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

Gabrielle ShererRotation: WPNCPreceptor: 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

• 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 follow-up 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)

Control group

• No effect on walking scores over time• No changes between baseline and 6-

months 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 18-months

• 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 18-

months 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?