COPD: Effectiveness of Therapies (2007-2008)
- Patients with COPD participating in an inpatient pulmonary rehabilitation program
- Clinically stable condition
- Patients with signs of airway infection
- Cardiovascular, neurologic or endocrine diseases
- Locomotor limitations
- Resting arterial oxygen tension < 7.3 kPa
- Need for oxygen supplementation
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.
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
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
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.
Quality Criteria Checklist: Primary Research
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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 | |