COPD: Effectiveness of Therapies (2007-2008)

Citation:

Ferreira IM, Brooks D, Lacasse Y, Goldstein RS, White J.  Nutritional supplementation for stable chronic obstructive pulmonary disease.  Cochrane Database Syst Rev 2005 Apr 18;(2):CD000998.

PubMed ID: 15846608
 
Study Design:
Meta-analysis or Systematic Review
Class:
M - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
  • To conduct a systematic review of randomized controlled trials to clarify whether nutritional supplementation (caloric supplementation for at least 2 weeks) improved anthropometric measures, pulmonary function, respiratory muscle strength and functional exercise capacity in patients with stable COPD
  • To assess the effect of nutritional support on anthropometric measures, pulmonary function tests, respiratory and peripheral muscle strength and/or endurance, functional exercise capacity and health related quality of life in patients with COPD
  • If benefit is demonstrated, perform subgroup analysis to identify treatment regimes and patient populations that demonstrate greatest benefits
Inclusion Criteria:
  • Only randomized controlled trials
  • Trials must have included stable patients among whom at least 75% had COPD characterized by a FEV1 less than 70% and less than 15% reversibility after bronchodilator
  • Subjects received oral, enteral or parenteral nutritional support versus placebo or versus their usual diet or other treatment regimens such as anabolic substances
  • Nutritional support was defined as any caloric supplementation given for more than 2 weeks

 

Exclusion Criteria:
  • Studies involving patients with COPD undergoing treatment in the intensive care unit were excluded
  • Studies assessing the efficacy of anabolic substances alone
  • Full publications of studies previously excluded
  • Inadequate interventions
  • Participants not considered in the review
  • Ongoing studies
  • Lack of adequate data
  • Awaiting translation
Description of Study Protocol:

Recruitment

Randomized controlled trials were identified from the Cochrane Airways Group register of randomized controlled trials, a hand-search of abstracts presented at international meetings and consultation with experts.  Searches were current as of 2005.  Terms included Nutrit*, Malnutrit*, Undernourish*, Weight Loss, Food, Feed, Diet*, Lean body mass, Body Mass Index, Depletion, Anabolic, Androgen, Male hormone, Sex hormone, Growth hormone. 

Design:  Systematic Review 

Blinding used (if applicable):  2 were double blinded. 

Intervention (if applicable): 

Two reviewers independently selected the trials for inclusion, assessed quality and extracted the data.

Statistical Analysis

Within each trial and for each outcome, effect sizes were calculated.  Effect sizes were then pooled by a random effects model.  Homogeneity among the effect sizes was also tested.

Data Collection Summary:

Timing of Measurements

Not applicable.

Dependent Variables

  • Anthropometric (body weight, lean body mass, body mass index) and functional exercise (timed walk test, submaximal or graded exercise)
  • Pulmonary mechanics (lung volumes, respiratory muscle function), peripheral muscle function and health related quality of life

Independent Variables

  • Nutritional support for more than 2 weeks

Control Variables

 

Description of Actual Data Sample:

Initial N:  44 studies originally identified.

Attrition (final N):  12 studies recruiting 392 participants met the inclusion criteria. 

Age:  not mentioned

Ethnicity: not mentioned

Other relevant demographics:

Anthropometrics:

Location:  worldwide publications

 

Summary of Results:

Other Findings

Of 12 studies, 8 were considered high quality, 4 of lesser quality and 2 studied were double blinded.

For each of the outcomes studied, the effect of nutritional support was small:  the 95% confidence intervals around the pooled effect sizes all included 0.

The effect of nutritional support was homogeneous across studies (P value for the Chi-square test for heterogeneity ranged from 0.19 to 1.00).

Changes in the 6-minute walk test did not exceed the minimum clinically important difference, defined as the smallest distance perceived as important by the average patient.

When data were collected as change from baseline rather than absolute scores, there were no statistically significant differences between supplementation or control in terms of fat mass, fat free mass and lean mass.

Triceps skinfold thickness was increased by a non-significant amount in all studies and the pooled SMD was at the threshold of statistical significance, which would suggest that some fat was deposited in the patients receiving nutritional supplementation but this change does not constitute a worthwhile response to therapy apart from cosmetic benefits.

Author Conclusion:
Nutritional support had no significant effect on anthropometric measures, lung function or exercise capacity in patients with stable COPD.  There is no evidence from this analysis that simple nutritional supplementation confers benefit to patients with COPD in terms of clinical outcomes such as lung function or health-related quality of life, when nutritional supplementation is given as part of a multi-disciplinary rehabilitation programme including exercise therapy.  The data on weight gain did not suggest an overall significant effect of a nutritional supplement.  In participants who are undernourished the findings of the review are mixed.  The change from baseline data indicate that there is significant impact between weight gain, reduced functional impairment and quality of life.
Funding Source:
Reviewer Comments:
Authors note that meta-analysis would have been given greater statistical power with a larger number of subjects.
Quality Criteria Checklist: Review Articles
Relevance Questions
  1. Will the answer if true, have a direct bearing on the health of patients? Yes
  2. Is the outcome or topic something that patients/clients/population groups would care about? Yes
  3. Is the problem addressed in the review one that is relevant to dietetics practice? Yes
  4. Will the information, if true, require a change in practice? Yes
 
Validity Questions
  1. Was the question for the review clearly focused and appropriate? Yes
  2. Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described? Yes
  3. Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased? Yes
  4. Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methodsspecified,appropriate, andreproducible? Yes
  5. Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined? Yes
  6. Was the outcome of interest clearly indicated? Were other potential harms and benefits considered? Yes
  7. Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently acrossstudies and groups? Was thereappropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described? Yes
  8. Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels ofsignificance and/or confidence intervals included? Yes
  9. Are conclusions supported by results with biases and limitations taken into consideration? Are limitations ofthe review identified anddiscussed? Yes
  10. Was bias due to the review's funding or sponsorship unlikely? Yes