EAL

AWM: Nutrition Education (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To describe the prevalence of nutrition label use; identify demographic, behavioral, and psychosocial correlates of label use; and examine associations of fat-related dietary behaviors, total fat, saturated fat, and fruit and vegetable intakes with use of nutrition labels in an African American population.

Inclusion Criteria:

African Americans in North Carolina, aged 20 - 70 years.

Exclusion Criteria:

Not mentioned.

Description of Study Protocol:

Recruitment

Subjects randomly selected from Dept of Motor Vehicle rosters and assigned at random to 1 of 5 different recruitment strategies based on variations of approach letters and inclusion, exclusion, or promise of a small incentive.

Design

Cross-sectional survey.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Cross-sectional survey was mailed. Subjects could also complete over the Internet or by telephone.

Statistical Analysis

Descriptive statistics were computed for nutrition label use items and demographic, behavioral, and diet-related psychosocial variables. Percentages were calculated for categorical variables and means and standard deviations for continuous variables. For each nutrition label use item, chi-square tests assessed statistically significant differences between categories of the demographic characteristics with regard to label use. To examine associations of psychosocial factors, health-related behaviors, and BMI with nutrition label use, we used logistic regression to calculate odds ratios and their 95% confidence intervals adjusted for age, sex, and education and computed P values to test for statistically significant overall differences. For ordered variables, we further assessed if there was a statistically significant linear trend. Dietary variables were not transformed because data was not skewed. Linear regression was used to estimate the variation in diet explained by label use.

Data Collection Summary:

Timing of Measurements

11-page questionnaire assessed nutrition label use, fruit and vegetable consumption, total and saturated fat intakes, fat-related dietary behaviors, diet-related psychosocial factors, and demographic and behavioral characteristics. Data collected as part of a study testing different methods and strategies to recruit African Americans into assessment of behavior risk factors for cancer.

Dependent Variables

Nutrition label use adapted from instrument developed at Fred Hutchinson Cancer Research Center
Dietary assessment: total fat and saturated fat assessed using Block fat screener and Fat-Related Diet Habits Questionnaire (developed and validated elsewhere). Fruit and vegetable consumption assessed using 7-item fruit and vegetable screener developed at National Cancer Institute.
Diet-related psychosocial factors: adapted from previous research

Independent Variables

Demographic, lifestyle, behavioral characteristics assessed: age, sex, education, marital status, smoking, current multivitamin use, urban vs rural residence, BMI classification, physical activity questionnaire

Control Variables

Description of Actual Data Sample:

Initial N: 5000 potential participants

Attrition (final N): 747 completed the questionnaire (17.5% response rate). 89 respondents did not pass eligibility and quality-control checks. Data analyzed for 658 adults (, 41% men.

Age: mean age: 43.9 +/- 11.6 years

Ethnicity: African Americans

Other relevant demographics: 37% college graduates, 75% overweight/obese (35% overweight, 40% obese)

Anthropometrics (e.g., were groups same or different on important measures)

Location: North Carolina

Summary of Results:

Other Findings

78% of respondents read nutrition labels when they purchased packaged foods: 25% read usually, 21% read often, 32% read sometimes. 22% rarely or never.

The proportion of participants reported use of specific information on the labels was similar to proportions reporting overall label use: 40% of respondents usually or often read serving size, energy, energy from fat, grams of fat, and cholesterol.

Nutrition label use was significantly higher among participants who were women (82% vs 73%, P < 0.05), older (aged 50-70 years vs 20-39 years, P < 0.05), educated beyond high school, and obese (P < 0.05).

Normal-weight respondents were about half as likely as obese respondents to read nutrition labels (OR 0.4; 95% CI: 0.2, 0.6) and energy and fat information.

SIgnificantly more women than men read serving size, energy and energy from fat information (P < 0.001). There was no statistically significant difference between men and women for reading cholesterol information.

After adjusting for demographic characteristics, the strongest psychosocial predictors of nutrition label use were healthful eating self-efficacy, strong belief in a diet-cancer relationship, and trying to lose weight.

Usual/often label readers had higher fruit and vegetable consumption and lower fat intakes (P < 0.001), and nutrition labels explained 2% to 17% of the variance in dietary intake.

Author Conclusion:

Nutrition information on packaged foods appears to be a useful way to conduct point-of-purchase nutrition education among African Americans in North Carolina. Most respondents used food labels at least sometimes, but only about half usually or often did so. Efforts should be made to determine how all consumers could use nutrition labels effectively.

Funding Source:

University/Hospital:

University of North Carolina at Chapel Hill

Not-for-profit

Foundation associated with industry:

Reviewer Comments:

Low 17.5% response rate. All data are self-report. Only certain parts of questionnaire had been validated. Not discussed why 89 respondents did not pass eligibility and quality-control check.

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?		???
	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?	???
	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?	???
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?		???
	4.1.	Were follow-up methods described and the same for all groups?	???
	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%.)	???
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	???
	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?		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?	No
	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)?	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