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COPD: Determination of Energy Needs (2007)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To investigate the factors affecting body weight and dietary intake in a group of outpatients with COPD, and to investigate any differences between adequately nourished and malnourished patients.
Inclusion Criteria:
  • Patients with stable COPD
  • FEV1 < 80% predicted
  • FEV1/FVC ratio < 70%
Exclusion Criteria:
  • Subjects with confounding comorbidity such as malignancies, gastrointestinal disorders, thyroid function disorders
Description of Study Protocol:

Recruitment

Patients recruited consecutively from respiratory outpatient clinics at North Tyneside General Hospital.

Design

Cross-Sectional Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Not applicable.

Statistical Analysis

Two-tailed statistical tests were used in analysis.  Linear regression analysis used to investigate the possible determinants of BMI.  Subjects were split into adequately nourished and malnourished groups.  Subjects classified as malnourished if BMI < 20 and MAMC on or below the 15th centile.

Data Collection Summary:

Timing of Measurements

Measurements made as subjects were recruited.

Dependent Variables

  • Nutritional status assessed using BMI and upper arm anthropometry
  • Exercise tolerance measured using incremental shuttle walking test
  • Dietary intake based on 7-day food records, diet history with RD interview
  • Dietary problems through RD interview
  • Grip strength measured with dynamometer
  • Health-related quality of life measured with Chronic Respiratory Disease Questionnaire, SF-36 Health Survey and Hospital Anxiety and Depression Scale 

Independent Variables

  • Lung function measured through spirometry and diffusion capacity

Control Variables

  • Smoking status
Description of Actual Data Sample:

Initial N: 103 stable outpatients, 52.5% male

Attrition (final N):  103

Age:  mean age 68.6 years, range 40 - 87 years

Ethnicity: not mentioned

Other relevant demographics: 4% nonsmokers, 58% ex-smokers, 38% current smokers

Anthropometrics:

Location:  United Kingdom

 

Summary of Results:

 

  Adequately Nourished Malnourished Mean difference

P Value
Age (years) 67.4 +/- 8.8 72.5 +/- 6.7 5.0 <0.05

Amount smoked (pack-years)

41.2 +/- 22.7

63.2 +/- 28.0

 22.1

<0.05

FEV1 % predicted

41.7 +/- 12.5

35.9 +/- 11.6

 5.8

<0.05
DLCO % predicted 49.9 +/- 18.7 31.3 +/- 7.4 18.5 <0.05
DLCO/VA % predicted 58.3 +/- 20.5 41.5 +/- 10.7 16.8 <0.05
PEmax % predicted 55.2 +/- 18.9 39.6 +/- 15.4 15.6 <0.05
CRQ F 15.2 +/- 6 11.6 +/- 5.1 3.7 <0.05 
SF-36 RLP 20.2 +/- 33.7 6.3 +/- 21.2 13.9 <0.05
SF-36 EV 40.8 +/- 19.3 31.0 +/- 24.7 9.7 <0.05
SF-36 CIH 35.3 +/- 25.9 18.8 +/- 18.4 16.5 <0.05
HAD D 6.7 +/- 3.7 9.2 +/- 3.8 2.5 <0.05
Grip strength % predicted 78.5 +/- 19.4 59.7 +/- 22.9 18.8 <0.05
Daily energy intake (kJ) 8171 +/- 1883 7088 +/- 1854 1084 <0.05
Daily protein intake (g) 69.4 +/- 18.9 58.2 +/- 15.9 11.2 <0.05

Other Findings

23% were malnourished and malnourished subjects had lower lung function measurements, suffered more dietary problems and had lower nutritional intake than adequately nourished subjects.

Malnourished subjects also had poorer fatigue scores.

Current smokers were more likely to be malnourished, compared with ex- or non-smokers, who were more likely to be adequately nourished (Pearson's chi square 8.07, P = 0.007).

Factors that had the most effect on BMI were a low transfer factor, presence of early satiety, and being a current smoker.

Author Conclusion:
Important differences were found between adequately nourished and malnourished subjects.  These differences move us closer to understanding how best to screen and treat this group of patients.  This study only explained approximately 30% of the variation in BMI.  There is clearly a link between nutritional status and smoking, which should be further investigated.  Research is needed in this area to investigate what causes weight loss, how weight loss can be reversed, how at-risk patients can be identified early, and if treatment has any effect on morbidity and mortality.
Funding Source:
University/Hospital: Northern & Yorkshire Regional Research Training Fellowship
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.) N/A
  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? Yes
  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? Yes
  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? 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