EAL

H/A: Body Composition Measurement (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To assess the agreement between eight methods of estimating lean-body mass in HIV-infected men.

Inclusion Criteria:

None specifically mentioned.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

From June 1991 to February 1992, all consenting HIV-infected men seen at the Houston Veterans Affairs Special Medicine Clinic were enrolled.

Design

Cross-sectional study.

Statistical Analysis

Means, standard deviations of the means and medians were calculated on all anthropometric measurements
The paired T-test was used to compare each alternate estimate of lean-body mass with the TOBEC estimate
Agreement was assessed by comparing the difference between two methods (the bias) with the mean of those two methods
This statistical approach evaluates whether two methods are similar enough that measurements from one might accurately replace those of the other.

Data Collection Summary:

Timing of Measurements

Measurements were made in subjects and compared.

Dependent Variables

Height, weight, BMI
Skinfold measurements of the triceps, abdomen, chest, mid-axilla, thigh, subscapular and supra-iliac
Lean body mass was determined by the prediction equations of Brozek and Keys, Sloan, Wilmore and Behnke, Jackson and Pollock, Lohman and Eddy
Lean body mass was measured by bioelectrical impedance assessment, by prediction equations that used anthropometric measurements and by total body electrical conductivity as the comparison method.

Independent Variables

HIV infection.

Description of Actual Data Sample:

Initial N: 255 enrolled subjects
Attrition (final N): 27 outpatient HIV-infected men agreed to have TOBEC measurements. BIA was not possible for one subject due to skin lesions. Assessment and anthropometric measurements were missing for four subjects. Thigh skinfolds were not possible on two other subjects who had tight skinfolds.
Age: Mean age, 43.6±8.6 years
Other relevant demographics: Mean BMI, 22.8±3.3
Location: Houston Veterans Affairs Special Medicine Clinic.

Summary of Results:

Fat-free Mass Estimates	Mean FFM±SE (kg)	R, P-value	Mean BIAS±SD (kg)	SEE (kg)
TOBEC (N=27)	55.98±1.96	---	---	---
Brozek and Keys (N=25)	63.71±1.89	R=0.92, P=0.69	7.07±4.04	5.73
Jackson and Pollock (N=23)	60.03±1.74	R=0.93, P=0.88	3.00±4.30	3.62
Wilmore and Behnke (N=25)	58.98±1.65	R=0.90, P=0.87	2.34±4.70	3.65
Lohman (N=25)	58.84±1.61	R=0.88, P=0.86	2.20±5.01	3.81
Eddy (N=27)	56.34±1.32	R=0.87, P=0.86	0.36±5.39	3.74
BIA (N=24)	55.18±1.27	R=0.89, P=0.85	-1.36±5.75	4.09
Sloan (N=23)	60.78±1.60	R=0.80, P=0.76	3.74±6.46	5.19

Other Findings

The mean ±SE for lean body mass were 55.98±1.96kg for total body electrical conductivity and 55.18±1.27kg for bioelectrical impedance assessment; they ranged from 55.18±1.27 to 63.71±1.89 for the prediction equations.

Author Conclusion:

In conclusion, we compared lean-body mass estimates from TOBEC with several inexpensive alternate methods in HIV-infected men. Unfortunately, none of these alternative methods gave values that could satisfactorily replace the TOBEC estimates. However, our results indicate that of the more simple methods, the Eddy formula, which is calculated on the basis of height and weight, could be appropriate for evaluating group means. In previous research, we documented that anthropometric measurements are reproducible when made by trained individuals. These results, together with those reported here, indicate that the Brozek and Keys formula, which uses abdominal, chest and triceps skinfold measurements, may be more useful than bioelectrical impedance analysis in following lean-body mass changes in an individual.

Funding Source:

Government:	Houston VA Research Center for AIDS and HIV Infection (RCAHI), Dept of VA Health Services Research and Development (HSR & D) Houston Field Program
University/Hospital:	Baylor College of Medicine Biomedical Research Support Grant (USPHS Grant RR-05425)

Reviewer Comments:

Inclusion/exclusion criteria not well defined. Only 27 of 255 enrolled subjects had TOBEC measurements. Data was missing for several subjects. Authors note that a potential limitation of the research is the extent to which the estimates may have been affected by abnormalities of fluid balance.

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?	???
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
3.	Were study groups comparable?		N/A
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	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.)	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?		???
	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?	???
	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?	Yes
	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?		???
	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?	???
	7.7.	Were the measurements conducted consistently across groups?	N/A
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)?	???
	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