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Natural BMI reduction could confound obesity trial efficacy
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Accounting for the natural tendency for BMI to fall slightly in children with overweight could prevent implementation of interventions unlikely to alter the course of the obesity epidemic, according to research published in Pediatrics.
“Scaling even low-intensity interventions to the population is not only costly but may subsequently impede more effective interventions because of competing workforce demands and/or the challenges of decommissioning services that may erroneously be perceived as beneficial,” the researchers wrote.
Melissa Wake, MD, of the University of Melbourne, Australia, and colleagues summarized BMI z score changes in community samples of children aged 5 to 10 years with overweight and/or obesity, based on International Obesity Task Force cut points, from four Australian studies.
The researchers pooled person-level data from the observational Longitudinal Study of Australian Children (LSAC, n=1,816), along with the randomized Live, Eat and Play (LEAP) trials 1 (n=146) and 2 (n=242) and Shared-Care Obesity Trial in Children (HopSCOTCH, n=77); the trials had a retention rate between 89% and 94%.
Change in BMI z scores was reported both continuously and categorically (% revealing any, ≥0.25 and ≥0.5 reductions) during a 15-month period to ensure 12 months of follow-up.
BMI z scores decreased slightly with time in all six continuous analyses (overweight, obese and overweight/obese groups for the observational and intervention studies separately).
Mean changes were smaller in the observational study (–0.05 to –0.1) than the intervention studies (–0.12 to –0.14), but individuals varied markedly. In the observational study, approximately 62% showed any BMI z score reduction, with 16% falling by at least 0.25 and 4% by at least 0.5. In the intervention studies, 68% showed any reduction, with 30% falling by at least 0.25 and 11% by at least 0.5.
“The natural tendency for high BMI z scores to fall somewhat could even be heightened in tertiary clinics because one might expect (and our analyses confirm) larger natural improvements in treatment than observational studies, and in obese than overweight children,” the researchers wrote.
The researchers make recommendations to maintain adequate trial control and assess health gains and improvements over the long term.
Disclosure: The researchers report no relevant financial disclosures
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