H/A: Body Composition Measurement (2009)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
  • To compare longitudinal changes in anthropometric measurements among HIV-infected men and HIV-seronegative control subjects
  • To better define body composition changes that occur over time in HIV-infected patients by using measures readily available to clinicians.
Inclusion Criteria:
  • Participants enrolled in the Multicenter AIDS Cohort Study (MACS) who participated in the 31st visit
  • Underwent circumference measurements of the waist, thigh, hip and mid-arm
  • Provided information regarding use of antiretroviral therapy (ART)
  • Participated in four years of follow-up study from the 31st semi-annual visit to the 39th semi-annual visit, which occurred between April 2003 and September of 2003. 
Exclusion Criteria:
  • MACS participants who did not participate in the 31st semi-annual visit
  • Participants who did not report information about ART use in the last six months
  • HIV-infected patients not enrolled in the MACS.

 

Description of Study Protocol:

Recruitment

  • The MACS is an ongoing prospective study of the natural and treated history of HIV infection among homosexual and bisexual men in the United States
  • MACS participants attend follow-up study visits semi-annually.

Design

Prospective cohort study.

Statistical Analysis

  • Multivariate linear mixed effects regression models were implemented using the SAS PROC MIXED procedure (SAS Institute, Cary, NC)
  • For between-group comparisons of each outcome measure, Bonferroni correction for multiple pairwise comparisons among the four groups was implemented to control the family-wise error rate
  • A P-value less than 0.01 (0.05/6) was considered statistically significant for these comparisons.
Data Collection Summary:

Timing of Measurements

  • Semi-annually
  • From April 1999 to April-September 2003.

Dependent Variables

  • Body mass index (BMI)
    • A wall-mounted stadiometer was used to measure height
    • The participant was weighed while wearing minimal clothing or an examination gown.
  • Waist (cm)
  • Hip (cm)
  • Waist:hip ratio 
  • Arm (cm)
  • Thigh (cm)
    • All circumferences were measured with the participant in a standing position using the protocol established in the Third National Health and Nutrition Examination Survey
    • Examiners at all sites underwent the same videotape instruction.

Independent Variables

  • ART exposure
  • Single continuous covariate representing time in years since the index visit.

Control Variables

  • Age
  • Nadir CD4 count
  • BMI.

 

Description of Actual Data Sample:

Initial N

5,622 men originally enrolled between 1983 to 1984 and 1987 to 1991. 1,857 men were censored in 1996 and 1,750 men had died by April 1999, leaving 2,015 individuals. 1,064 of these men (53%) participated in the 31st semi-annual visit.

Attrition (final N)

1,053 men; 11 men were excluded for not reporting information about ART.

Age

40 years to 53 years.

Ethnicity

Not disclosed.

Other relevant demographics

The study population was divided into 4 groups

  • HIV seronegative (n=392)
  • HIV-infected but not receiving ART (n=94)
  • HIV-infected receiving mono/combo-ART (n=79)
  • HIV-infected receiving highly active antiretroviral therapy (HAART) (n=488).

Anthropometrics

  • The HIV-seronegative group was older and had a higher BMI than each of the HIV-infected groups
  • The proportion of subjects who were white was similar in the HIV-seronegative and HIV-infected mono/combo-ART group and HAART-treated group but was lower in the HIV-infected untreated group (P=0.02 vs. HIV-infected HAART-treated group)
  • Among HIV-infected groups, the baseline CD4 cell count was similar
  • HIV viral load was highest among untreated HIV-infected men
  • Nadir CD4 count cell count was also highest in the HIV-infected no-ART group, significantly higher than in the HIV-infected HAART-treated group
  • The proportion of men with an undetectable viral load was higher in the HIV-infected HAART-treated group than in the HIV no-ART group (P<0.01) and the HIV mono/combo-ART group (P<0.01).

Location

  • Baltimore
  • Chicago
  • Pittsburgh
  • Los Angeles.
Summary of Results:

Findings

  • BMI increased significantly in the HIV-seronegative group (0.12 per year±0.04 per year; P=0.001 vs. no change)
  • BMI remained constant in each of the HIV-infected groups
  • All groups showed significant yet similar increases in waist circumference
  • Each group showed significant increases in hip circumference over the study interval
  • Men not treated with HAART tended to have higher rates of change in hip circumference compared with those who received HAART (HIV-infected no-ART group, 0.51cm per year± 0.14cm per year, and HIV-infected mono/combo-ART group, 0.63cm per year±0.18cm per year; both P=0.03 vs. HIV-infected HAART-treated group)
  • Waist:hip ratio increased over time among the HAART recipients and the HIV-infected no-ART group (P=0.027 and P=0.001, respectively) but not in the HIV-infected mono/combo-ART group or among HIV-seronegative men
  • Average thigh circumference increased significantly in the HIV-seronegative groups (P=0.024 vs. no change) but not in the HIV-infected groups
  • Rates of thigh circumference change in the HAART-treated group were lower than in the HIV-seronegative group (-0.14cm±0.21cm per year vs. 0.54cm±0.24cm per year; P=0.03)
  • Arm circumference remained constant in all the groups.

 

Author Conclusion:
  • The average change in thigh circumference was clearly different for HAART recipients compared with HIV-seronegative men. However, consistent with comparative patterns observed in hip circumferences, the changes in arm circumferences were no different among the HIV-infected and seronegative groups.
  • These findings may indicate that peripheral fat wasting is more pronounced in the lower extremities
  • Circumference measurements cannot distinguish between fat, muscle and other tissues, so this hypothesis needs to be pursued with more sophisticated measurement techniques. 
Funding Source:
Government: National Institutes of Health, National Institute of Allergy and Infectious Diseases, National Cancer Institute
University/Hospital: Johns Hopkins University Bloomberg School of Public Health, Northwestern University, UCLA School of Public Health, University of Pittsburgh
Reviewer Comments:
  • This analysis was limited by the small size of the groups and the fact that they might have had prior exposure to other antiretrovirals before the time period included in this analysis
  • Anthropometric measurements were obtained in the MACS beginning in 1999, three years after the introduction of HAART
  • There is no data for HAART recipients immediately subsequent to therapy initiation, so it is not possible to exclude other body habitus changes in the time after HAART initiation.
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? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? No
  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? 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.) N/A
  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? ???
  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? ???
  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? 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? 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)? 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