EAL

H/A: Body Composition Measurement (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine, using dual-energy X-ray absorptiometry (DEXA) as a basis for comparison, whether the two field methods [i.e., bioelectrical impedance analysis (BIA) and skinfold anthropometry] are able to assess body composition accurately in people with HIV/AIDS.

Inclusion Criteria:

HIV-positive diagnosis was the only entrance criteria
Variety of patients at different stages of HIV disease progression and with different nutrition issues were recruited.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

A convenience sample of patients receiving nutrition intervention was recruited for the study between May 1997 and July 1998.

Design

Cross-sectional study.

Statistical Analysis

Pearson product-moment correlation coefficients were assessed to determine the relationship between DEXA and the two field techniques
Paired T-tests were used to assess differences between the methods
The technique of Bland and Altman was used to determine the bias and the error.

Data Collection Summary:

Timing of Measurements

All assessments were done within a two-week period.

Dependent Variables

Weight, height and body composition were assessed using three different methods
Anthropometric measurements (nine skinfolds, six girths and two bone breadths) were done to the standards of the International Society for the Advancement of Kinanthropometry
BIA was used to estimate fat-free mass or total body water using six different prediction equations
Fat mass, lean tissue and bone mineral content were calculated separately using the DEXA scanner.

Independent Variable

HIV infection.

Description of Actual Data Sample:

Initial N: 36 men

Attrition (final N): 36 men

Age: Mean age, 42.6 years (range, 25 years to 55 years)

Ethnicity: Not described

Other relevant demographics: Mean BMI, 23.3 (range, 15.7 to 31.8). 32 were receiving highly active antiretroviral therapy, whereas four were not taking any antiretroviral therapy. No information on CD4 counts provided.

Location: Australia.

Summary of Results:

Method	Mean±SD	Correlation with DEXA	Bias	Error	Difference
Fat-free mass (kg), DEXA	57.61±9.95	--	--	--	--
Fat-free mass (kg), BIA (Heitmann)	56.89±8.01	0.911, P<0.001	-0.71	4.23	P=0.318
Fat-free mass (kg), BIA (Kotler et al)	58.68±9.21	0.919, P<0.001	+1.08	3.92	P=0.109
Fat-free mass (kg), Skinfold anthropometry (Durnin et al)	60.31±10.31	0.929, P<0.001	+2.70	3.83	P<0.001
Fat mass (% body weight), DEXA	18.23±7.76	--	--	--	--
Fat mass (% body weight), BIA (Heitmann)	20.00±6.38	0.702, P<0.001	+1.77	5.61	P=0.066
Fat mass (% body weight), BIA (Kotler et al)	17.81±4.66	0.772, P<0.001	-0.41	5.11	P=0.632
Fat mass (% body weight), Skinfold anthropometry (Durnin et al)	15.80±5.64	0.828	-2.42	4.43	P=0.002

Other Findings

All field methods showed a highly significant correlation with the DEXA estimates for fat-free mass and fat mass. However, it is the bias or agreement and the error that allow comparison of different techniques.

Two BIA equations (Kotler and Heitmann) did not show a significant difference from the DEXA value.

All of the skinfold prediction equations gave a result for both fat-free mass and fat mass that was significantly different from the DEXA result.

All prediction equations had a similar error, but the BIA prediction equation of Segal et al had the lowest error. The need to know the fat percentage before use limits the application of this equation.

Author Conclusion:

The results of this study suggest that bioelectrical impedance analysis can accurately measure fat-free mass (and fat mass by deduction) in people with HIV/AIDS in our clinic setting, with the use of an appropriate prediction equation (such as that of Kotler or Heitmann). The equation of Kotler et al was developed in both HIV-negative and HIV-positive subjects. The Heitmann equation was developed in a large Danish population, using a four-compartment model of body composition with total body potassium and total body water as the reference methods. Skinfold analysis of persons in our study population tended to overestimate fat-free mass and underestimate fat mass. The Durnin and Womersley equation had the lowest bias of the skinfold equations in our patient group; however, the fat-free and fat mass estimates were still significantly different from the DEXA figures.

Funding Source:

University/Hospital:

Royal Prince Alfred Hospital, Camperdown, Australia

Reviewer Comments:

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)	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?	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?	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?	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?	Yes
	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?	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?	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