Effect of a Multidimensional Physical Activity Intervention on Body Mass Index, Skinfolds and Fitness in South African Children: Results from a Cluster-Randomised Controlled Trial

Abstract

Obesity-related conditions impose a considerable and growing burden on low- and middle-income countries, including South Africa. We aimed to assess the effect of twice a 10-week multidimensional, school-based physical activity intervention on children’s health in Port Elizabeth, South Africa. A cluster-randomised controlled trial was implemented from February 2015 to May 2016 in grade 4 classes in eight disadvantaged primary schools. Interventions consisted of physical education lessons, moving-to-music classes, in-class activity breaks and school infrastructure enhancement to promote physical activity. Primary outcomes included cardiorespiratory fitness, body mass index (BMI) and skinfold thickness. Explanatory variables were socioeconomic status, self-reported physical activity, stunting, anaemia and parasite infections. Complete data were available from 746 children. A significantly lower increase in the mean BMI Z-score (estimate of difference in mean change: −0.17; 95% confidence interval (CI): −0.24 to −0.09; p < 0.001) and reduced increase in the mean skinfold thickness (difference in mean change: −1.06; 95% CI: −1.83 to −0.29; p = 0.007) was observed in intervention schools. No significant group difference occurred in the mean change of cardiorespiratory fitness (p > 0.05). These findings show that a multidimensional, school-based physical activity intervention can reduce the increase in specific cardiovascular risk factors. However, a longer and more intensive intervention might be necessary to improve cardiorespiratory fitness.

Changes in Self-Reported Physical Activity Predict Health-Related Quality of Life Among South African Schoolchildren: Findings From the DASH Intervention Trial

“…In brief, trial schools were randomized based on a computer-generated number list either to one of four interventions or to a control condition. As described previously (29,30,48), schools were randomly allocated to one of the following intervention combinations: (i) physical activity alone; (ii) physical activity plus health and hygiene education; (iii) physical activity plus health and hygiene education plus nutrition education; and (iv) health and hygiene education plus nutrition education. Four schools served as control group and did not receive any intervention.…”

Childhood obesity intervention studies: A narrative review and guide for investigators, authors, editors, reviewers, journalists, and readers to guard against exaggerated effectiveness claims

“…64 In another case, investigators randomized one school each to 4 interventions, plus 4 no-intervention control schools. 65 A critique of the study noted that "although the number of clusters that are needed in a cluster-randomized trial is not fixed, that number is never 1," and therefore that the study "could not establish causation and, at best, only had the capacity to create the hypothesis that [the interventions] may have a favorable impact on childhood obesity." 66 In one other case, an article making similar mistakes was retracted "because the statistical analysis was not correct given the clusterrandomized design" and the "conclusion that the original paper drew about having demonstrated treatment efficacy was not supported in the corrected analysis."…”

Childhood obesity intervention studies: A narrative review and guide for investigators, authors, editors, reviewers, journalists, and readers to guard against exaggerated effectiveness claims

“…In response to a subsequent critique of the same study, the original authors published a corrigendum that continued to make invalid causal conclusions about their intervention . In another case, investigators randomized one school each to four interventions, plus four no‐intervention control schools . A critique of the study noted that “although the number of clusters that are needed in a cluster‐randomized trial is not fixed, that number is never 1,” and therefore that the study “could not establish causation and, at best, only had the capacity to create the hypothesis that [the interventions] may have a favorable impact on childhood obesity.” In one other case, an article making similar mistakes was retracted “because the statistical analysis was not correct given the cluster‐randomized design” and the “conclusion that the original paper drew about having demonstrated treatment efficacy was not supported in the corrected analysis.”…”