In an update to its 2012 recommendation, the U.S. Preventive Services Task Force continued to recommend that physicians not only screen for overweight and obesity, but refer adults with elevated BMI levels to behavioral intervention programs to promote weight loss and the reduction of type 2 diabetes.
The USPSTF did not offer a similar recommendation for use of weight-loss medications in partner with behavioral intervention, although it did find evidence that pharmacotherapy supported greater weight loss but with higher rates of adverse effects.
Using a baseline weight loss of 5%, which is considered “clinically important” by the FDA, the authors examined behavioral interventions that generally spanned 1 to 2 years and included at least some primary care clinician involvement, although most interventions were administered by outside professionals, such as behavioral therapists and nutritionists.
In the meta-analysis, the authors were able to confirm that the moderate benefits of behavioral interventions (weight reduction, lower incidence of type 2 diabetes development) outweighed the largely negligible harms. Using this “adequate evidence,” the USPSTF made its recommendation with a grade of “B,” which indicates a “high certainty that the net benefit is moderate” and that clinicians should provide the service or refer patients to those who can.
Evidence of behavioral
The recommendation was based on an examination of 122 randomized control studies published between 2010 and 2017. Studies were primarily concerned with weight loss and included participants older than 18 years with BMI above 25 kg/m2 (BMI > 23 kg/m2 in some studies).
Erin S. LeBlanc
Erin S. LeBlanc, MD, MPH, an investigator at Kaiser Permanente Research Affiliates Evidence-based Practice Center, Center for Health Research, and colleagues sought to answer three questions during the study. The first was whether behavioral and pharmacologic interventions improved health outcomes for people with obesity. The second focused on whether these interventions improved weight loss and weight-loss maintenance as well as the reduction of conditions commonly associated with obesity. The final question was whether there were any harmful effects of intervention.
Most of the studies did not indicate that behavioral or pharmacologic interventions had much impact on health outcomes, but the effects on weight loss and maintenance were much clearer, according to the authors. Based on the results of all studies combined, participants had a total decrease in weight of 2.4 kg (95% CI, 1.9-2.8). There was a large fluctuation in the average weight loss for each study (1.1 lb to 20.5 lb) but, generally, participants who received intervention were able to reach the 5% FDA threshold for significant weight loss.
In addition, type 2 diabetes developed less frequently among adults participating in behavior-based interventions, with two larger trials resulting in a reduction of 14.5%, according to the authors.
Fewer studies supported behavioral intervention as a substantial contributor to continued weight loss, but in the few studies for which data were presented beyond 12 months, participants tended to continue to lose weight. For all behavioral intervention trials, the authors discovered very few reports of adverse effects, although a few trials did have mixed results in relation to musculoskeletal issues.
Results of weight-loss medication trials indicated that those receiving drugs lost weight and maintained those losses when compared with control groups. Participants in weight-loss medication trials were also less likely to develop type 2 diabetes, but the authors noted several shortcomings of the studies, including high dropout and insufficient follow-up. The authors also noted that “almost all medication trials reported adverse events,” although most were not serious.
In discussing the results of their study, LeBlanc and colleagues commented on bariatric surgical interventions, which were not included as part of the USPSTF’s recommendation.
“The amount of weight loss that occurs with weight-loss surgery, however, is much greater than what can usually be achieved with behavior-based weight-loss interventions, and there are metabolic changes that occur after surgery, independent of weight loss, that could contribute to improvements in health outcomes after surgery,” the authors wrote.
Although the authors were able to determine that behavior-based weight-loss interventions were effective in promoting weight loss, maintenance and the reduction of type 2 diabetes, they were unable to identify which types of specific intervention were most effective.
“Although no two studies had exactly the same intervention messaging, schedule or mode of delivery (although many built off of learnings from earlier trials), there was consistency in the effect estimates on weight loss and precision in those estimates over time,” LeBlanc told Endocrine Today. “We could not determine to what extent specific population and intervention characteristics were driving intervention effects. To me, this suggests that the ideal counseling intervention for any given individual likely depends on consideration of his or her specific clinical characteristics and preferences.”
A ‘foundational’ recommendation
In an accompanying editorial, Susan Z. Yanovski, MD, co-director of the Office of Obesity Research, National Institute of Diabetes and Digestive and Kidney Diseases, wrote that the recommendation statement did not make substantial changes, but the inclusion of pharmacologic interventions was likely influenced by the increase in weight-loss medications on the market.
Yanovski also noted that the statement was limited by focusing only on interventions aimed only at weight loss for morbidity and mortality prevention and not on obesity-related diseases and disorders, such as diabetes.
“Although this approach may improve the specificity of the findings for patient populations without overt obesity-related diseases, it means important data on the effect of weight-management interventions among the high proportion of patients ... with such comorbidities were not considered,” Yanovski wrote. “Although intensive lifestyle intervention did not demonstrate a beneficial effect on the primary outcome of cardiovascular disease morbidity and mortality, [the Look AHEAD intervention, for example,] had salutary effects on multiple health outcomes, including sleep apnea, urinary incontinences, preservation of physical mobility, progression of chronic kidney disease, depression and physical health-related quality of life.” – by Phil Neuffer
LeBlanc ES, et al. JAMA. 2018;doi:10.1001/jama.2018.7777.
US Preventive Services Task Force. JAMA. 2018;doi:10.1001/jama.2018.13022.
Yanovski YZ. JAMA. 2018;doi:10.1001/jama.2018.11031.
Disclosures: LeBlanc reports her institution received a grant from Merck for an unrelated project on which she served as principal investigator. Yanovski reports her spouse has received research project support to his institution (Eunice Kennedy Shriver National Institute of Child Health and Human Development) from Zafgen and Rhythm Pharmaceuticals for studies of investigational products for the treatment of obesity. Please see the study for all other authors’ relevant financial disclosures.