COPD: Determination of Energy Needs (2007)

Citation:

De Benedetto F, Del Ponte A, Marinari S, Spacone A.  In COPD patients, body weight excess can mask lean tissue depletion:  a simple method of estimation.  Monaldi Arch Chest Dis 2000;55(4):273-8.

PubMed ID: 11057077
 
Study Design:
Case-Control Study
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To find parameters that take into consideration the fact that body composition should be taken into account instead of weight only, and to assess whether COPD can be considered a "protein wasting disease", defining sensitive and significant indices of lean tissue depletion in relationship to the severity of the clinical symptoms.
Inclusion Criteria:

Cases:

  • Outpatients with differing degrees of COPD according to the ERS Guidelines classification
  • All had been diagnosed for at least 10 years from their patient history, physical examinations, chest radiographs, and respiratory function testing
  • Stable phase of disease
  • All were free from diabetes, kidney, heart and liver disease, or any other causes of undetectable edema
  • Were not regular users of diuretics
  • All use of medicines were interrupted 2 days before the study

Controls:

  • Apparently healthy subjects
  • No history of pulmonary disease and normal respiratory function tests
Exclusion Criteria:
Excluded if not included above.
Description of Study Protocol:

Recruitment

Outpatients consecutively recruited from the outpatients department and then observed at the Pulmonary Ward of the City General Hospital.

Design

Case-Control Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Not applicable.

Statistical Analysis

All subjects evaluated according to BMI:  underweight (<20), normal weight (20-26), overweight (>26).  COPD patients also divided according to phA:  malnourished (<5) and normal (>5).  Statistical analysis with Student's t test was used.  The comparison of various parameters of phA was performed after the logarithmic transformation of angular values.  A simple correlation coefficient was used to assess the association between variables.

Data Collection Summary:

Timing of Measurements

Anthropometric measurements and body composition analysis carried out and compared between outpatients and controls.

Dependent Variables

  • Body weight, height and BMI
  • Body composition measurements completed through bioelectrical impedance analysis

Independent Variables

  • Severity of COPD as measured by pulmonary function tests and arterial blood gases

Control Variables

 

Description of Actual Data Sample:

Initial N: 175 stable COPD outpatients (145 males, 30 females), 60 healthy controls (45 males, 15 females)

Attrition (final N):  175 outpatients, 60 controls

Age:  COPD outpatients mean age 69.2 +/- 7.98 years, controls mean age 65.3 +/- 13.3 years

Ethnicity:  not mentioned

Other relevant demographics:

Anthropometrics:  Controls were matched for sex, age and anthropometric parameters.

Location: Italy

 

Summary of Results:

 

Subjects BMI - All subjects Underweight subjects (BMI < 20) phA - All subjects Malnourished subjects (phA <5)
COPD (n=175) 26.5 +/- 4.7 18.21 +/- 1.42 5.93 +/- 1.14 4.32 +/- 0.53

Controls (n=60)

26.4 +/- 4.52

19.54 +/- 0.22

6.36 +/- 1.27

4.27 +/- 1.21

Parameter phA < 5 phA > 5 p Value
Subjects - n (%) 33 (18.8) 142 (81.2)  
Age (years) 73.0 +/- 6.3 68.4 +/- 8.1 <0.002

PaO2 (mmHg)

59.4 +/- 10.4

67.3 +/- 11.4

<0.000

PaCO2 (mmHg) 46.8 +/- 8.1 42.9 +/- 6.9 <0.005
SaO2 (%) 89.3 +/- 4.8 91.8 +/- 4.3 <0.003
FEV1 (% predicted) 40.3 +/- 12.2 50.3 +/- 15.8 <0.000
BCM (% BW) 29.3 +/- 6.5 36.5 +/- 4.8 <0.000
Na/K 1.26 +/- 0.19 0.93 +/- 0.14 <0.000
FM (% BW) 29.1 +/- 13.0 29.0 +/- 8.3 NS 

FFM (% BW)

70.9 +/- 13.0

71.0 +/- 8.3

NS

Other Findings

The data obtained showed a lower prevalence (9%) of underweight COPD patients in comparison with normal weight (37%) and overweight (54%) patients.

In COPD patients, the phase angle measured by bioelectrical impedance analysis, whose deterioration is a good indicator of protein mass depletion, was altered by 19%, thus allowing the identification of currently malnourished subjects included in the overweight COPD patients group.

In addition, significant correlations (p = 0.000) were found between the same nutritional variable, respiratory function, and gas-exchange parameters, thus confirming that the more severe the stage of the pulmonary disease, the higher the degree of protein breakdown, regardless of body weight. 

Author Conclusion:
In conclusion, the bioelectrical impedance analysis approach for COPD patients in clinical practice could be useful because the phA parameter is more sensitive in the illustration of the nutritional conditions of these subjects, regardless of body weight, and is significantly related to gas-exchange abnormalities.  It is due to this greater sensitivity that the better correlation between the poor nutritional status and the severity of the pulmonary disease occurs.
Funding Source:
University/Hospital: General Hospital Chieti (Italy)
Reviewer Comments:
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? Yes
  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? Yes
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) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  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.) Yes
  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? N/A
  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? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  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? N/A
  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? N/A
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