H/A: Body Composition Measurement (2009)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To define the regional body composition changes in HIV-positive patients reporting truncal enlargement.

Inclusion Criteria:

None specifically mentioned.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

HIV-infected patients and healthy control subjects were recruited for separate investigations in the study, but all had the same body composition studies.

Design

Case-control study.

Intervention

Whole-body and regional skeletal muscle and adipose tissue contents were measured by magnetic resonance imaging and dual-energy x-ray absorptiometry and compared in HIV-infected patients and healthy matched control subjects.

Statistical Analysis

  • Men and women were analyzed separately due to the effects of sex on body composition
  • Comparisons of body composition results in the HIV-infected patients and the control subjects were done using paired T-tests on matched patients and control subjects
  • Among HIV-infected patients, those reporting truncal enlargement were compared by T-test for independent samples with those not reporting truncal enlargement
  • The possible relation between truncal enlargement and other variables that could affect body composition was explored by comparing the frequency of occurrence in those with and without abdominal adiposity by Fisher's exact test
  • Separate analyses were done in which HIV-infected patients who reported truncal enlargement were compared with control subjects and with HIV-infected patients without truncal enlargement
Data Collection Summary:

Timing of Measurements

Measurements completed and compared in HIV-infected patients and healthy matched control subjects.

Dependent Variables

  • Body weight, height
  • Whole-body and regional skeletal muscle and adipose tissue contents were measured by magnetic resonance imaging and dual-energy x-ray absorptiometry
  • Total body potassium measured by using a 4-pi whole-body counter
  • Peripheral blood CD4+ lymphocyte counts and plasma HIV RNA contents were determined using standard laboratory methods.

Independent Variables

  • HIV infection
  • Truncal enlargement
  • Antiretroviral medication
  • Specific protease inhibitor use
  • Megestrol acetate
  • Prednisone therapy
  • Use of known anabolic agents, including growth hormone, testosterone and synthetic androgens
  • Participation in an exercise program.

 

Description of Actual Data Sample:

Initial N

26 HIV-infected patients (15 men, 11 women) and 26 healthy matched control subjects (15 men, 11 women). 12 of the HIV-infected patients had evidence of truncal enlargement (7 men, 5 women).

Attrition (final N)

As above.

Age and Ethnicity

HIV-infected men (n=15): 42.4 years±6.7 years, 11 white, three Hispanic, one black

Control men (n=15): 43.0 years±7.9 years, 11 white, three Hispanic, one black

HIV-infected women (n=11): 41.6 years±5.1 years, two white, three Hispanic, six black

Control women (n=11): 41.2 years±5.0 years, two white, three Hispanic, six black.

Anthropometrics

Subjects were matched for sex, race, age and height. There were significant differences between HIV-infected men and control men in regard to weight and BMI.

Location

New York, NY.

 

Summary of Results:

Body Composition Measurements by TBK, DXA and MRI in HIV-infected Patients and Control Subjects

Variables

HIV-Infected Men (n=15) Control Men (n=15) HIV-Infected Women (n=11)

Control Women (n=11)

Body Cell Mass by TBK (kg)

30.4±7.0 32.1±4.7 25.3±7.0 26.9±7.1
Total Fat by DXA (kg) 12.2±5.6, P=0.02 16.7±3.7 17.8±5.5 17.7±9.0
Arm Fat by DXA (kg) 0.8±0.4, P=0.01 1.4±0.4 1.6±0.7 1.9±1.7
Leg Fat by DXA (kg) 2.7±1.8, P=0.001 5.7±1.5 6.7±2.1 7.2±3.2
Trunk Fat by DXA (kg) 8.0±4.2 8.8±2.3 8.7±3.4 8.3±4.9
Trunk Fat:Total Fat Ratio 0.64±0.12, P=0.0008 0.52±0.05 0.48±0.005 0.45±0.003
Total Lean by DXA (kg) 58.6±8.7 59.4±8.1 36.9±4.4 39.4±4.3
Arm Lean by DXA (kg) 6.7±1.4 7.3±1.4 3.8±0.4, P=0.01 4.4±0.7
Leg Lean by DXA (kg) 17.8±5.5, P=0.04 20.9±3.2 11.8±1.6, P=0.007 13.5±1.7
Trunk Lean by DXA (kg) 29.1±4.0 27.6±3.6 18.6±2.7 18.5±2.0

Skeletal Muscle by MRI (L)

28.6±5.8

30.0±4.5

17.4±2.2, P=0.03

20.1±3.3

Other Findings

HIV-infected men and women who noted truncal enlargement had similar amounts of skeletal muscle and subcutaneous adipose tissue but more visceral adipose tissue than HIV-infected patients without truncal enlargement; these values were larger in men (P<0.001) than in women (P=0.08).

The ratio of visceral to subcutaneous adipose tissue was greater in both men (P<0.02) and women (P=0.05) with truncal enlargement.

Two subjects with MRI-confirmed visceral adiposity syndrome were not taking protease inhibitors.

CD4+ lymphocyte counts were higher (P<0.001) and plasma viral burdens tended to be lower (P=0.08) in HIV-infected patients with visceral adiposity syndrome. 

Author Conclusion:

The major finding of this study was excess visceral adipose tissue, with relatively little subcutaneous adipose tissue, in HIV-infected patients with truncal enlargement. Visceral adiposity syndrome occurs in both men and women, is associated with higher CD4+ lymphocyte counts and lower plasma HIV viral burdens, and is not limited to those receiving protease inhibitor therapy.

Funding Source:
Government: NIH Grants AI 21414, DK 42618, DK 37352
Reviewer Comments:

Inclusion/exclusion criteria not described. Cases and controls were recruited from different investigations of the same study. Control subjects not tested for HIV infection. Small numbers of subjects reporting truncal enlargement.

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? No
  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? Yes
  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? Yes
  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? 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? 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.) 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? Yes
  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? Yes
  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? N/A
  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)? Yes
  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