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H/A: Body Composition Measurement (2009)

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

To compare racial/ethnic differences and effects of HIV on body composition among antiretroviral-naive HIV seropositive men to a representative sample of HIV seronegative men. It was hypothesized that the effect of HIV infection would be uniform across all racial/ethnic groups.

Inclusion Criteria:
  • 1,996 HIV-negative men from NHANES 1999 to 2002, aged 20 to 59 years 
  • 321 antiretroviral therapy-naive HIV-positive men from CPCRA 061, aged 20 to 59 years.
Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

Cross-sectional analyses of HIV-negative men from NHANES 1999 to 2002 and antiretroviral therapy-naive HIV-positive men from CPCRA 061 were compared.

Design

Case-control study. 

Statistical Analysis

  • Means and standard deviations of the study parameters were calculated for each combination of race/ethnicity and HIV status
  • Multiple regression model was fitted for each body composition and anthropometric measurement using race/ethnicity, HIV status, age in 10-year increments, cigarette smoking, hepatitis C status and the interaction of race/ethnicity by HIV
  • The means for each race/ethnicity by HIV group was estimated using the fitted model
  • Comparisons of race/ethnicity by HIV group means were made using Student T-test and were adjusted for age, smoking and hepatitis C
  • To summarize the impact of HIV infection on the anthropometric measurements, the difference between the adjusted means of HIV-seronegative and HIV-seropositive groups were determined and expressed as a percent of the mean of the HIV-seronegative group.
Data Collection Summary:

Timing of Measurements

Measurements were made and compared.

Dependent Variables

  • Height, weight and BMI
  • Regional subcutaneous fat area was estimated by skinfold caliper (triceps, subscapular)
  • Mid-arm, waist and thigh circumferences 
  • Total body fat, fat-free mass and body fat index were derived by Durnin-Womersley formula
  • Bioelectric impedance analysis was used to assess total body fat, fat-free mass and body cell mass. Since different techniques were used in each study, all NHANES BIA results were calibrated or recalculated to allow comparison of measurements obtained by the two kinds of BIA machines.

Independent Variables

HIV-negative and antiretroviral therapy-naive HIV-positive men.

Control Variables

  • Age
  • Smoking
  • Hepatitis C.
Description of Actual Data Sample:
  • Initial N: 321 HIV-positive men and 1,996 HIV-negative men
  • Attrition (final N): As above.

Age and Ethnicity

  • Latino HIV-negative (N=695): Mean age 34.0±8.8 years, 829±489 CD4+ cells per mm3
  • Latino HIV-positive (N=35): Mean age 36.0±7.0 years, 193±159 CD4+ cells per mm3
  • African American HIV-negative (N=404): Mean age 35.5±8.9 years, 798±158 CD4+ cells per mm3
  • African American HIV-positive (N=175): Mean age 39.1±10.7 years, 198±177 CD4+ cells per mm3
  • Caucasian HIV-negative (N=897): Mean age 35.1±8.5 years, 1,002±236 CD4+ cells per mm3
  • Caucasian HIV-positive (N=111): Mean age 38.2±8.6 years, 242±201 CD4+ cells per mm3.

Anthropometrics

Cases and controls were age- and sex-matched. HIV disease variables were comparable across the three racial/ethnic groups.

Location

United States.

 

Summary of Results:

Other Findings

HIV-positive men were older and more likely to be smokers than HIV-negative men. 

The HIV-negative men were heavier in weight (+17.8kg, P<0.001) and had higher BMI (+4.3kg/m2, P<0.001), body cell mass (+2.4kg, P=0.02), fat-free mass (+5.9kg, P<0.001) total body fat (by Durnin Womersley, +5.95kg, P<0.001), body fat index (+1.6kg/m2, P<0.001) and regional fat mass than the HIV-positive men.

In the multivariate model, there were significant percentage differences between HIV-negative and HIV-positive African American men for all body composition measurements (weight, +15.3%; BMI, +14.5%; body cell mass, +5.2%; total body fat by Durnin Womersley, +15%; body fat index, 13.9%; fat-free mass by Durnin Womersley, 7.9%) and all circumference and skinfold measurements (all P<0.05).

For Caucasian men, the following differences were significant between HIV-negative and HIV-positive: Weight, +14.4%; BMI, +14.0%; body cell mass, +6.0%; total body fat by Durnin Womersley, +17.7%; body fat index, 17.1%; fat-free mass by Durnin Womersley, 8.7%; and all circumference and skinfold measurements.

Similarly, among Latino men the following differences were significant: Weight, +10.1%; BMI, +12.3%; fat free mass by Durnin Womersley, +7.7%; and arm, waist, and thigh circumferences and mid-arm skinfold fat area.

Latinos when compared to African Americans had greater body fat index (+0.94kg/m2, P=0.02), waist circumference (+5.4cm, P=0.04), triceps skinfold (+3.6cm, P<0.001) and mid-arm skinfold fat area (+4.6cm2, P=0.04) but had significantly lower fat-free mass (-3.5kg, P=0.04).

Comparing Latinos to Caucasians, the body fat index (+0.74kg/m2, P=0.09) and triceps skinfold (+2.7cm, P=0.03) were greater among Latinos, but fat-free mass (-3.97, P=0.002) was significantly lower.

When African Americans were compared to Caucasians, the only variable significantly different was waist circumference, with African Americans having 3.8cm less than Caucasians (P=0.03).

The interaction terms for race/ethnicity were not significant across the three racial groups for weight, BMI, body cell mass, total body fat by BIA, and body fat index.   

Author Conclusion:

In conclusion, when compared to HIV-seronegative individuals, the known racial/ethnic effects on body composition, such as increased fat mass among Latinos, higher fat free mass among African Americans and differences in fat patterning between Caucasians and African Americans, are outweighed by the effect of HIV infection itself in this antiretroviral-therapy naive group of men. These data have important implications in our understanding of the evolution in racial/ethnic differences in body composition changes with the antiretroviral therapy-associated HIV lipodystrophy syndrome. A reliable assessment of effects of HIV across different racial/ethnic groups among antiretroviral therapy-naive subjects will be increasingly important in delineating the pathogenesis and management of this syndrome as antiretroviral therapy becomes widely available in many diverse populations worldwide.

Funding Source:
Government: NIH, NIAID 5U01AI042170-10, 5U01AI046362-03
Reviewer Comments:

Measurements made from different BIA machines were recalculated for comparability, but there may still be a margin of error, as noted by the authors. Authors note the additional following limitations:

  • Difficult to extrapolate the results to women
  • Unable to account for all factors that might contribute to racial variations in body composition, including environmental, socioeconomic, genetic and ethnic differences
  • Reproducibility of Durnin Womersley in other racial/ethnic groups is limited
  • Inability to match for all confounding variables, such as HCV and smoking. 
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) 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? ???
  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? ???
  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? ???
  7.7. Were the measurements conducted consistently across groups? ???
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