NC: Behavior Change Strategies (2007-2008)

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

To prospectively evaluate a measure of diabetes problem-solving skill for its reliability, convergent validity, sensitivity to intervention and relationship to change in behavior.

Inclusion Criteria:
  • Female sex
  • Diagnosis of type 2 diabetes for at least six months
  • Post-menopausal
  • Living independently
  • Having a telephone
  • Ability to read English
  • Not being developmentally disabled
  • Living within 30 miles of the intervention site.
Exclusion Criteria:

None specified.

Description of Study Protocol:
  • Design: Randomized trial 
  • Blinding used: Coders of questionnaire blinded to study condition.


Mediterranean Lifestyle Program

  • Six months in duration: 2.5-day non-residental retreat, followed by weekly meetings consisting of one hour each of physical activity, stress management, Mediterranean potluck and support groups.

Statistical Analysis

  • Descriptive analyses: Means, standard deviations (SD) and distributional measures
  • Reliability analyses: Inter-rater (Pearson product-moment correlation coefficients), internal consistency (Cronbach's alpha) and test-retest reliability over six months (Pearson product-moment correlation coefficients)
  • Validity analyses
    • Correlations of problem-solving summary scores with other key measures, both unadjusted and adjusting for potential confounding variables
    • Multivariate analysis of covariance (MANCOVA) to compare post-intervention problem-sovling scores between treatment conditions, adjusting for pre-test scores, income, age and socially desirable responding
    • Hierarchical multiple-regression analyses to determine if changes in problem-sovling were related to change in validity indicators (dietary and exercise behaviors, self-efficacy) and if change in problem-solving mediated the effects of the intervention.
Data Collection Summary:

Timing of Measurements

  • Baseline
  • Six months.

Dependent Variables

  • Problem-solving skills
    • Diabetes Problem Solving Interview (DPSI): Administered as a survey
      • Participants provide written summary of how they would respond to a hypothetical barrier or problematic event in each of three sections related to diabetes regimen areas: Healthful eating, physical activity and stress management
      • Ratings from coders then summed across items to produce:
        1. Rating of overall problem-solving skill
          • Overall problem-solving rating for each situation: 1=Very poor strategy, nothing done to improve the problem situation; 5=Excellent strategy, strategies included planning ahead and flexibility.
        2. Number of different solutions proposed.
  • Dietary outcomes
    • Dietary behaviors related to fat and fiber intake; Fat and Fiber Behavior Questionnaire(FFB) (Kristal) 
    • Dietary fat intake estimate; Dietary fat screener (NCI)
    • Fruit and vegetable intake estimate; Dietary fiber screener (NCI)
    • Food frequency questionnnaire (FFQ) (Women's Health Initiative) 
    • Patient report of following a healthy eating plan; Summary of Diabetes Care.
  • Physical activity
    • Estimate of caloric expenditure; CHAMPS Activities Questionnaire for Older Adults
    • Score for regular exercise; Summary of Diabetes Self-Care Scale
    • Objective measure of caloric expenditure; seven-day record of activity and Actigraph activity monitor worn concurrently.
  • Self-Efficacy
    • Confidence in performing exercise and diet behaviors for at least six months; Sallis Self-Efficacy for Diet and Exercise Behaviors
    • Confidence in overcoming obstacles to exercise, diet and stress self-management; Confidence in Overcoming Challenges to Illness Management.

Independent Variables

Mediterranean Lifestyle Program (MLP).

Control Variables

Post-menopausal women with type 2 diabetes only.

Description of Actual Data Sample:

Initial N

  • 279 females with type 2 diabetes
  • Mean number of years since diagnosis of diabetes: Eight years; range, zero to 48 years.

Attrition (Final N)



  • Mean: 61 years
  • Range: 39 years to 75 years
  • 5% were over 70 years of age.


Caucasian: 94%.

Other Relevant Demographics

  • Mean income: $27,739; range, approximately $10,000 to $80,000
  • Education: 90% completed high school.


Mean Body Mass Index (BMI): 35.3kg per m2.


United States.

Summary of Results:

Problem Solving Scores at Baseline and Six Months
Mean (SD)


MLP Control Both Groups


Six Months


Six Months Baseline Six Months

Global Rating

3.7 (0.72)

3.9 (0.78)

3.6 (0.67)

3.6 (0.77)
3.6 (0.71)
3.8 (0.78)

Number of Strategies  

20.2 (5.3)

21.2 (5.4)

20.0 (5.1)

20.7 (5.6)
20.1 (5.3)
20.9 (5.5)

  Number of Times Employed
Top Strategies Listed Compromise


Rely on established routine or use situational prompts  
Use of willpower  
Not follow through with regimen activity
Positive self statements       
Substitute alternative activity  
Top Five Situational Obstacles Listed

Stress (217)


Physical symptoms (154)


Eating away from home (78)


Special occasions (73)


Others make it difficult (55)

  • The problem-solving global rating correlated significantly with age (R=-0.12, P=0.035). Correlations with years diagnosed with diabetes, number of other chronic diseases and socially desirable responding were not specified.
  • The problem-solving number of strategies correlated significantly with age (R=-0.14, P=0.015) and with income (R=0.20, P=0.001). Correlations with years diagnosed with diabetes, number of other chronic disease and socially desirable responding were not specified. 


  • Inter-rater reliability for a randomly-selected subset of surveys (N=114) coded by two different coders:
    • Global rating: R=0.60, P<0.001 
    • Number of strategies: R=0.86, P<0.001.
  • Six-month test-retest stability (control condition only)
    • Global rating: R=0.59
    • Number of strategies: R=0.50.
  • Internal consistency for overall problem-solving rating
    • Cronback's alpha: 0.77


Measures Problem-Solving Global Rating Problem-Solving Number of Strategies
Unadjusted R

Partial R

Unadjusted R

Partial R

Physical Activity

CHAMPS scale





Activity monitor counts


Self-monitoring of physical activity

Summary diabetes self-care activity
Dietary behavior Fruit and vegetable
Behavioral measure fat intake
Summary diabetes self care-diet

Fat intake





Self-Efficacy Sallis total score

Challenges efficacy score






Most relationships remained significant after adjusting for age, income and treatment condition.

The DPSI was sensitive to intervention effects: Scores improved significantly more in the intervention than the control condition (P<0.004).

Mediational Analysis

  • MANCOVA demonstrated that the interventon affects problem-solving significantly (P<0.004)
  • There were significant effects for all outcomes
  • There were significant effects for change in problem-solving for all outcomes , except for the CHAMPS
  • Pre-to post-change in problem-solving partially mediated the effects of the intervention on fat consumption (P<0.01) and self-efficacy (P<0.02)
  • Changes in problem-solving exerted significant effects on outcomes that were independent of the intervention effects.
Author Conclusion:
  • Results support the reliability, predictive ability and sensitivity to change of the DPSI
  • Results provide some support that people who can solve problems would be expected to feel effective in enacting self-management behaviors and those who are good problem-solvers would likely experience some success in incorporating healthy behaviors into their lifestyles
  • Use of problem-solving can add incrementally to healthy lifestyle changes beyond those that are achieved through a comprehensive diabetes intervention.
Funding Source:
University/Hospital: Arizona State
Foundation associated with industry:
Reviewer Comments:
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? 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? N/A
  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? N/A
  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%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  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? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  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? 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)? 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