NC: Motivational Interviewing (2008)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

This study reports on Eat for Life, a multi-component intervention to increase fruit and vegetable consumption among African-Americans, that was delivered through black churches.

Inclusion Criteria:

Adult members (over 18 years old) of 14 black churches in the metropolitan area of Atlanta, GA, matched by socioeconomic status (low, mixed or high) and size.

Exclusion Criteria:

None noted.

Description of Study Protocol:


  • 14 black churches in Atlanta, GA
  • In each church, a liason was hired to assist in the recruitment and retention of participants
  • Pastors were asked to encourage congregants to attend health fairs held immediately after Sunday services
  • Flyers were posted and announcements were placed in church bulletins. 


14 churches were randomly assigned to three treatment conditions.


  1. Comparisons
  2. Self-help intervention with one telephone cue call
  3. Self-help with one cue call and three counseling calls. The telephone counseling in Group Three was based on motivational inteviewing.

Statistical Analysis

  • The primary outcome, assessed at baseline and one-year follow-up, was fruit and vegetable intake as assessed by three food frequency questionnaires
  • Outcomes were analayzed with a mixed-model, repeated-measures, analysis of variance program that allows for adjustment of the clustering of measurements within churches.
Data Collection Summary:

Timing of Measurements

Baseline and one-year follow-up.

Dependent Variables

  • Diet: Multiple measures of dietary intake
    • Seven-item food frequency questionnaire
    • Two-item measure to assess usual fruit and vegetable intake
    • 36-item fruit and vegetable FFQ.
  • Psychosocial meaures
    • Outcomes expectations for fruit and vegetable intake were assessed with a 19-item scale
    • Self-efficacy to eat more fruits and vegetables was assessed with a 10-item scale
    • Low-fat and high-fat vegetable preparation practices were assessed
    • Portion size knowledge was measured with an eight-item index that assessed awareness of standard serving sizes for fruits and vegetables.
  • Other variables assessed
    • Household income was assed with an eight-category ordinal item
    • Education, work status, marital status, use of cigarettes and alcohol in the previous 30 days were assessed
    • Church involvement was assessed with a single open-ended question
    • Exercise was assessed with a single open-ended question
    • Use of vitamin supplements in the past year was assessed with a single item with three categories.

Independent Variables

  • Self-help intervention with one telephone cue call
  • Self-help with one cue call and three counseling calls.

Control Variables

Comparison group.

Description of Actual Data Sample:
  • Initial N: 1,011
  • Attrition (final N)
    • Dropouts: N=150
    • Cohort: N=861 (15% attrition).
  • Age: Mean age of 44
  • Ethnicity: Black.

Other Relevant Demographics

  • 73% female
  • 54% were married or living with a partner
  • 45% reported an income of $40,000 or more
  • More than half had at least some college education.


Atlanta, GA.

Summary of Results:

Baseline and Post-Test Mean Numbers of Fruit and Vegetable Servings per Day

  Group One Group Two Group Three P-Value
Two-Item FFQ

Baseline: 3.50
Post-test: 3.76

Baseline: 3.77
Post-test: 4.27

Baseline: 3.46
Post-test: 5.10

P<0.01 between 1 and 3
P<0.01 between 2 and 3

Seven-Item FFQ

Baseline: 3.18
Post-test: 3.52

Baseline: 3.76
Post-test: 4.03

Baseline: 3.44
Post-test: 4.81

P<0.01 between 1 and 3
P<0.01 between 2 and 3

36-Item FFQ

Baseline: 4.43
Post-test: 4.52

Baseline: 4.46
Post-test: 4.79

Baseline: 4.32
Post-test: 5.62

P<0.01 between 1 and 3
P<0.01 between 2 and 3

Mean of Three FFQs

Baseline: 3.64
Post-test: 3.91

Baseline: 3.97
Post-test: 4.38

Baseline: 3.78
Post-test: 5.17

P<0.01 between 1 and 3
P<0.01 between 2 and 3

Other Findings

  • Across the three FFQs, the change in fruit and vegetable intake was largest in Group Three
  • For fruits, vegetables and fruits-plus-vegetables, interaction terms for sex, age, education and income with treatment group were all non-significant
  • Low-fat vegetable preparation practices improved significantly in Group Three
  • There were no significant effects for knowledge of portion size, self-efficacy, outcome expectations or high-fat practices
  • Individuals in Group Three were significantly more likely to report using the cookbook and marginally more likely to report watching some or most of the videos.
Author Conclusion:
  • Motivational interviewing appears to be a promising strategy for modifying dietary behavior
  • Black churches are an excellent setting to implement and evaluate health promotion programs.
Funding Source:
Government: National Cancer Institute
Reviewer Comments:
  • This project used dietitians trained in motivational interviewing techniques
  • This is promising research.
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? ???
  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? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  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")? 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? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? ???
  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? 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? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  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? Yes
  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)? N/A
  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