Effectiveness of a motivational interviewing
intervention on weight loss, physical activity
and cardiovascular disease risk factors: a
randomized controlled trial with a 12- month postintervention follow-up
Gabrielle Sherer
Rotation: WPNC
Preceptor: Elizabeth Koustis MS RD LD
Citation
Hardcastle SJ, Taylor AH, Bailey MP, Harley RA, Hagger
MS. Effectiveness of a motivational interviewing
intervention on weight loss, physical activity and
cardiovascular disease risk factors: a randomized
controlled trial with a 12- month post-intervention
follow-up. Int J Behav Nutr Phys Act. 2013; 10: 40-56.
Background
• Traditional obesity interventions in the primary care
setting focused on changes in diet and physical activity
behaviors shown to result in clinically significant wt
reduction
– Drawbacks: intensive, require considerable financial and
human resources, often not translated to long term results
• MI intervention in studies lasting 6 mo or less shown to
result in
– Increased physical activity
– Reduced caloric intake
– Decreased BMI
Spirit of Motivational Interviewing
• Collaboration
– Practitioner is a supportive partner, not a persuasive
expert
• Evocation
– Draw out pt’s personal motives for behavior change
using their perceptions and values
– Elicit rather than impart wisdom and knowledge
• Autonomy
– Responsibility, ability, and decision to make behavioral
changes are in pt’s control
Motivational Interviewing
• Provides components that support
psychological needs
– Self-determination theory
• Linked with the enhancement of self-efficacy
– Social cognitive theory
• Linked to increasing motivational readiness to
change
– Transtheoretical model
Objective
• Assess whether changes in weight, BMI, physical
activity, and CVD risk factors within the
intervention group were maintained one-year
later.
• Explore the effect of counseling session
attendance (dose) on maintenance outcomes.
• Examine the effects of motivational interviewing
on outcomes for sub-groups presenting with
specific CVD risk factors at baseline.
Participants and Setting
• Inclusion
– 18-65 yo
– At least one CVD risk factor
• Excess weight BMI >/=28
• HTN 150/90 mmHg
• Hypercholersterolemia >/= 5.2 mmol.l-1
• Primary care health centers- UK
Design
• Baseline biochemical/anthropometric assessment conducted by trained
nurses
• All participants received a standard information leaflet on exercise and
nutrition
–
–
–
–
–
Consume five portions of fruit and vegetables per day
Recommended fat intake
Recommendation to be physically active for 30 min, five times a week
physiological and psychological benefits of increased physical activity
food and physical activity quiz with advice depending upon scores
• Intervention group: face-to-face consultation with a physical activity
specialist or registered dietician
– Opportunity to meet on up to four further occasions, for 20 to 30 mins, within
the following 6 mo
– Not encouraged to attend a certain number of sessions
• 18 months post-baseline: all participants invited to a final assessment
Intervention
• Stage Matched Approach
– Precontemplative, contemplative, preparation, action,
maitnance
• Typical strategies
– Ambivalent pts:
• agenda setting
• exploration of the pros and cons
• importance and confidence rulers
– Sufficiently motivated:
• strengthening commitment
• negotiating a change plan
Outcome Measures
• Weight, height, systolic, and diastolic blood pressure
(SBP/DBP), and fasting cholesterol
• Physical activity
– short interview version of the International Physical Activity
Questionnaire- intensity, frequency, and duration of activity in
the previous 7 days
• Physical activity stage of change
– ‘yes’ or ‘no’ answer to five questions in a flowchart format
• Fat intake
– DINE food frequency questionnaire
• Fruit and vegetable consumption
– five-a-day Community Evaluation Tool questionnaire (FACET)
Statistical Analysis
•
Satisfactory randomization
– 2 MANOVAs with behavioral and biomedical outcome variables as dependent variables and
intervention group as an independent variables
•
Effects of the MI intervention on each behavioral and biomedical outcome variable
– 3 (time: baseline vs. 6-month follow-up vs. 18-month follow up) × 2 (group: MI intervention vs.
minimal intervention) mixed-model ANCOVAs
– Bonferroni correction for multiple comparisons
– Age, gender, and smoking status entered as covariates in each model
•
Effect of number of sessions attended on change in behavioral and outcome
measures
– Hierarchical linear multiple regression analyses with number of sessions, as a continuous
independent variable
•
Effects of intervention on relevant biomedical outcome variables in groups of
participants that exhibited corresponding specific risk factors at baseline
– 3 (time: baseline vs. 6-month follow-up vs. 18-month follow up) × 2 (group: MI intervention vs.
minimal intervention) mixed-model ANCOVA
– Bonferroni correction for multiple comparisons
Results- Intervention effects
MI intervention group
Control group
•
•
•
•
•
•
•
•
Walking- increase between baseline and
6-months (p = .006, d = 0.24) and between
baseline and 18-months (p = .032, d =
0.20) -sustained change over the followup period
Stage of change- increase between
baseline and 6-months (p<. 001, d = 0.33),
returned to near baseline levels at 18
months (p <. 001, d = 0.29)
Dietary fat intake-no difference in the MI
intervention group
BMI- no significant changes
DBP- drop from baseline to 6-months (p<.
001, d = 0.29)
Cholesterol- reduced between baseline
and 6-months (p = .008, d = 0.23) maintained at 18-months (p =. 015, d =
0.22)
No effect on walking scores over time
No changes between baseline and 6months and a significant decrease
between baseline and 18-month (p<
.001, d = 0.27)
• Decrease in dietary fat intake
between baseline and 6-month
(p< .001, d = 0.43), maintained at
18 months (p< .001, d = 0.38)
• Increase in BMI between 6- and
18-month (p= .007, d = 0.21)
• No change in DBP
• increase in cholesterol between 6
and 18 months (p = .007, d =
0.30).
Results- Dose
• More sessions attended = greater reduction in
triglycerides (β = −0.20, t= −2.54, p= .012, d =
0.28)
Results- Subgroups
MI Intervention Group
• BMI in obese patients decrease in BMI between
baseline and 6-months (p =
.010, d = 0.26) /no differences
between baseline and 18months
• Cholesterol in
hypercholesterolemic
patients- decrease in
cholesterol levels between
baseline and 6-months (p =
.005, d = 0.31) and between
baseline and 18-months (p =
.003, d = 0.33)
Control Group
• Increase in BMI at 18months compared to both
baseline (p = .015, d = 0.30)
and 6-months (p = .037, d =
0.26)
• no significant changes in
cholesterol levels
Conclusions
• It is possible for a MI intervention to lead to significant
behavior changes and biomedical outcomes (inc walking
and dec cholesterol) that can be maintained for 12 months
after intervention
• Changes in the outcome variables were not associated with
the number of sessions attended-effects appear to be in
response to a relatively low dose of MI (average attendance
2 sessions)
• MI intervention can lead to a sustained decrease in BMI for
patients who were obese at baseline.
• Future research should seek to further examine the dose
effects of number of MI sessions and also elucidate the
mechanisms behind these changes
Limitations
• Low participation rate (28%)
• Important biomedical markers (insulin and
HbA1C) not measured
• Minimal practitioner training (2 four hour
training, 3 videotaped sessions)
• Self-reported measures of physical activity
and dietary intake
Clinical Implications
• Even low doses of MI can lead to some,
sustained behavioral and biochemical
improvements and can be a good alternative
to traditional prescriptive interventions.
• MI in group settings like Move?