EAL

H/A: Monitoring of Food Intake (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The study aimed to compare the estimated nutrient intake of HIV-infected adults using two different dietary assessment methods: Block's Food Frequency Questionnaire and three-day food records.

Inclusion Criteria:

Inclusion criteria included:

Older than 18 years of age
HIV-positive
Consented to participate.

Exclusion Criteria:

Participants were excluded if:

Pregnant at time of recruitment
Diagnosed with diabetes mellitus
Had thyroid disease or other malignancies
Not fluent in English.

Description of Study Protocol:

Recruitment

Participants were recruited for the Nutrition for Healthy Living Study. Details of recruitment for this study were not provided.

Design

Longitudinal cohort study.

Statistical Analysis

Comparisons between dietary assessment methods were determined using deattenuated Pearson correlation coefficients, median of individual differences in intake, quintile rankings and percentage less than Dietary Reference Intakes (DRIs) using McNemar test
Nutrient intakes were adjusted for total energy using the residual method.

Data Collection Summary:

Timing of Measurements

Measurements were taken at baseline, six months after enrollment and at 12 months after enrollment, with the exception of the food frequency questionnaire (FFQ), which was administered once at 12 months after enrollment because it elicits dietary intake for the preceding 12 months.

Dependent Variables

Dietary intake was measured by three-day food records taken at baseline, six months and 12 months after enrollment and Block's Food Frequency Questionnaire taken at 12 months after enrollment
Serum folate taken at 12 months after an eight- to 12-hour fast using the ACS-180-Folate assay
Body mass index (BMI) calculated using standard measurements of height and weight.

Independent Variables

HIV infection
Demographic variables including race (white or non-white), education (less than high school or more than high school) and housing insecurity, defined as living in a shelter, rooming or boarding house, residential treatment facility or on the streets.

Control Variable

Adjusted for total energy intake.

Description of Actual Data Sample:

Initial N

469.

Attrition

315 (244 males, 71 females) after exclusion for:

Food records were not deemed complete or acceptable
Had not completed FFQ
Had missing dietary intake data.

Age

Participants were grouped by sex:

Mean age among males was 42±8 years
Mean age among females was 39±7 years.

Ethnicity

Not available.

Other Relevant Demographics

Housing insecurity: 6% of male participants had insecure housing, compared with 9% of females
Education: 9% of males reported less than high school education, compared to 23% of females
Mean CD4 count: Men, 380±241 cells per mm³; women, 467±307 cells/mm³.

Anthropometrics

Mean BMI: Men, 42±8; females, 39±7
Statistical difference between both groups was not reported.

Location

Boston, MA.

Summary of Results:

Comparison of the Two Methods Via Median Intakes

Median reported intakes of all macronutrients and most micronutrients were significantly less on the FFQ for both men and women
The FFQ estimated significantly less calorie (P<0.001), fat (P<0.001), protein (P<0.001) and carbohydrate (P<0.001) intakes, compared with the food record. The difference was greater among men in all three macronutrients.
All other nutrients, with the exception of folate, vitamin A, vitamin E, vitamin C, zinc and alcohol, were estimated significantly less via the FFQ by more than 20%.

Correlation Coefficients

Among men, the largest correlation coeffcient between the two methods was observed for alcohol (R=0.66; P, N/A)
Among women, the largest correlation coefficient was observed for fiber (R=0.53; P, N/A).

Ability to Rank Subjects by Quintile

Mean percentage agreement between the methods to rank individuals was 30%.

Percentage of Subjects Less than Dietary Recommended Intakes

Among males, the FFQ estimated significanlty more participants as having intakes less than the DRI for all nutrients examined except vitamins A and C
Among females, the FFQ estimated significantly more participants as having intakes less than the DRI for protein, (P<0.001), thiamin (P<0.001), riboflavin (P<0.001), niacin (P<0.001) and iron (P<0.001).

Other Findings

Being white was significantly associated with a greater difference between the two methods in fat (P<0.05), alcohol and vitamin A (P<0.01)
Serum folate as a biomarker to validate both dietary assessment methods indicated there was a significant relationship with folate calculated via three-day food records (R=0.25; P=0.016).

Author Conclusion:

Although all dietary methods remain imperfect, we believe the limited degree of detail in types of foods, portion sizes and prompts in the Block FFQ lead to a significant difference in estimated intakes, compared with food records in this cohort of individuals living with HIV infection.

Funding Source:

Government:

National Institute of Health

Reviewer Comments:

This was a very well-conducted study that aimed to compare two dietary assessment methods among individuals living with HIV infection. The comparison is made between the mean nutrient intake estimated from three different three-day food records and one FFQ. It is therefore assumed that three different three-day food records six months apart is representative of an individual's food intake in the previous year. This assumption is the basis of the comparison between the two methods because the FFQ aims to capture an individual's usual intake in the previous year.
Because the population being studied may have greater variability in dietary intake due to medications and other factors also mentioned by the authors, it may be more difficult to establish usual dietary intake.

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?	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?	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")?	Yes
4.	Was method of handling withdrawals described?		Yes
	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%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	Yes
	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?		N/A
	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?	N/A
	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?	No
	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