COPD: Determination of Energy Needs (2007)

Citation:

Karakas S, Karadag F, Karul AB, Gurgey O, Gurel S, Guney E, Cildag O.  Circulating leptin and body composition in chronic obstructive pulmonary disease.  Int J Clin Pract 2005;59(10):1167-70.     

PubMed ID: 16178984
 
Study Design:
Case-Control Study
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To evaluate the association of circulating leptin levels and measures of body composition in COPD patients.
Inclusion Criteria:
  • Diagnosis of COPD established by respiratory physician based on American Thoracic Society guidelines
  • All patients receiving inhaled bronchodilator therapy
  • Patients not receiving nutritional support or inhaled/systemic corticosteroids
Exclusion Criteria:
Patients with disorders that affect weight maintenance (diabetes, thyroid dysfunction, alcoholism, malabsorption, renal, hepatic and neoplastic diseases) were excluded.
Description of Study Protocol:

Recruitment

Methods not specified.

Design

Case-Control Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Measurements of lung function, body composition and serum leptin.

Statistical Analysis

Correlations between parameters were evaluated using Pearson's rank correlation analysis.  Data of study groups were compared by Kruskal-Wallis test.

Data Collection Summary:

Timing of Measurements

Measurements made on patients and controls and compared.

Dependent Variables

  • Lung function measured through spirometry
  • Body composition measurements:  height, weight, circumference measurements, skinfold thicknesses, body fat with bioelectric impedance
  • Serum leptin concentration was measured by ELISA assay

Independent Variables

  • Presence of COPD

Control Variables

 

Description of Actual Data Sample:

Initial N: 30 COPD outpatients, 20 controls.  COPD patients grouped according to BMI.  Gender not mentioned.

Attrition (final N):  30 outpatients, 20 controls.

Age:  mean age patients:  66.3 +/- 8.4 years, mean age controls:  65.9 +/- 10.8 years 

Ethnicity:  not mentioned

Other relevant demographics:

Anthropometrics:  Demographics of subjects not described or compared.

Location:  Turkey

 

Summary of Results:

 

  BMI < 21 (n=14) BMI > 21 (n=16) Controls (n=20) P value

BMI

19.01 +/- 2.26

26.85 +/- 4.51 27.64 +/- 2.75 --

Weight (kg)

57.38 +/- 6.95

83.17 +/- 14.11

79.17 +/- 9.21

0.000

Body Fat %

18.82 +/- 6.17

33.02 +/- 2.09

27.9 +/- 3.70

0.001
Fat Mass 11.31 +/- 4.44 28.22 +/- 4.89 16.16 +/- 2.54 0.000
Fat Free Mass 47.20 +/- 4.31 54.70 +/- 9.06 56.46 +/- 7.41 0.019
Upper Mid-Arm Circumference (cm) 26.18 +/- 2.44 29.78 +/- 2.32 28.88 +/- 1.61 0.000
Waist Circumference (cm) 80.27 +/- 9.05 98.73 +/- 6.55 96.37 +/- 7.88 0.000
Triceps Skinfold Thickness (mm) 7.22 +/- 1.80 9.94 +/- 4.00 8.20 +/- 3.08 0.015
Biceps Skinfold Thickness (mm) 3.36 +/- 0.92 6.84 +/- 6.23 5.75 +/- 1.95 0.003
Leptin (ng/ml) 1.41 +/- 1.86 2.60 +/- 1.38 2.82 +/- 1.46 0.002

Other Findings

Mean BMI was 19.01 +/- 2.26 kg/m2 in group 1 (COPD patients with low BMI), 26.85 +/- 4.51 in group 2 COPD (COPD patients with normal/high BMI) and 27.64 +/- 2.75 kg/m2 in healthy controls (group 3).

Mean serum leptin concentration was 1.41 +/- 1.86 ng/ml in group 1, 2.60 +/- 1.38 ng/ml in group 2 and 2.82 +/- 1.46 ng/ml in group 3 (p = 0.002).

Leptin correlated to not only BMI but also body weight, waist circumference, triceps and biceps skinfold thickness and body fat percent (p < 0.05 for all). 

Author Conclusion:
In summary, this study was done to evaluate circulating leptin level and the association between leptin and measures of body composition in COPD patients.  We detected that serum leptin concentration was decreased in stable COPD patients with low BMI.  Leptin correlated not only with BMI but also body weight, waist circumference, triceps and biceps skinfold thickness and body fat percent.  As a conclusion, results of this study suggest that the cause of weight loss is not increased circulating leptin in COPD.  Instead, leptin remains regulated in COPD and further decreased in patients with low BMI, probably as a compensatory mechanism to preserve body fat content, which should be evaluated in further studies. 
Funding Source:
Reviewer Comments:
Recruitment methods and demographics of subjects not well described, difficult to know similarities between patients and controls.  Controls not divided by BMI.
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? No
  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) Yes
  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? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  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%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  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? 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? Yes
  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? N/A
  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)? N/A
  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