EAL

H/A: Body Composition Measurement (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

Body wasting is an increasingly prevalent AIDS-defining condition and an independent risk factor for mortality in patients infected with HIV. Largely based on studies conducted early in the epidemic, HIV-associated wasting has been assumed to feature a disproportionate loss of lean tissue. The authors report results from cross-sectional and longitudinal studies that differ from earlier observations.

Inclusion Criteria:

HIV-infected men with documented weight loss of 10% or more
HIV-positive men without marked weight loss
HIV-negative control subjects selected by body mass index.

Exclusion Criteria:

Patients with overt symptoms of opportunistic infections
Any person who used hormonal anabolic therapies such as growth hormone or testosterone during time of measurements.

Description of Study Protocol:

Recruitment

Recruitment methods not specified.

Design

Cross-Sectional Analysis: Weight and body composition in 32 HIV-infected men with documented weight loss of 10% or more (mean -11.4kg±0.6kg) were compared with 46 HIV-positive men without marked weight loss and 32 HIV-negative control subjects

Longitudinal Analysis: Composition of weight lost over time was evaluated in paired measurements done three months to 24 months apart in 20 HIV-infected men with and without prior weight loss.

Statistical Analysis

Analysis of variance and Student's T-test using a two-sided (alpha) of 0.05 for statistical significance.

Data Collection Summary:

Timing of Measurements

Data collected on each person at time intervals between three and 24 months apart.

Dependent Variables

Change in lean body mass (LBM) in kilograms
Change in body cell mass (BCM) in kilograms
Change in fat in kilograms
Weight measured on a calibrated scale with subjects fasting and clothed in hospital gown
LBM and fat measured using dual-energy X-ray absorptiometry (DEXA) (lunar model DPX, Madison, WI)
Resistance and reactance, measured by bioelectrical impedance analysis (BIA) (Valhalla Model 1990B, San Diego, CA), were used to calculate BCM using a published equation validated against reference method, TBK counting.

Independent Variables

HIV-positive with 10% weight loss
HIV-positive with CD4 less than 200
HIV-positive with CD4 more than 200
HIV-negative control subjects.

Control Variable

Sex.

Description of Actual Data Sample:

Initial N

128 males

Cross-sectional analysis:

32 HIV-infected men with documented weight loss
46 HIV-positive men without marked weight loss
32 HIV-negative control subjects

Longitudinal Analysis:

10 HIV-positive with more than 15% body fat
10 HIV-positive with less than 15% body fat.

Attrition (final N)

110 males.

Age

About 38 to 40 years.

Ethnicity

95 white, 15 other races.

Other relevant demographics

CD4 84 + 85 in >10% wt loss and HIV CD4 < 200
Most HIV-infected men reported homosexual contact as primary risk factor
Only two subjects reported previous IV drug use.

Anthropometrics

Subjects were similar in anthropometrics
Height: 176cm to 179 cm
Weight: 65.9 - 70 - 74 - 77.4 kg average.

Location

California.

Summary of Results:

Cross-sectional Comparison

Variables

HIV-positive with 10% Weight Loss

(n=32)

HIV-positive with CD4<200

(n=28)

HIV-positive with CD4>200

(n=18)

HIV-negative Control Subjects

(n=32)

Significance

Change in LBM

30.6±0.4

31.5±0.7

32.0±0.4

32.5 ± 0.6

P=0.01

Change in BCM

16.1±0.2

17.3±0.3

18.2±0.3

18.4±0.3

P<0.0001

Change in fat

4.6±0.3

7.2±1.0

8.0±0.5

9.0±0.6

P<0.0001

Longitudinal Comparison

Variables

HIV-positive with >15% Body Fat

(n=10)

HIV-positive with <15%
Body Fat (n=10)

Significance

Change in weight (kg)

2.3±0.4

2.5±0.5

P=0.75

Change in weight as LBM (%)

16%

70%

P=0.03

Change in LBM (kg)

0.4±0.5

1.8±0.3

P=0.03

Change in fat (kg)

1.9±0.5

0.7±0.4

P=0.10

Other Findings

Fat, LBM and BCM were significantly lower in men with weight loss relative to controls (P<0.001 for fat and BCM, P=0.001 for LBM).

Two thirds of the difference in weight was fat.

Weight loss in patients with baseline fat of more than 15% was only 16% LBM, but the composition of weight lost in men with baseline fat of less than 15% was 70% LBM.

Author Conclusion:

The composition of weight loss in HIV-infected patients in our study is consistent with that seen in healthy obese and lean individuals during reduced energy intake. We conclude that progressive decreases in fat and lean tissue occur in men with HIV infection, with the composition of weight lost depending on baseline fat content. These results argue against the widely held notion that HIV-associated wasting is characterized by preservation of fat at the expense of lean tissue.

Funding Source:

Government:

NIH DK45833, RR-00083 and Bay Area Nutrition Center

Reviewer Comments:

Authors note that the results of the study should be interpreted with caution:

Results have been compared with other studies using different techniques for measuring body composition and different populations
Because complete weight and body composition histories were not available for all individuals in the longitudinal study, the authors cannot speculate about changes in weight or body composition that may have occurred before the study or their potential effects on the composition of weight lost during the period of observation
Information on levels of energy intake and physical activity, which may have influenced the results, were not available
Because DEXA cannot characterize the composition of lean body mass, the technique may have underestimated loss of body cell mass in paired studies.

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)	Yes
	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)	Yes

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?	No
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?	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?	???
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.)	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?		N/A
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	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%.)	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	N/A
	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?	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?	???
	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?	???
	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?	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