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COPD: Effectiveness of Therapies (2007-2008)

Citation:

Vermeeren MA, Wouters EF, Nelissen LH, van Lier A, Hofman Z, Schols AM.  Acute effects of different nutritional supplements on symptoms and functional capacity in patients with chronic obstructive pulmonary disease.  Am J Clin Nutr 2001;73(2):295-301.

PubMed ID: 11157327
 
Study Design:
Randomized Crossover Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To investigate the acute effects of nutritional supplements on metabolism and exercise capacity in stable COPD patients.
Inclusion Criteria:
  • Patients with COPD participating in an inpatient pulmonary rehabilitation program
  • Clinically stable condition
Exclusion Criteria:
  • Patients with signs of airway infection
  • Cardiovascular, neurologic or endocrine diseases
  • Locomotor limitations
  • Resting arterial oxygen tension < 7.3 kPa
  • Need for oxygen supplementation
Description of Study Protocol:

Recruitment

Methods not described.

Design:  Randomized Crossover Trial 

Blinding used (if applicable):  Double-blind 

Intervention (if applicable)

  • Part 1:  effects of 3 different energy loads (placebo, 1046 kJ, and 2092 kJ, both 21% protein, 34 - 36% fat, 43 - 45% carbohydrate) were investigated in 14 COPD patients
  • Part 2:  effects of fat-rich (60% fat) compared with carbohydrate-rich (20% carbohydrate) supplement (both 1046 kJ) were investigated in 11 COPD patients

Statistical Analysis

For comparison between supplements, ANOVA was used.  If appropriate, corresponding baseline value was used as a covariate (ANCOVA).  In Part 1, if results were significantly different, a post hoc Tukey test was performed.  For comparison of baseline characteristics of subjects before each test, an independent Student's t test was used.

Data Collection Summary:

Timing of Measurements

Metabolic and ventilatory variables were measured postprandially and during a submaximal cycle endurance exercise test.

Dependent Variables

  • Pulmonary function:  flow-volume curves measured by flow screen, FEV1, inspiratory vital capacity, forced vital capacity, mean expiratory flow and peak expiratory flow calculated from flow-volume curve
  • Exercise testing through submaximal ergometer test
  • Symptoms:  shortness of breath, satiety and pain in legs measured using visual analog scale
  • Transcutaneous oxygen saturation measured with pulse oximeter
  • Metabolic and ventilatory variables measured in expired air using breathing mask
  • Heart rate
  • Venous blood samples to measure plasma lactate concentration

Independent Variables

  • Part 1:  effects of 3 different 200 ml energy loads (placebo, 1046 kJ, and 2092 kJ) were investigated in 14 COPD patients
  • Part 2:  effects of fat-rich compared with carbohydrate-rich 200 ml supplement (both 1046 kJ) were investigated in 11 COPD patients

Control Variables

 

Description of Actual Data Sample:

Initial N: 14 patients in Part 1 (10 men, 4 women), 11 patients in Part 2 (9 men, 2 women)

Attrition (final N):  as above

Age:  mean age Part 1 subjects:  65 +/- 11 years, mean age Part 2 subjects:  62 +/- 8 years 

Ethnicity:  not mentioned

Other relevant demographics:

Anthropometrics:  crossover trials, no subjects participated in both studies

Location:  The Netherlands

 

Summary of Results:

 Pulmonary function before and after supplementation in Part 2

 

CHO-rich Before

CHO-rich After

Fat-rich Before

Fat-rich After

FVC (L)

3.1 +/- 0.7 3.5 +/- 1.3 3.0 +/- 0.6 3.0 +/- 0.7

FEV1 (L)

1.1 +/- 0.3

1.1 +/- 0.4

1.0 +/- 0.4

1.0 +/- 0.4

Peak expiratory flow (L/s)

3.1 +/- 1.0

3.3 +/- 1.2, p < 0.05

3.1 +/- 0.9

3.1 +/- 0.9

Other Findings

Part 1:

There were no immediate negative effects of the supplement; a slight but significant postprandial increase in RQ was found after the 1046 kJ and 2092 kJ supplements compared to placebo (0.87 +/- 0.05, 0.89 +/- 0.05 and 0.84 +/- 0.04, respectively).

Relative to the 1046 kJ supplement, the metabolic and ventilatory responses were significantly higher after the 2092 kJ supplement, but these differences were eliminated during exercise. 

Part 2:

There was no significant difference in metabolism or exercise capacity after a fat-rich or carbohydrate-rich supplement.

The change in shortness of breath (postprandial compared with preprandial) was significantly greater after the fat-rich supplement.

Author Conclusion:
In conclusion, a liquid oral nutritional supplement with an energy content of 1046 kJ is preferable to an energy load of 2092 kJ because after the smaller load there was a better metabolic and ventilatory response and less satiety.  Also, the carbohydrate-rich supplement was preferable to the fat-rich supplement because lung function increased and there was less shortness of breath.
Funding Source:
Reviewer Comments:
Small sample sizes, power calculations not done.  Recruitment methods not described.  1 meal trials.
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? ???
  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? 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? Yes
  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? 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? Yes
  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? 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? N/A
  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? ???
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
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