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Citation:

Di Noia J, Contento IR, Prochaska JO. Computer-mediated intervention tailored on transtheoretical model stages and processes of change increases fruit and vegetable consumption among urban African-American adolescents. Am J Health Promot. 2008 May-Jun;22(5):336-41.


PubMed ID: 18517094
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
POSITIVE: See Research Design and Implementation Criteria Checklist below.
Research Purpose:

To examine the efficacy of an intervention based on the transtheoretical model (TTC) for increasing fruit and vegetable consumption among economically disadvantaged African-American adolescents.

Inclusion Criteria:
  • African-American race
  • Age 11-14 years
  • Enrolled in an after-school program at a participating youth services agency
  • Informed written consent obtained from parent/guardian
Exclusion Criteria:
  • Race other than African-American
  • Age less than 11 years or greater than 14 years
Description of Study Protocol:

Recruitment

Youths were recruited from 27 youth services agencies in urban areas of New York, New Jersey and Pennsylvania.

Design   Group randomized controlled trial 

Blinding used (if applicable):  No blinding was reported

Intervention (if applicable)

  • The transtheoretical based intervention program provided youths with four 30-minute sessions of CD ROM mediated intervention content related to fruit and vegetable consumption. 
  • A staging measure built into the session classified users into precontemplation, contemplation/preparation or action/maintenance. 
  • Youths in the control arm of the study participated in regular programs offered at collaborating sites.

Statistical Analysis

  • To facilitate comparisons with prior TTM research, pro, con and self-efficacy scores were converted to standard T scores. 
  • Descriptive statistics were used to report youths' demographic characteristics, stage of change and fruit and vegetable consumption. 
  • Between arm differences in baseline measures of TTM variables and fruit and vegetable consumption were assessed using two-tailed t-tests for independent samples for continuous variables and chi-square tests for categorical data. 
  • The effects of software intervention on fruit and vegetable consumption, pros, cons and self-efficacy were examines with ANCOVA models controlled for age, gender, ethnicity and baseline measures of each outcome. 
  • Chi-square analysis was performed using posttest stage of change data for groups of youths classified by stage.
Data Collection Summary:

Timing of Measurements

Participants completed an outcome battery at pretest (two weeks before starting the intervention) and posttest (two weeks after completing the intervention)

Dependent Variables

  • Perceived pros and cons of fruit and vegetable consumption
  • Self-efficacy for fruit and vegetable consumption
  • Transtheoretical model stage of change (post-study)
  • Fruit and vegetable consumption

Independent Variables

  • Control arm vs intervention arm
  • Baseline transtheoretical model stage of change

Control Variables

  • Age
  • Gender
  • Ethnicity
  • Baseline measures of each outcome

 

Description of Actual Data Sample:

Initial N: 549 youths completed pretests

Attrition (final N): 507 youths completed posttest (61% female).  Attrition rate was 0.08%.

Age: 11-14 years

Ethnicity: African-American

Other relevant demographics: Socioeconomic status was not measured individually, however, 87% of the study participants resided in communities in which 20% or more of families had incomes below the federal poverty level.

Anthropometrics None measured

Location: Youth services agencies located in New York, New Jersey and Pennsylvania

 

Summary of Results:

Key Findings:

  • At baseline, 55% of participants were classified in contemplation/preparation, 33% in pre-contemplation and 12% in action/maintenance stages
  • After adjustment by covariates, fruit and vegetable consumption (F1, 501=26.62; p<.001) and pros of change (F1, 501=5.08; p<.025) varied significantly with the study arm
  • Youths in in computer intervention arm had higher mean intake (3.25±1.5 servings) and pro scores (51.80±9.89) than youths in the control arm (2.46±1.39 servings, 49.21±9.89 respectively)
  • Relative to youths in the control arm, greater proportions of youths in the computer intervention arm moved from precontemplation to contemplation/preparation and action/maintenance stages (13.85, p<.001) and from contemplation/preparation to action/maintenance (8.10, p<.05).  A greater proportion of youths in the computer intervention arm remained in action/maintenance following intervention than in the control arm (7.00, p<.05)
Author Conclusion:
  • Youths who interacted with the program increased their intake about 38% more than control-arm youths.  This represents an average increase of 0.9 daily servings of fruits and vegetables.
  • Computer intervention youths evidenced greater perceived pro of eating five or more daily servings of fruits and vegetables than control-arm youths.
Reviewer Comments:

Authors note the following limitations:

  • Use of a self-selected sample limits the generalizability of study findings
  • Quasi-experimental study design limits the internal validity of findings
  • Research is needed to determine the sustainability of observed effects over time

Research Design and Implementation 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 nutrition or dietetics practice?
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?
No
  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 used? (Concurrent preferred over historical controls.)
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?
N/A
  3.5. If case control or cross-sectional 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. Criterion may not be applicable in some cross-sectional studies.)
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?
No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?
No
  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.)
No
  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?
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?
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)?
No
  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
 
 

Copyright American Dietetic Association (ADA).