EAL

H/A: Body Composition Measurement (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To compare estimates of percentage body fat mass by bioelectric impedance analysis (BIA) and skinfold measurements, with estimates obtained from dual energy X-ray absorptiometry (DEXA) in HIV-infected male subjects receiving highly active antiretroviral therapy
To determine whether abdominal obesity would alter the relationship between these techniques.

Inclusion Criteria:

Male
Older than 18 years of age
Receiving stable antiretroviral therapy for at least six months
Free of acute AIDS-related events.

Exclusion Criteria:

Excluded if did not meet inclusion criteria.

Description of Study Protocol:

Recruitment

The subjects were adult HIV-infected male patients at the Toronto General Hospital Immunodeficiency Clinic in Toronto. Subjects provided written informed consent.

Design

Cross-sectional study.

Statistical Analysis

For demographic and body-composition variables, differences between patients with waist-hip ratio less than 0.90 and more than 0.90 were tested for significance using the chi-square test for categorical variables and the Student T-test for continuous variables
Paired T-tests were used to assess difference between any two methods
Agreement between the methods, for measurements of percentage body fat mass, was assessed by calculation of the Pearson correlation coefficient and by the method of Bland and Altman using DEXA as a reference method
The difference between the measurements obtained with DEXA and BIA or DEXA and skinfold measurements for each subject was plotted against the mean of the methods.

Data Collection Summary:

Timing of Measurements

Measurements were made and compared. Because different patterns of abdominal fat accumulation might affect the body fat estimation, correlation and agreement of these methods were also compared in patients with waist-hip ratios less than 0.90 and more than 0.90.

Dependent Variables

Percentage body fat mass measured by BIA, skinfold measurements (biceps, triceps and subscapular) and DEXA
Waist and hip circumference and waist-hip ratio
Weight, height, BMI.

Independent Variables

HIV infection
Highly active antiretroviral therapy.

Control Variables

Age
Time since HIV diagnosis
Duration of antiretroviral treatment
HIV viral load
CD4+ T-lymphocyte count
Presence of lipodystrophy.

Description of Actual Data Sample:

Initial N

47 HIV-infected men

Attrition (final N)

Age

49.21 years±1.20 years

Ethnicity

Not mentioned

Other relevant demographics

Of the 47 subjects, six had a waist-hip ratio less than 0.90, and 41 had a waist-hip ratio more than 0.90
CD4+ cell count: 453 cells/mm³±40 cells/mm³
63.8% of patients had an HIV viral load less than 50 copies per milliliter.

Anthropometrics

Patients with waist-hip ratio more than 0.90 were older and had significantly higher CD4 count and BMI
Duration of HIV infection, length of antiretroviral treatment, prevalence of undetectable viral load and lipodystrophy were similar between the two groups.

Location

Canada.

Summary of Results:

Patients	DEXA	Skinfold Measurements	BIA	P-value, Skinfold Measurements	P-value, BIA
All (n = 47)	19.45±0.89	21.25±0.90	18.25±0.59	0.006	0.05
WHR<0.90 (n=6)	14.63±1.67	18.55±2.25	14.27±1.58	0.139	0.904
WHR>0.90 (n=41)	20.15±0.95	21.64±0.97	18.83±0.60	0.004	0.002

Other Findings

Estimates by skinfold measurements were significantly higher and by BIA were significantly lower compared with DEXA for all subjects. This relationship persisted only in those with waist-hip ratios more than 0.90.
Both BIA and skinfold measurements correlated significantly with DEXA, but they did not agree
However, both techniques showed a small intermethod bias, and the precision was within the acceptable range
This relationship persisted in those with waist-hip ratio more than 0.90
In comparison with measurement by BIA, skinfold measurements showed poorer agreement (larger bias and error).

Author Conclusion:

Although a combination of abdominal computed tomography or magnetic resonance imaging with DEXA has been used for quantification of body fat mass, this is not a practical scenario for routine clinical care because of costs and availability of resources. For population studies and perhaps to monitor changes over time for intervention studies, the bias for both BIA and skinfold measurement methods are relatively small, and errors and precision are within the acceptable range when compared with DEXA. Thus, all of these techniques can be used for routine monitoring of total body fat mass in male subjects with HIV infection. The use of these techniques in women must be validated.

Funding Source:

Not-for-profit

Foundation associated with industry:

Reviewer Comments:

The authors note that the use of these techniques in female subjects with HIV infection and body fat redistribution must be validated.

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?	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?	N/A
	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?	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)?	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