The Dynamic Duo: Primary Care Providers + Registered Dietitians

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April 30, 2015 by Nicholas Spence


I came across a new study by Kenneth Resnicow and colleagues in Pediatrics called “Motivational Interviewing and Dietary Counseling for Obesity in Primary Care: An RCT.”

The big question, does it it work? Yes, there was some support for the effect of motivational interviewing. Let me elaborate. This work is one of the first large scale trials demonstrating reductions in overweight children over a 2 year period by using motivational interviewing counseling on parents, delivered in a primary care setting with primary care providers and registered dietitians.

In a nutshell, this randomized clinical trial had 645 patients, aged 2 to 8 with a BMI ≥85th and ≤97th percentile, across 42 primary care practices. Random assignment was carried out across three groups with the parents: usual care; motivational interviewing with the primary care provider; motivational interviewing with the primary care provider and registered dietitian. Motivational interviewing dose was defined as moderate-intensity (4 sessions with the primary care provider; 6 sessions with the registered dietitian) over a two year period, with providers encouraged to provide more visits at the beginning of the intervention.

What was the main finding? At 2 year follow-up, BMI percentile was reduced by 4.9 for children whose parents received motivational interviewing from both primary care provider and registered dietitian. This was significantly better than the usual care group.

There were several aspects of this study that I was particularly pleased about, which prompted me to share it with you:

1) Setting – the primary care setting is highly appropriate, since it is where children have regular interaction with primary care providers, particularly during grade school;

2) Sample size of the study (statistical power) – it was conducive to testing the hypotheses adequately;

3) Dose of motivational interviewing – blanket statements that this approach does or does not “work” need to be premised by the amount that is necessary to yield an effect!

4) Related to dose, the amount (moderate-intensity) was feasible for yielding a response as well as practical in terms of administration of the intervention for this type of setting;

5) Length – 2 year follow-up. Need I say more?

6) Co-ordinated care model – diet is a central lifestyle behaviour related to bodyweight, which makes the integration of dietitians into primary care a sensible way to proceed;

7) An analysis of drop outs – yes, while we researchers hate it when it happens, those individuals do matter and can, sometimes, reveal more than the analysis of those who complete the study!

8) Acronym – BMI2 or Brief Motivational Interviewing to reduce Body Mass Index. Call me superficial, but I always appreciate a good name for a trial.

Despite the findings, before this approach can be translated into clinical practice, we need to resolve how to best train physicians and registered dietitians to use motivational interviewing in primary care, given organizational constraints such as allocated time per patient and reimbursement models, as well as how registered dietitians are ideally integrated into this setting.

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