• Increase Font Size
  • Decrease Font Size
  • View as PDF

H/A: Body Composition Measurement (2009)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To compare REE in weight-stable and weight-losing patients with HIV infection and to discuss the relationship between abnormal body composition and REE in HIV-associated cachexia.
Inclusion Criteria:
  • Weight-losing patients were defined as having lost more than 3% of their weight during the four weeks before measurement
  • Weight-stable patients were defined as those without recent weight loss, independent of prior weight-loss episodes
  • Controls were weight stable, in good health and on a regular diet.
Exclusion Criteria:
  • Incomplete measurements
  • Voluntary diet for weight reduction.
Description of Study Protocol:

Recruitment

Patients from the HIV outpatient clinics and infectious disease wards at the University of Cologne. Controls were volunteers.

Design

Case-control study.

Statistical Analysis

  • Pearson's coefficient was used to determine correlations between measured and predicted REE
  • Differences between subgroups were tested with Mann-Whitney Wilcoxon U-test for continuous variables and Pearson's chi-square for dichotomous variables
  • Correlations between continuous variables were determined by Pearson's correlation coefficient.
Data Collection Summary:

Timing of Measurements

Measurements made on cases and controls and compared.

Dependent Variables

  • REE, measured by indirect calorimetry
  • Body composition, measured by bioelectrical impedance
  • Body temperature, frequency and consistency of bowel movements and food intake, recorded in one-week diary
  • Weight.

Independent Variables

  • HIV
  • Weight losing or weight stable.
Description of Actual Data Sample:
  • Initial N: 69 male HIV-infected patients and 29 male healthy controls
  • Attrition (final N): 65 cases, 28 with recent weight loss, 37 who were weight-stable and 29 controls. Four patients were excluded from the analysis.
  • Age
    • Healthy controls: 29±9 years
    • Weight-stable HIV patients: 41±8 years
    • Weight-losing HIV patients: 40±9 years.
  • Ethnicity: Not mentioned
  • Anthropometrics: Patients were significantly older than the control group
  • Location: Germany.
Summary of Results:

  Controls (N=29)

Weight-Stable (N=37)

Weight-Losing (N=28)
REE (kcal/day) 1,711±151 1,625±402 1,459±309

REE/kg BCM (kcal/kg/24 hr)

48.0±3.5

54.8±13.1

56.9±16.9

REE/kg body weight

23.85±2.0

24.0±5.2

23.9±6.2
REE vs Harris-Benedict (%) 98.3±7.7 101±21 95±21
REE vs Cunningham equation (%) 100.9±7.6 101±22 96±23

Other Findings

  • Absolute REE was lower in weight-losing patients than in controls (1,459±309 vs. 1,711±151kcal per day, P<0.001) and in weight-stable patients (1,625±402 kcal per day, P<0.05)
  • REE per kg body cell mass was higher in weight-losing and weight-stable patients than in controls (both P<0.01), due to lower body-cell mass in both patient groups (P<0.001)
  • REE (percentage Harris-Benedict) was not different among the three groups
  • Weight changes around the measurement were not correlated to REE (R2=0.0008, P=0.82)
  • REE was independent of diarrhea, acute infection, fever or caloric intake
  • REE had a stronger correlation to body weight and to Harris-Benedict's prediction than to fat-free mass or body cell mass
  • REE explains less than 1% of weight changes.
Author Conclusion:
  • In conclusion, our data on REE in weight-stable and in weight-losing patients cast doubt on the role of hypermetabolism in the pathogenesis of the HIV-wasting syndrome
  • Usual reference values for REE are not reliable in severely malnourished patients
  • Body cell mass measured by bioelectrical impedance is less reliable to predict normal REE than Harris-Benedict's equation
  • More research is needed about the energy consumption of viscera vs. muscle tissue in starvation and disease-related malnutrition
  • Some patients with reduced energy intake, malabsorption or diarrhea may fail to down-regulate REE, which is the normal response to starvation. But it is unlikely that hypermetabolism by itself is a major cause of weight loss in HIV-infected patients.
Funding Source:
University/Hospital: University of Cologne (Germany)
Reviewer Comments:
  • Controls not age-matched
  • Authors note that sample size may be too small to identify subgroups with relevant hypermetabolism and the fact that nutritional treatment was not standardized.
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? ???
  2.2. Were criteria applied equally to all study groups? ???
  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? ???
3. Were study groups comparable? No
  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? No
  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.) No
  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? Yes
  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.) Yes
  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? 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