EAL

H/A: Body Composition Measurement (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To compare fat-free mass in children with HIV infection with that of control children
To assess the contribution of fat-free mass to body weight in HIV-infected children compared with that of control children
To study the relationships between body weight, fat-free mass and mortality.

Inclusion Criteria:

HIV-infected subjects: Vertically transmitted HIV infection as defined by CDC criteria
Control subjects: Normally nourished at clinical assessment and free from acute or chronic medical conditions that could potentially affect their nutritional status.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

Prepubertal children with vertically transmitted HIV infection were recruited between January 1995 and December 1996 from the First and Fourth Pediatric Departments of the University of Milan. They were compared with children attending the department clinics for well visits or for scheduled minor surgery.

Design

Case-control study. Measurements were made in HIV-infected children and control subjects (without HIV)

Statistical Analysis

Categorical variables were compared using the chi-square test
Continuous variables were compared with one-way ANOVA after confirming their normal distribution by standardized coefficients of skewness and kurtosis within the range of -2 to 2
When the ANOVA F ratio was statistically significant, a post-hoc multiple range analysis was done by using Tukey's test to compare HIV-infected children in different clinical categories and control children
Scheffe's method was used to test the difference between control children and the entire group of HIV-infected children
With the above sample size and a type 1 error fixed at 0.05, the study had a probability of more than 0.80 of detecting a 10% difference between HIV-infected and control children for weight and fat-free mass (type 2 error=0.20)
Survival probabilities were estimated with the Kaplan-Meier product-limit procedure
Survival rates were compared with the log-rank test.

Data Collection Summary:

Timing of Measurements

Measurements made in cases and controls and compared. All measurements were made in the morning after children fasted overnight.

Dependent Variables

Weight, height and body mass index
Non-dominant upper-arm circumference
Upper arm area and upper arm muscle area
Fat-free mass was estimated from single-frequency bioelectrical impedance analysis by using three different published equations
Fat-free mass was estimated from triceps skinfold thickness measurements.

Independent Variable

HIV infection.

Description of Actual Data Sample:

Initial N: 86 HIV-infected children (36 boys, 50 girls), 113 control children (without HIV) (50 boys, 63 girls)

Attrition (final N): As above

Age: Mean age, 6.9 years (range 0.8 years to 13.1 years) for HIV-infected children, 7.7 years (range 0.8 years to 14.2 years) for control children

Ethnicity: Not mentioned

Location: Italy.

Summary of Results:

Variables	Controls (n=113)	Asymptomatic (n=11)	Mildly Symptomatic (n=23)	Moderately Symptomatic (n=22)	Severely Symptomatic (n=30)	All (n=86)
Weight (kg)	27.8±12.3	27.8±14.3	24.1±7.0	19.8±9.1	20.2±6.6	22.1±9.0
Weight-for-age z-score	0.09±1.00	0.44±0.90	-0.31±0.75	-0.81±1.13	-0.91±1.17	-0.55±1.11
Height (cm)	124.5±21.5	120.0±26.7	121.3±16.7	110.2±19.9	112.8±18.3	115.3±19.7
Height-for-age z-score	0.00±0.91	-0.06±0.84	-0.29±0.91	-0.82±1.28	-1.19±1.01	-0.71±1.11
FFM (kg), Goran et al	20.5±8.4	19.6±9.9	18.2±5.5	14.4±6.7	14.9±5.2	16.3±6.6
FFM (kg), Houtkooper et al	21.9±8.3	21.3±10.1	19.5±5.4	15.9±6.7	16.3±5.0	17.8±6.6
FFM (kg), Arpadi et al	22.0±8.2	20.9±10.0	20.2±5.7	16.4±6.9	17.2±5.5	18.3±6.8
Upper arm area (cm²)	3,079±1112	3,214±1,145	2,582±550	2,475±985	2,341±626	2,554±827
Upper arm muscle area (cm²)	2,157±663	2,162±691	1,890±398	1,730±624	1,678±402	1,811±525

Other Findings

All four estimates of body composition showed that fat-free mass in HIV-infected children was significantly less than in control children of similar age.

However, fat-free mass as a percentage of body weight was not significantly different between groups.

In the whole group of HIV-infected children, an age-specific z-score less than -2 for weight and for fat-free mass was significantly associated with an increased risk of death [relative risk (95% confidence interval)=11.4 (3.1, 41.0) and 5.1 (1.5, 18.2), respectively]; when only children with more severe disease were considered, only z-score for weight was significantly associated with an increased risk [4.6 (1.4, 14.9)].

Author Conclusion:

These findings suggest that no preferential catabolism of fat-free mass occurs in HIV-infected children and that body weight-for-age is a better prognostic indicator than is fat-free mass estimated by bioelectrical impedance analysis. Further studies, mainly longitudinal cohort studies, are needed to precisely describe the time course of body composition changes in HIV-infected children. Nevertheless, the whole-body data from our study show that there is no apparent preferential reduction in fat-free mass in HIV-infected children by the age of seven years. This suggests that poor energy intake could be the main cause of their weight loss or growth faltering. If confirmed, these results could advocate for vigorous nutritional support, either enteral or parenteral, early in the course of the disease.

Funding Source:

Government:

Grant 9409-19 from Ninth Research Project on AIDS of Italian Health Ministry

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)	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?	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.)	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?	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?	Yes
	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?	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?	N/A
	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