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Motivational interviewing not effective to address obesity in one study; expert says findings will help improve tool

January 29, 2024

A new study did not find benefit in using motivational interviewing to help children with overweight and obesity. Authors called the findings “unexpected” and said they could be due to patient characteristics, study methods and the COVID-19 pandemic.

An AAP expert said studies showing a positive impact from motivational interviewing still outnumber the negative, and the new findings will help tailor the tool to make it more effective.

“It poses questions that need to be posed,” said Sandra G. Hassink, M.D., FAAP, medical director of the AAP Institute for Healthy Childhood Weight. “Because (motivational interviewing) is a methodology that I think is important to pediatricians, has helped pediatricians and patients … we need to understand how to tailor and individualize it and get it to work the best way possible.”

Motivational interviewing (MI) is an important component of the 2023 AAP clinical practice guideline on obesity, where it is described as a “patient-centered counseling style” that “guides families to identify a behavior to change, based on what the parent(s) or child feels is important and can be accomplished.” Dr. Hassink, an author of the guideline, said the tool has been “illuminating and practice-changing.”

“It’s a dialogical tool that allows you to partner with the patient in a very empowering, I think, and compassionate way to get to goal setting and solutions that work for the patient,” she said.

Still, the guideline acknowledges that while studies have found it to be successful, “much more work is needed to examine optimal characteristics that might moderate MI’s impact.”

In the new study "Outcome of BMI2+: Motivational Interviewing to Reduce BMI Through Primary Care AAP PROS Practices" (Resnicow K, et al. Pediatrics. Jan. 29, 2024), researchers tested motivational interviewing with 18 practices from the AAP Pediatric Research in Office Settings network from 2017 through 2021. Half were randomized to use a motivational interviewing intervention, and the other half provided usual care. Children in the study were ages 3-11 years who had overweight or obesity but did not have diabetes, severe medical disorders or medications that would affect their growth.

The motivational interviewing intervention consisted of in-person/telehealth counseling by pediatric clinicians, phone sessions with a registered dietitian, parent education materials, and text message reminders and tailored motivational messages.

The intervention addressed the health risks associated with obesity, the benefit of healthy eating and physical activity and how to implement healthier eating habits. It focused on changing behaviors with small goals that could be built upon, not restricting calories or meeting dietary or activity guidelines.

Children in the intervention were matched based on age and gender to three children from a usual care practice. Over two years, children in the intervention group gained more relative weight for their age and sex than the usual care group. The intervention group had an absolute excess weight gain of about 0.5 body mass index (BMI) units or about 1 kilogram compared to the usual care group.

Authors said the weight gain was “small” but “nonetheless statistically significant and unexpected.” They found a negative effect specifically among Black children and children who identified as a race other than Black, white or Hispanic.

Authors said while it is possible motivational interviewing is ineffective for this age group, there are numerous other explanations for the tool having no effect for some and a negative effect for others. Some patients may have needed more counseling sessions with a pediatric clinician or registered dietitian. The average number was about 4.5 over two years while protocols called for 10. However, those in the group with higher numbers of sessions did not seem to fare better.

Youth in the intervention group also had a higher BMI at baseline than the comparison group. Racial differences between counselors and patients also could have impacted the efficacy of the counseling. In addition, children gained extra weight during the COVID-19 pandemic, especially Black and Hispanic youths as well as those who already had obesity.

“More broadly, this study suggests that the model used needs reconfiguration," authors wrote. "The required dose to achieve weight effects may be unattainable in our current healthcare delivery system."

Going forward, authors suggested trying different approaches, including more digital interventions, greater fidelity to the principles of motivational interviewing, using different counselors and more structured programs.

Dr. Hassink agreed that many of the factors the study cited could have a significant impact on the results. She said obesity is complex, and patient characteristics like obesity severity, comorbidities, experiences of weight bias, how quickly a patient has been gaining weight and patient motivation all could impact how well motivational interviewing works.

“To me, the studies that don’t come out as expected are the studies that prompt us to say ‘let’s find out more about what happened. Let’s design a study that maybe gets more granular. Let’s move on from here, let’s not just walk away, let’s keep moving and try to understand why certain MI studies turn out negative and some do not,’” she said. “I think that will ultimately increase the usefulness of a tool we all feel is a worthwhile tool for obesity treatment.”

 

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