EAL

H/A: Monitoring of Food Intake (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The purposes of the study were to:

Determine prevalence of obesity among HIV-infected individuals
Identify differences in dietary intake among individuals classified as having a normal weight, overweight or obese
Identify differences in insulin resistance among individuals classified as having a normal weight, overweight or obese.

Inclusion Criteria:

Participants in the study were:

Adults with HIV infection enrolled in the Nutrition for Healthy Living cohort study
Living in the Boston, MA and Providence, RI, area.

Exclusion Criteria:

Exclusion criteria included:

Pregnancy at the time of enrollment
Presence of thyroid disease, malignancies or Kaposi's sarcoma
Presence of diabetes
Had not completed a three-day food record
Body mass index (BMI) less than 20.

Description of Study Protocol:

Recruitment

Participants were enrolled in the Nutrition for Healthy Living Study.

Design

Cross-sectional study. Participants were stratified into three groups according to BMI category:

Group One: BMI 20 to 24.9
Group Two: BMI 25 to 29.9
Group Three: BMI over30.

Each group was further stratified by sex.

Statistical Analysis

One-way analysis of variance using Bonferroni correction was used to determine statistical difference among BMI categories
Logarithmic transformation was done with skewed distributions from micronutrients and insulin resistance measures.

Data Collection Summary:

Timing of Measurements

The data analyzed were from the most recent visit of the participants actively enrolled in the cohort between September 21, 2000 and October 27, 2003.

Dependent Variables

BMI was calculated from standard measures of height and weight
Food intake was measured using a three-day food record
Insulin resistance was estimated using the homeostatis model assessment and the quantitative insulin sensitivity check index
Resting energy expenditure (REE) was calculated using indirect calorimetry by oxygen and carbon dioxide exchange rates using the Weir equation
Waist circumference was done by standard measures
Arm muscle circumference was calculated by standard measures
Fat mass and fat-free mass was determined using bioelectric impedance resistance and reactance
Physical activity was assessed by self-report of strength training.

Independent Variable

HIV infection.

Description of Actual Data Sample:

Initial N: 321 (265 men, 56 women)
Attrition (final N): 321
Age: Mean age was calculated separately according to BMI group and sex. Among men, mean age was between approximately 44 to 46 years. Among women, mean age was approximately 39 to 43 years across BMI groups.
Ethnicity: Not reported.

Anthropometrics

Waist circumference (cm) in men

Group One: 85.4±5.7
Group Two: 95±6.7
Group Three: 109.5±7.0.

Waist circumference (cm) in women

Group One: 80.5±7.1
Group Two: 90.7±6.4
Group Three: 101.7±16.8.

REE

Among men, there was a significant difference in REE across the three groups.

Group One: 1,802±262
Group Two: 1,905±242
Group Three: 2,069±231.

Among women, REE was significantly greater in Group Three than the other groups.

Group One: 1,512±209
Group Two: 1,478±193
Group Three: 1,788±335.

Location

Boston, MA.

Summary of Results:

Prevalence of Overweight and Obesity Among Sample

Males (N=265)

Normal weight: 47.9%
Overweight: 39.6%
Obesity: 12.5%.

Females (N=56)

Normal weight: 37.5%
Overweight: 33.9%
Obesity: 28.6%.

Correlates of BMI

Among males, shorter duration of known HIV, trying to lose weight and non-white race were associated with higher BMI (P<0.05)
Women with BMI more than 30 were more likely to be non-white (P<0.01).

Dietary Intake Across Groups

Energy per kilogram of body weight was significantly different across groups for both males and females
Vitamin B₁₂ was significantly different across groups
Total energy intake decreased as BMI increased among women.

Other Findings

Comparisons of dietary intake with measures of REE by indirect calorimetry suggest women under-reported their dietary intake in the three-day food records
Although not different between groups, mean total fat and saturated fat intakes were more than recommendations for both men and women in all BMI categories, whereas total grams of dietary fiber decreased as BMI increased
Individuals in all BMI groups had micronutrient intakes less than the Dietary Reference Intakes
Serum markers of insulin resistance were significantly different by BMI category among men and women, as were triglycerides and total cholesterol for the men.

Author Conclusion:

Obesity in this population needs to be addressed because quality of dietary intake may have future implications regarding cardiovascular disease, metabolic syndrome and other risks associated with overweight and obesity.

Funding Source:

Government:

National Institute of Health, General Clinical Research Center

Reviewer Comments:

This was a very well-conducted cross-sectional study that used data from a larger longitudinal study that examined the metabolic and nutritional consequences of HIV infection. The measures used were reliable and standard procedures were described for all measures assessed in the study. Limitations and main results were thoroughly discussed.

One of the objectives of the study was to determine prevalence of obesity among the sample stratified by sex, yet the sample of women was small (N=56). The authors did not report statistical significance for all results relevant to the study, such as the association of variables significantly associated with greater BMI. Demographic characteristics of the sample were vague, not indicating ethnicity or race of the sample. However, the results section indicates non-white women were more likely to have greater BMI.

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)	Yes
	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)	Yes

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?	No
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.)	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?		N/A
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	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%.)	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	N/A
	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?		No
	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.)	N/A
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	No
	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?	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)?	No
	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?	No
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