Childhood obesity prevention trials: A systematic review and meta-analysis on trial design and the impact of type 1 error.

Louise Padgett, June Stevens, Carolyn Summerbell, Wendy Burton, Elizabeth Stamp, Laura McLarty, Holly Schofield, Maria Bryant

Journal: Obesity reviews : an official journal of the International Association for the Study of Obesity 2024;25(6):e13736

PMID: 38529530

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Plain Language Summary

Individuals living with over-weight or obesity as a child are more likely to have overweight or obesity in adulthood and as a result suffer from obesity-related chronic diseases and, as recently shown, death from infectious disease such as Covid-19. The primary aim was to systematically review and analyse the design of childhood obesity prevention randomised controlled trials and assess how type 1 error [(false-positive) occurs if an investigator rejects a null hypothesis that is actually true in the population] influences their reported effectiveness. This study was a systematic review and meta-analysis of eighty-four randomised controlled trials. Results showed that there is broad variation in the design of child obesity prevention trials and that the effectiveness of obesity prevention interventions is being determined according to a range of expected effect sizes. In fact, when accounting for type 1 error, the effectiveness of several interventions was reduced, highlighting the importance of rigorous trial design and statistical analysis. Authors concluded that while many childhood obesity prevention trials report positive outcomes, the lack of control for type 1 error, can lead to inflated effectiveness estimates. Thus, they emphasise the need for more robust trial designs and statistical methods to ensure accurate and reliable results in obesity prevention research.

Abstract

Effect sizes from previously reported trials are often used to determine the meaningful change in weight in childhood obesity prevention interventions because information on clinically meaningful differences is lacking. Estimates from previous trials may be influenced by statistical significance; therefore, it is important that they have a low risk of type 1 error. A systematic review and meta-analysis were conducted to report on the design of child obesity prevention randomized controlled trials and effectiveness according to risk of type 1 error. Eighty-four randomized controlled trials were identified. A large range of assumptions were applied in the sample size calculations. The most common primary outcome was BMI, with detectable effect size differences used in sample size calculations ranging from 0.25 kg/m (followed up at 2 years) to 1.1 kg/m (at 9 months) and BMI z-score ranging from 0.1 (at 4 years) to 0.67 (at 3 years). There was no consistent relationship between low risk of type 1 error and reports of higher or lower effectiveness. Further clarity of the size of a meaningful difference in weight in childhood obesity prevention trials is required to support evaluation design and decision-making for intervention and policy. Type 1 error risk does not appear to impact effect sizes in a consistent direction.

Address: Department of Health Sciences, University of York, York, UK.; Department of Nutrition, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA.; Department of Sport and Exercise Sciences, Durham University, Durham City, UK.; School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.; Leeds Institute for Clinical Trials Research, University of Leeds, Leeds, UK.; Department of Health Sciences and the Hull York Medical School, University of York, York, UK.

DOI: 10.1111/obr.13736