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Adult Weight Management

AWM: Nutrition Education (2006)

Citation:

Kreuter MW, Brennan LK, Scharff DP, Lukwago SN.  Do nutrition label readers eat healthier diets?  Behavioral correlates of adults' use of food labels.  Am J Prev Med 1997; 13(4): 277-283. 

PubMed ID: 9236964
 
Study Design:
Cross-Sectional Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To identify characteristics of adult primary care patients who do and do not read nutrition labels, to describe patterns of label use and perceptions of label understandability among those who read nutrition labels, and to identify behavioral and health status correlates of nutrition label reading.
Inclusion Criteria:
18 years or older, without visible physical or mental limitations.
Exclusion Criteria:
None specifically mentioned.
Description of Study Protocol:

Recruitment

Patients from 4 family medicine clinics in 3 towns.  Clinics selected based on their comparatively high patient volume for the region.

Design

Cross-Sectional Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Patients completed a self-administered survey while waiting to see physicians.

Statistical Analysis

Bivariate analyses using chi-square tests were conducted with 5 demographic and 8 health status variables as predictors.  Separate logistic regression analyses conducted to identify differences in characteristics of those reading elements of nutrition label.  Analyses included all demographic variables as predictors, and each label element as a dependent variable.  Logistic regression also used to detemrine whether patients focused on elements of label relating most closely to own health risks and dietary patterns.

Data Collection Summary:

Timing of Measurements

Questionnaires completed during a 2-week data collection period.

Dependent Variables

  • Multi-item assessments of 4 health-related behaviors:  cigarette smoking, physical activity, dietary fat consumption, and nutrition label reading.  For each behavior, patient's level of risk, readiness to make changes, and factors that could influence the ability to make changes were assessed.
  • For nutrition label reading, frequency of label use, elements of label most commonly used, labels' influence on food purchases, and the ease or difficulty of understanding nutrition labels was assessed 

Independent Variables

  • Demographic and health status variables also assessed, including age, gender, race, education, marital status, height, weight, blood pressure, cholesterol, and personal and family history of heart disease 
  • Consumption of dietary fat, fruits, vegetables and fiber assessed using brief 24-item food frequency screener, which has been shown to be reasonably valid for assessing dietary fat intake

Control Variables

 

Description of Actual Data Sample:

Initial N: 915 questionnaires collected.

Attrition (final N):  885 questionnaires in final sample, 73.9% female.  30 were disqualified due to extensive missing data.

Age: mean age of 49 years

Ethnicity: 96.4% Caucasian

Other relevant demographics:

Anthropometrics 

Location:  Southeastern Missouri 

 

Summary of Results:

Other Findings

80% of patients reported having read nutrition labels in the past 12 months.  Females were more likely to have read labels (86% vs 67%, P < 0.0001), as were those with more years of education (P < 0.0001), diets lower in fat (P < 0.001), accurate perceptions of their own dietary fat consumption (P < 0.0001), and whose doctors had recommended that they eat less fat (P < 0.01).

More frequent use of labels was also associated with healthier dietary practices - those whose diets were lower in fat and higher in fruits, vegetables and fiber were much more likely to report reading labels most or all of the time.

Among those who had read labels in past 12 months,  23% felt that they were "very easy" to understand and 65% felt that they were "fairly easy". 

Patients eating diets lower in fat were more likely (51% vs 26%) than patients whose diets were higher in fat to report labels influencing their food purchase decisions, as were patients eating diets higher in fruits, vegetables and fiber (both P < 0.0001).

Among all patients reading labels in past 12 months, 84% looked for information on fat, 68% on calories, 48% on saturated fat, 45% on cholesterol, 45% on sodium, and 21% on fiber.

Women were 33% more likely than men to look for calories (OR = 1.33, 95% CI: 1.09. 1.62) and 44% more likely to look for total fat (OR = 1.44, 95% CI: 1.13, 1.84).

Patients with high blood pressure were 63% more likely than those with normal or low blood pressure to look for sodium on the nutrition label (OR = 1.63, 95% CI: 1.35 - 1.97) but no more likely to look for other nutrition label information.

Similarly, patients with high cholesterol were more likely than those with normal or low cholesterol to look for saturated fat (OR = 1.39, 95% CI: 1.13, 1.72) and cholesterol (OR = 1.60, 95% CI: 1.29, 1.98) on the label, but no more likely to look for other nutrition label information.

Author Conclusion:
Findings consistently supported a relationship between patients' label reading and their dietary practices.  In this study, patients whose diets were lower in fat and higher in fruits, vegetables and fiber reported reading nutrition labels more often than patients whose diets were higher in fat and lower in fruits, vegetables and fiber.  These data also suggest that persons suffering from diet-related health problems may use nutrition labels as a means of identifying foods appropriate for managing their condition.
Funding Source:
Government: CDC
Reviewer Comments:
Dietary intake instrument shown to be valid.  Fairly representative of region.  Large sample size.
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) 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? 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? 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? Yes
  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? Yes
  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)? 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