EAL

H/A: Body Composition Measurement (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To study the change in body composition of breast-feeding mothers living in a poor rural community in relation to their HIV status.

Inclusion Criteria:

Mothers who were participating in an ongoing Africa Center for Health and Population Studies study (the Vertical Transmission Study, a study investigating the relationship between exclusive breast-feeding and HIV transmission). Mothers were offered entry into this study when they brought their infant to clinic for routine six-week immunizations.
HIV-negative women recruited among women not participating in that study
Mothers were enrolled at six weeks post-partum.

Exclusion Criteria:

Had to meet inclusion criteria.

Description of Study Protocol:

Recruitment

Six-week post-partum mothers at a single clinic in a peri-urban township and two clinics in more rural areas (South Africa).

Design

Longitudinal observational prospective case-control study: Mothers were enrolled at six weeks post-partum, with subsequent study visits at 14 and 24 weeks. Anthropometric measurements, health information and laboratory data were collected at each visit to compare body composition changes in HIV-positive vs. HIV-negative breast-feeding women.

Blinding Used

Field and laboratory staff members were blinded to the participant's HIV status.

Statistical Analysis

Multivariate analysis of variance (MANOVA) on the body composition measurements
Multivariate analysis of covariance (MANCOVA) on the change in anthropometric variables
For demographic and body composition variables, Χ² for categoric variables and the Student T-test for continuous variables
For longitudinal measures, the groups were compared using repeated-measures analysis of co-variance (ANCOVA)
Stepwise regression analysis for the following variables: Fever, upper or lower respiratory illness, C-reactive protein, CD4 count, viral load, change in CD4 count, change in viral load, years of education and number of previous pregnancies.

Data Collection Summary:

Timing of Measurements

Eight, 16, and 24 weeks post-partum.

Dependent Variables

General health information: A nurse obtained a history of illnesses since previous visit (respiratory status, diarrhea, presence of fever)
HIV viral load and CD4 T-cell counts: Determined at the Africa Center Virology lab
Indicators of inflammation: C-reactive protein and α-1-acid glycoprotien (AGP) were tested in the Biochemistry Department at the University of KwaZulu-Natal in Durban, South Africa
Anthropometric measurements: Height, weight, BMI, midarm circumference, skinfold thickness using Lange calipers at four body sites (triceps, biceps, subscapular and midline suprailiac)
Bioimpedance spectrometry: BIS4000 Analyzer.

Independent Variables

Breastfeeding status was self-reported
HIV infection.

Description of Actual Data Sample:

Initial N: 142 enrolled
Attrition (final N): 118 at final measurements
Age: 25 years old
Ethnicity: South African.

Other Relevant Demographics

Median CD4+ count was 621 (range 101 to 1,585) cells per µL
95% had CD4+ counts more than 200 cells per µL.

Location

Northern KwaZulu-Natal province, South Africa; largely rural area with one peri-urban township. Most inhabitants are of Zulu ethnic origin.

Summary of Results:

Variables	Eight weeks HIV-positive (N=88)	Eight weeks HIV-negative (N=46)	24 weeks HIV-positive (N=61)	24 weeks HIV-negative (N=40)	Significance
C-reactive protein, g per L antilog of mean (±SD)	0.006 (0.040)	0.004 (0.018)	0.010*(0.051)	0.005*(0.037)	* P=0.056
AGP, g per L	1.19* (0.44)	1.03* (0.24)	1.09 (0.46)	0.98 (0.25)	*P=0.007

Variables	Eight weeks HIV-positive(N=92)	Eight weeks HIV-negative (N=50)	24-week HIV-positive (N=68)	24-week HIV-negative (N=45)	Δ Week Eight to 24 HIV-positive	Δ Week Eight to 24 HIV-negative	Significance
Weight, kg	62.7 (8.6)	63.9 (13.9)	61.1 (9.0)	65.4 (15.3)	-1.4 (3.1)	0.4 (3.3)*	P=0.004
BMI, kg/m²	24.6 (3.2)	25.3 (5.0)	24.1 (3.3)	25.7 (5.6)	-0.54 (2.0)	0.15 (1.3)*	P=0.005
TSF, mm	18.1 (4.5)	19.0 (5.5)	17.6 (5.2)	21.7 (7.3)*	-0.3 (4.4)	1.8 (4.9)**	P=0.002 *P=0.013

Other Findings

At eight weeks, HIV-positive and HIV-negative women were not significantly different in height, weight, BMI, fat-free mass, or fat mass
Between eight and 24 weeks, HIV-positive mothers had a mean weight loss of 1.4kg in contrast to a 0.4kg weight gain in HIV-negative mothers (P<0.01)
There were no significant group differences with regard to change in fat mass or fat-free mass
No significant difference in body composition (as measured by bioimpedance) by HIV status at eight and 24 weeks post-partum
In HIV-positive mothers the change in weight was not correlated to the change in CD4 count or viral load and was not different when controlling for initial CD4 count or viral load.

Author Conclusion:

HIV-positive South African breastfeeding mothers without severe immune suppression lost weight and subcutaneous fat between eight and 24 weeks post-partum. HIV-negative mothers gained weight during the same time period. Fat-free mass was maintained post-partum in HIV-positive and HIV-negative mothers. Further study needed to determine whether weight and fat loss in normal and overweight breast-feeding HIV-positive mothers is associated with long-term consequences.

Funding Source:

Government:

M Bennish supported by National Institute of Allergy and Infectious Diseases of the US National Institutes of Health. M Van Loam supported by US Dept of Agriculture

Not-for-profit

Foundation associated with industry:

Reviewer Comments:

Did not mention how HIV-negative women were recruited
Breastfeeding status was self-reported and the authors mentioned that they did not have data on the exclusivity of breastfeeding
All data points not collected on all participants every time (some had data collected at week eight and not 24 or vice versa)
92 HIV-positive mothers started study, 72 had final measurements (78%); 50 HIV-negative mothers started study, 46 had final measurements (92%); more were lost to follow-up in HIV-positive group
Mentioned that ideally would compare HIV-positive breastfeeding mothers to HIV mothers that did not breastfeed but that most mothers there breastfeed so could not obtain large enough sample
Six of enrolled presumably HIV-negative mothers were found to be HIV-positive and were then recategorized to that group (started out in one group then switched to the other)
Found errors in approximately 3% of the bioimpedance results (possibly due to hot and humid climate conditions).

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?		No
	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?	No
	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?		???
	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?	No
	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.)	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?		No
	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%.)	No
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	No
	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?		???
	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?	???
	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?		No
	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?	???
	7.5.	Was the measurement of effect at an appropriate level of precision?	???
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	No
	7.7.	Were the measurements conducted consistently across groups?	No
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