COPD: Determination of Energy Needs (2007)
- Acute exacerbation defined as a recent increase in dyspnea, cough, and sputum production of sufficient severity to warrant hospital admission; presence of exacerbation determined by independent chest physician
- COPD defined according to American Thoracic Society criteria
Cases:
- Suffering from concomitant diseases
- Stay in hospital less than 7 days
Controls:
- Not exhibiting any acute or chronic disease
- Not taking medication influencing energy or glucose metabolism
Recruitment
Subjects consecutively admitted to the hospital suffering from an acute exacerbation of COPD.
Design
Case-Control Study.
Blinding used (if applicable)
Not applicable.
Intervention (if applicable)
Patients received bronchodilating medication 2-3 hours before measurements started.
Statistical Analysis
Paired t test used for comparisons across days with Bonferroni correction. Differences between cases and controls on Days 1 and 7 compared using Student's t test for independent samples and Mann-Whitney U test. Plasma leptin was logarithmically transformed. Pearson's product-moment correlation coefficients calculated on Days 1 and 7. Linear stepwise regression performed to investigate which factor could explain variation in dietary intake/REE ratio.
Timing of Measurements
Measurements performed in early morning after 10 hour fast. Measurements done at Days 1, 3, 5 and 7 after hospitalization.
Dependent Variables
- FEV1, inspiratory vital capacity and peak expiratory flow calculated from flow-volume curve using spirometry
- Arterial oxygen and carbon dioxide tension analyzed on blood gas analyzer
- Body height, weight
- Body composition measured through bioelectrical impedance analysis
- Habitual dietary intake evaluated using diet history method with cross check
- Resting energy expenditure measured by indirect calorimetry
- Blood samples analyzed for glucose, insulin, inflammatory parameters, leptin
Independent Variables
- COPD or healthy
Control Variables
- Sex
- Age
- Percentage fat mass
Initial N: 17 subjects, 11 men, 6 women. 23 healthy controls, 16 men, 7 women
Attrition (final N): 17 cases, 23 controls
Age: mean age 66 +/- 10 years
Ethnicity: not mentioned
Other relevant demographics:
Anthropometrics: Healthy elderly control subjects not well described.
Location: The Netherlands
Correlation Analysis - Leptin and Glucose Metabolism on Day 7 of COPD Acute Exacerbation
|
Natural Logarithm of Leptin | Glucose |
Insulin |
Fat Mass, % Body Weight |
r = 0.73, p = 0.10 |
r = 0.71, p = 0.022 |
NS |
Glucose |
NS |
-- |
NS |
Insulin | NS | NS | -- |
Soluble TNF receptor 55 | r = 0.65, p = 0.041 | r = 0.81. p = 0.015 | NS |
Soluble TNF receptor 75 |
NS |
NS |
NS |
Other Findings
On admission, the dietary intake/REE ratio was severely depressed (1.28 +/- 0.57) but gradually restored until Day 7 (1.65 +/- 0.45, p = 0.005 versus Day 1).
Glucose and insulin concentrations were elevated on admission, but on Day 7 only plasma glucose was decreased.
The sTNF-Rs were not different from healthy subjects and did not change.
Plasma leptin, adjusted for fat mass expressed as percentage of body weight, was elevated on Day 1 compared with healthy subjects (1.82 +/- 3.85 versus 0.32 +/- 0.72 ng%/ml, p = 0.008), but decreased significantly until Day 7 (1.46 +/- 3.77 ng%/ml, p = 0.015 versus Day 1).
On Day 7, sTNF-R55 was, independently of % fat mass, correlated with the natural logarithm of leptin (r = 0.65, p = 0.041) and with plasma glucose (r = 0.81, p = 0.015).
In addition, the dietary intake/REE ratio was not only inversely related with the natural log of leptin (-0.74, p = 0.037), but also with sTNF-R55 (r = -0.93, p = 0.001) on Day 7.
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) | 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? | ??? | |
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? | ??? | |
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.) | ??? | |
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.) | N/A | |
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? | 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? | Yes | |
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? | 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? | ??? | |
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 | |