EAL

H/A: Body Composition Measurement (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To characterize differences in body composition observed in HIV-infected men at several stages of HIV disease as evidenced by CD4+ T cell count.

Inclusion Criteria:

Male participants of HIV clinical studies sponsored by the National Institute of Allergy and Infectious Diseases (NIAID) and conducted in the HIV Clinic of the Warren G. Magnuson Clinical Center of the National Institutes of Health were invited to participate
Subjects who had been participating in a treatment trial for less than four months were eligible for inclusion
Subjects were recruited into strata representing three disease severity groups according to CD4+ T cell count range.

Exclusion Criteria:

Men who were HIV seronegative
Males who were HIV-infected and who had been participating in a treatment trial for more than four months
Pre-existing co-morbid conditions that might alter nutritional status, such as thyroid disorders, diabetes mellitus and Crohn's disease
The use of total parenteral nutrition.

Description of Study Protocol:

Recruitment

Male participants of HIV clinical studies sponsored by the National Institute of Allergy and Infectious Diseases (NIAID) and conducted in the HIV Clinic of the Warren G. Magnuson Clinical Center of the National Institutes of Health were invited to participate
Subjects who had been participating in a treatment trial for less than four months were eligible for inclusion
Subjects were recruited into strata representing three disease severity groups according to CD4+ T cell count range
Willing subjects were then followed longitudinally for up to three years.

Design

Cross-sectional analysis of a retrospective cohort.

Statistical Analysis

Logistic regression models were used to assess the relationship between each body composition measure, and the odds of being in the less than 200 cells per mm³group was estimated by comparing patients at the 20th percentile of a body composition measure to patents at the 80th percentile
A relative odd that exceeds one implies that patients with the lower body composition value (at the 20th percentile) are more likely to be in Group 1 than those at the 80th percentile
Body composition measures were compared across the three categories of HIV severity using analysis of variance models.

Data Collection Summary:

Timing of Measurements

Participants were followed longitudinally for three years
Group 1 had CD4 counts of less than 200
Group 2 had CD4 counts of 200 to 600
Group 3 had CD4 counts of more than 600.

Dependent Variables

Serum measures of visceral protein stores
Energy intake
Weight: Measured to the nearest 0.1kg, with clothes but without shoes, by use of a calibrated electronic scale
Mid-arm Circumference
- MAC was measured to the nearest 0.1cm using a flexible, metric, non-stretch tape
- Midpoint between the acromium and the olecranon process was marked while the subject's right arm was bent at a 90-degree angle
- MAC measurement was taken with the arm hanging loosely at the subject's side
Mid-arm muscle area (MAMA)
- Was calculated from previous anthropometric measures using the formula MAMA equals MAC minus [(triceps skinfold average x pi)² divided by (4pi)]
- 10cm² was subtracted for male subjects
BIA
- Tetra-polar bioelectrical impedance was measured using RJL System 101 plethysmography with four self-adhering electrodes placed on the distal surfaces of hands and feet according to the RJL Systems recommendations.

Independent Variables

CD4+ T cell status.

Control Variables

Age.

Description of Actual Data Sample:

Initial N: 107 HIV-infected men were recruited to participate
Attrition (final N): 106 men; one was excluded because he was started on TPN during the study.

Age

CD4 count less than 200 mean age was 36±6 years
CD4 count 200 to 600 mean age was 3±7 years
CD4 count more than 600 mean age was 34±8 years.

Ethnicity

White: 82.1%
Black: 12.3%
Hispanic: 4.7%
Other: 0.9%.

Other relevant demographics:

All subjects were ambulatory and seen in the outpatient clinic
Mean heights were similar across groups.

Anthropometrics

All measures of body composition estimating body fat, including BMI, triceps and subscapular skinfolds and percentage of body fat wee significantly lower in patients in Group 1
Using MAMA, a measure of FFM, muscle was also significantly lower in Group 1 than the other groups
Groups 2 and 3 were not significantly different from each other on the same body composition measures.

Location

Bethesda, MD.

Summary of Results:

Findings

Mean BMI was significantly less for each group of men in Groups 1, 2, and 3 as compared with mean BMI (25.8±4.0) for men in the same age range from the NHANES I and II data (P<0.01)
Muscle mass, as estimated by MAMA, was significantly less in the entire HIV group within each range of CD4 count as compared with men of the same age (55.1 m²±11.6, P<0.001)
Patients at the 20th percentile of BMI have a sixfold excess (P<0.001) of being in the low CD4 group as compared with those whose BMI is at the 80th percentile
There is a seven- to eightfold excess in the odds of being in the low CD4 group at the 20th percentile of TSF as compared to those at the 80th percentile (P<0.001)
TSF remains significantly related to the odds of being in the low CD4 group (P<0.05) in the presence of other body composition measures
This suggests that TSF contains unique information that is able to characterize body composition of HIV-infected individuals
Serum levels of albumin, prealbumin and transferrin were within normal limits for all three groups, with no statistically significant differences observed between the groups
By total daily kilocalorie intake or by kilocalories per kilogram, there were no significant differences between the three CD4 groups.

Author Conclusion:

People with advanced HIV disease also have decreased fat stores compared to those with HIV infection who are at earlier stages of disease as reflected by CD4+ cell count
Measures of visceral protein stores were normal in this cohort
Kilocalorie intake appeared adequate and was not different in those who had lower CD4 counts or lower percentages of fat or muscle
Despite seemingly adequate kilocalorie intake, there was noted reduced weight and BMI, and reduced fat and muscle stores, in those with more advanced disease
Measurement of TSF and MAC may be simple measures that along with weight, help predict changes in body composition in HIV-infected individiuals over time.

Funding Source:

Government:	National Institutes of Health, National Institute of Allergy and Infectious Diseases
University/Hospital:	HIV Clinic of the Warren G. Magnuson Clinical Center of the National Institutes of Health

Reviewer Comments:

Prospective cohorts of HIV-infected indviduals at different states of disease should be followed longitudinally to see if these observations play out
Data about changes in body composition will assist in the development and evaluation of targeted interventions.

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?	???
	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.)	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?	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?	???
	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?	???
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