NC: Motivational Interviewing (2008)

Study Design:
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Quality Rating:
Research Purpose:

The aim of this randomized pilot study was to examine whether the addition of motivational interviewing strategies to a behavioral obesity intervention enhances adherence and glucose control in older obese women with NIDDM.

Inclusion Criteria:
  • Women with NIDDM
  • 50 years or older
  • Weight 120-200% of ideal.
Exclusion Criteria:
  • Taking insulin
  • Cardiovascular disease
  • Inability to walk for exercise.
Description of Study Protocol:
  • Recruitment: Advertisement and patient letter
  • Design: 22 older obese women with NIDDM were randomly assigned to one (a standard 16-week group behavioral weight-control program that provided instruction in diet, exercise and behavior modification or two) the same behavioral program with three individualized interviewing sessions
  • Blinding used: Baseline and post-treatment (four-month) assessments were conducted by trained technicians blind to group assignment
  • Intervention: Group Two had the addition of three individualized motivational interviewing sessions conducted by psychologists experienced in motivational interviewing techniques.

Statistical Analysis

  • Analysis of variance (ANOVA) and Fisher's exact test were used to determine whether the groups differed in attrition or demographic characteristics
  • Analysis of covariance (ANCOVA) was conducted to compare groups on glucose and weight, co-varying the baseline value
  • Kruskal-Wallis analysis was used to examine treatment adherence.
Data Collection Summary:

Timing of Measurements

Baseline and post-treatment (four-month) assessments.

Dependent Variables

  • Body weight was measured on a balance beam scale
  • BMI was calculated
  • GHb was collected using ion exchange liquid chromatography to assess glycemic control over the previous six to eight weeks.

Treatment Adherence

  • Attendance at group meetings
  • Number of diaries turned in
  • Number of days calories were recorded
  • Exercise frequency
  • Number of days home blood glucose was monitored.

Independent Variables

  • The 16-session group behavioral weight-control program was conducted by a team of interventionists that included a nutritionist, three psychologists and an exercise physiologist
  • Moderate calorie restriction (1,200kcal to 1,500kcal per day)
  • Fat gram recommendations (30g to 40g per day), increased physical activity, and home blood glucose monitoring were recommended
  • Weekly group meetings provided nutritional information and training in behavior modification of eating and exercise
  • Self-monitoring was a critical component of the program.
Description of Actual Data Sample:
  • Initial N: 22 women (41% black)
  • Attrition (final N): Five (16)
  • Mean age: 62.4±7.0 years
  • Ethnicity: 41% black.


  • Mean baseline BMI: 34.7±4.9
  • Average diabetes duration: 6.7±5.4 years
  • Mean baseline GHb: 10.25±2.2%.


University of Alabama at Birmingham Center for Aging.

Summary of Results:



(Measures and Confidence Intervals)

(Measures and Confidence Intervals)

Statistical Significance of Group Difference

Treatment Sessions Attended




Food Diaries Submitted




Self-Monitored Blood Glucose (days)





Reported exercise (days)
Recorded calories (days)
Glycemic control (percentage of Ghb)
Weight loss (kilograms)

*Analysis of covariance adjusted for baseline.


Author Conclusion:

The motivational group demonstrated better adherence to the program than the standard group. The motivational group had higher attendance, turned in more diaries, and monitored their blood glucose more often. Blood glucose control was significantly better in the MI group.

These pilot data suggest that the addition of motivational interviewing to a standard behavioral weight control program may significantly enhance adherence to treatment recommendations and glycemic control.

Funding Source:
University/Hospital: University of Alabama at Birmingham
Reviewer Comments:

This small pilot study suggests that motivational interviewing may enhance adherence to standard diet and exercise recommendations in older women with NIDDM.

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? ???
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.) 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? 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")? Yes
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? Yes
  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? Yes
  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)? 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