failure)
  • Available data for resting and postprandial energy expenditure measurements
  • Comprehensive assessment of nutritional status
Exclusion Criteria:
  • Patients with restrictive functional pattern defined by a total lung capacity < 90% of predicted value
  • Those with diffuse bronchiectasis, active GI abnormalities, cancer, severe endocrine disorders, or history of recent surgery
Description of Study Protocol:

Recruitment

All male patients with COPD investigated between June 1991 and June 1995 who fulfilled inclusion criteria.

Design

Retrospective Cohort.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Metabolic measurements in fasting state and after consumption of mixed test meal.

Statistical Analysis

ANOVA with repeated measures used for unpaired continuous data and the chi-square test with Yate's correction for categorical variables.  Step by step linear regression analysis was used to assess associations between nutritional, functional and metabolic parameters.  Correlation coefficients obtained by Spearman's rank method.

Data Collection Summary:

Timing of Measurements

Diet-induced thermogenesis determined by comparing postprandial energy expenditure and REE.

Dependent Variables

  • Body height, weight, BMI, frame size, mid-upper arm circumference, mid-arm muscle circumference
  • Fat mass estimated from the sum of skinfold thicknesses at 4 sites:  bicipital, tricipital, subscapular and suprailiac
  • Fat free mass estimated by bioelectrical impedance
  • Diet-induced thermogenesis measured over 4 hours after consumption of meal
  • REE measured by indirect calorimetry after an overnight fast
  • Pulmonary function tests:  FEV1 and FVC measured by a heated pneumotachograph or with wet spirometer, lung volumes assessed by helium dilution technique, blood gases measured with analyzer

Independent Variables

  • Mixed test meal of 0.4 x REE load, 1.35 kcal/ml, 55% CHO, 20% fat, 25% protein
  • Dietary intake estimated with diet history method and RD interview

Control Variables

  • Theophylline levels measured with fluorescence polarization immunoassay
Description of Actual Data Sample:

Initial N: 26 patients with stable COPD, all male

Attrition (final N):  26 males

Age:  mean age malnourished:  63.6 +/- 3.5 years, normally nourished:  57.2 +/- 3.1 years

Ethnicity:  not mentioned 

Other relevant demographics: 

Anthropometrics:

Location: France

 

Summary of Results:

 

  Malnourished (n=10) Normally Nourished (n=16)

p Value
Energy intake (kcal/24 hrs) 2429 +/- 217 2163 +/- 107 NS

Energy intake/weight(kcal/kg)

40.3 +/- 3.8

31.8 +/- 2.4

<0.05

Energy intake/FFM (kcal/kg)

52.6 +/- 4.9

41.2 +/- 2.6

<0.05
Energy intake/active cell mass (kcal/kg) 86.2 +/- 11.2 64.3 +/- 4.8 <0.05
Energy intake/REE (%) 149.6 +/- 12.1 126.0 +/- 7.6 NS
REE (kcal/24 hrs) 1622 +/- 71 1756 +/- 54 NS
REE/BMR (%) 125.0 +/- 4.4 116.5 +/- 2.9 NS
REE/weight (kcal/24 hours/kg) 28.7 +/- 1.2 25.8 +/- 0.6 <0.02
REE/BMI (kcal/24 hrs/kg/m2) 83.3 +/- 3.9 75.0 +/- 2.3 <0.02
REE/FFM (kcal/24 hrs/kg) 38.2 +/- 1.8 33.9 +/- 0.8 <0.01
REE/active cell mass (kcal/24 hrs/kg) 65.1 +/- 4.7 53.0 +/- 1.3 <0.05
REE (kcal/min) 1.12 +/- 0.05 1.22 +/- 0.04 NS
Load (kcal) 579 +/- 28 686 +/- 27 <0.02
Load/weight (kcal/kg) 10.5 +/- 0.8 10.0 +/- 0.3 NS
post EE (kcal/min) 1.44 +/- 0.05 1.53 +/- 0.05 NS
change in EE (kcal/min) 0.32 +/- 0.02 0.31 +/- 0.03 NS
Change in EE/REE (%) 28.0 +/- 1.3 25.4 +/- 2.1 NS
DIT/load (%) 13.4 +/- 1.1 10.9 +/- 0.8 NS

Other Findings

10 patients were undernourished (weight < 90% IBW and/or FFM < 69% IBW) and 16 were normally nourished.

The REE for the entire group was 119.8 +/- 2.5% of predicted BMR with no significant difference between malnourished and eutrophic patients.

No statistical difference in diet-induced thermogenesis was found between undernourished and eutrophic patients.

There was no relationship between diet induced thermogenesis and nutritional or functional parameters, notably FFM.

Author Conclusion:
In conclusion, our results do not support the role of increased diet-induced thermogenesis in the development of malnutrition in patients with COPD but confirm that malnutrition is associated with an increased resting energy expenditure in those patients.  The mechanisms of this resting hypermetabolism are not yet fully understood.
Funding Source:
Reviewer Comments:
Only males studied - body composition is different in women.  Authors note that thermogenic effect of mixed meal may last 6 hours or longer, yet it was only measured over 4 hour period.  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? 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? Yes
  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? ???
  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? ???
  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? Yes
  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? ???
  7.1. Were primary and secondary endpoints described and relevant to the question? ???
  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? ???
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? ???
  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? 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