NC: Motivational Interviewing (2008)

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

Objective: To test if basic training for dietitians in motivational interviewing (MI) resulted in changes in dietitians' counseling style and improvements in their patients' diet and risk parameters.

Inclusion Criteria:
  • Specialized diabetes-care dietitians working in nine Dutch home-care organizations
  • The dietitians requested informed consent from newly-diagnosed patients referred to them for the first time beginning September 2003
  • Enrollment of patients stopped after eight months, when a sufficient number of patients had been included.
Exclusion Criteria:
Description of Study Protocol:


  • Dietitians: 37 specialized diabetes-care dietitians working for nine Dutch home-care organizations. Recruitment took place via the home-care organizations where they worked. None of the dietitians refused to participate.
  • Client population: Recruited from newly-diagnosed patients sent to the dietitian for the first time.


  • Dietitians were randomly allocated to receive basic training in motivational interviewing
  • Data was collected among dietitians and their patients.

Blinding Used

The researcher who analyzed the transcripts of dietitian consultations with patients was blinded to whether the dietitian had been trained in MI.

Statistical Analysis

One-way analysis of variance and chi square tests were conducted to study differences in counseling style characteristics between MI dietitians and control dietitians. Baseline differences between MI patients and controls were examined with logistic regression analysies. Paired T-tests were used to explore significant differences in all patient outcome indicators between baseline and post-test.

Mulitple linear regression analyses were conducted with patients' post-test saturated fat intake, BMI, waist circumference (WC) and HbA1c level as dependent variables and group (MI=1, no MI=0) baseline level of the dependent variables, sex and age as independent variables to test the impact of MI training. Group X sex and group X age interaction effects were also analyzed in order to explore if the analyses should be stratified by sex or age group.

Data Collection Summary:

Timing of Measurements

For each participating dietitian, two consultations were tape-recorded: The first within one month after MI dietitians received their training; the second between five and six months post-baseline.

Dependent Variables

  • Motivational counseling skill analyzed from patient transcripts, using the Motivational Interviewing Treatment Integrity (MIYI) code and the Manual for the Motivational Interviewing Skill Cod (MISC), version two
  • Patients completed, at baseline and follow-up, self-administered written questionnaires on intake of saturated fat, fruits and vegetables and motivation and self-efficacy to maintain a healthful diet
  • Additionally, height and weight (to calculate BMI) and waist circumference were measured and the most recent measurement of HbA1c was recorded from the patient's record.

Independent Variables

  • Dietitians trained in motivational interviewing (MI): 18
  • Dietitians not trained: 19
Description of Actual Data Sample:

Initial N

  • Dietitians: 37
  • Patients recruited: 192.

Attrition (Final N)

  • Dietitians: N=37 (100% participation)
  • Patients: N=142 (40% refused to participate, 26% dropped out of the study).


  • Dietitians: 24 to 45 years with two to 20 years of experience
  • Patients: Mean, 59 (28 to 84).

Other Relevant Demographics

Patients: 57% had completed primary school, lower vocational training or less and 10% had college or university training.


No significant differences noted between patient groups.



Summary of Results:

Mean (SD) Scores on Motivational Interviewing (MI) Relevant Counseling Criteria in Dietitians who received MI training (MI Dietitians) or Not (Controls)

MI-Relevant Counseling Criteria (Range) First Test Second Test

MI Dietitians
Mean (SD)

Mean (SD)

(Difference Between Groups)

MI Dietitians
Mean (SD)

Mean (SD)

(Difference Between Groups)

Empathy; 1 (Low) to 7 (High)
4.6 (1.1)
4.0 (1.2)
4.4 (1.1)
3.1 (0.8)
MI spirit; 1 (Low) to 7 (High)
3.8 (1.2)
3.3 (1.5)
4.1 (1.3)
2.5 (1.1)
MI Adherence; 1 (Low to 17 (High)
9.4 (5.4)
6.6 (6.1)
6.4 (4.0)
6.9 (4.7)
MI Infidelity;1 (Low) to 17 (High)
1.2 (1.7)
3.2 (2.9)
1.6 (3.7)
3.8 (4.0)
Number of Closed Questions (2 to 31)
16.4 (7.7)
14.1 (7.6)
12.3 (6.4)
11.9 (7.0)
Number of Open Questions (0 to 12)
4.4 (3.4)
3.6 (2.9)
4.2 (3.0)
3.9 (3.0)
Total Number of Questions (3 to 38)
20.8 (8.8)
17.6 (7.9)
16.5 (8.7)
15.8 (8.7)
Number of Simple Reflections (1 to 20)
9.3 (3.7)
6.0 (4.6)
10.6 (5.0)
6.5 (3.0)
Number of Complex Reflections (0 to 5)
1.7 (2.8)
0.07 (0.8)
1.2 (1.8)
0.3 (0.6)
Total Number of Reflections (1 to 22)
10.9 (4.3)
6.9 (5.3)
11.8 (5.9)
6.8 (3.2)
Number of Change Statements (0 to 11)
2.0 (1.8)
1.6 (3.3)
3.6 (3.3)
1.1 (1.3)
Patient and Not the Dietitian Talks for the Majority of Time

Means (SD) for the Main Outcome Variables at Baseline and Posttest for Patients Counseled by Dietitians Who Either Received Motivational Interviewing Training (MI Patients) or Not (Control Patients)

MI-relevant Counseling Criterion

MI Patients (N=83)

Control Patients (N=59)

Mean (SD)

Mean (SD)


Mean (SD)

Mean (SD)


Saturated Fat Score (Points)
19.8 (6.7)
15.8 (4.9)
19.9 (6.4)
18.4 (5.5)
Vegetable Intake (g)
165 (93)
180 (109)
160 (77)
171 (84)
Fruit Intake (g)
226 (158)
261 (178)
245 (162)
247 (134)
BMI (kg/m2)
30.7 (5.7)
29.6 (5.5)
29.8 (4.3)
28.7 (4.0)
WC (cm)
105 (13)
102 (13)
107 (12)
103 (12)
8.0 (2.0)
6.7 (1.0)
7.5 (1.7)
6.5 (0.9)


Author Conclusion:
  • The present study indicates that brief training in MI can induce changes in counseling style among dietitians working in diabetes care
  • This study further shows that such training is associated with significantly larger changes in self-reported saturated fat intake scores in patients who were recently diagnosed with diabetes and therefore referred to a dietitian
  • There is no evidence that the MI training resulted in larger changes in other important diabetes-related health risk indicators, such as body mass and glycemic control, than usual care.
Funding Source:
Government: Netherlands Organization for Health Research and Development
Reviewer Comments:
  • The study was conducted in specific regions of the Netherlands
  • The sample size of diabetic patients is small (40% of eligible patients refused to participate)
  • Part of the results rely on self-report of patient measures
  • The training and evaluation of the dietitians merits further study.
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) ???
  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? ???
  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? N/A
  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