Grandparents Central to Success of Obesity Prevention in Chinese Kids

Becky McCall

December 04, 2019

An obesity prevention scheme significantly reduces body mass index (BMI) by working with primary school children, parents, and notably grandparents, show results from one of the largest trials of obesity prevention in children in the world.

Known as the Chinese Primary School Children Physical Activity and Dietary Behavior Changes Intervention (Chirpy Dragon), the randomized controlled trial is the first to place grandparents central to obesity prevention and is the end result of a decade of work looking at the cultural and behavioral impact of grandparents on children's body weight in China.

Bai Li, MD, who currently holds a position at the University of Bristol, UK, conducted the study in the city of Guangzhou.

"This evidence-based obesity intervention program delivered by school and family had a high level of delivery adherence and participant engagement, and may be effective in reducing the emerging epidemic of childhood obesity in China," she remarked. 

After 1 year the zBMI score (a BMI of relative weight adjusted for child age and sex) was significantly lower in the intervention than the control group, with a mean between-group difference of –0.13.

"The latest Cochrane review of childhood obesity prevention programs around the world shows that the pooled mean effect size across all interventions targeting the same age group is –0.05, but our results are over twice as high as this effect size," said Li, explaining the practical significance of the finding.

She added that the program was also good value for money, as shown by the cost-effectiveness evaluation that was also conducted.

The study was published online November 26 in PLoS Medicine.

China's Unprecedented Rate of Increase in Childhood Bodyweight

Currently, there are around 30 million children aged 7 to 18 years who are overweight or obese in China, a figure that is equivalent to one fifth of the world's child population with overweight/obesity. Without effective prevention programs, this figure is estimated to increase to around 50 million by 2030.

Li explained to Medscape Medical News that it is the rate of increase that worries her most. "In the 1980s, less than 1% of children were overweight, now 30% are overweight in the most affluent regions of China. It is the rate of increase that is a big concern."

The rapid escalation in prevalence, combined with a lack of scientifically robust research in this field in China, motivated Li to start Chirpy Dragon. The researcher is particularly interested in the cultural barriers and drivers to the fast-growing nature of the country's obesity problem.

"Genes don't change, but the environment has changed. With respect to childcare, grandparents are important all over the world, but in China, it is common to see three generations living in one household and having a direct influence on diet and nutrition," she explained.

The older generation today grew up in a time of food poverty, which informed their understanding of what comprises a healthy diet and weight, she added.

"Now this generation find themselves living in a time of disposable income and a Western diet, and many grandparents believe that the bigger the child, the healthier the child, and that [overweight/obesity] is a sign of wealth," explained Li.

Chirpy Dragon Intervention for Children, Parents, and Grandparents

The 12-month randomized controlled trial was aimed at prevention, not treatment, and promoted physical activity and healthy eating behaviors. The study involved 1641 children who were 6-years-old from 40 schools across Guangzhou. Twenty schools (832 children) were allocated to the intervention and 20 schools (809 children) to usual care.

Four school- and family-based components targeted children, main carers (parents or guardians and grandparents), as well as those responsible for school-based physical activity and food provision.

Interventions were tailored to the target group. "We might put raw ingredients in front of parents and grandparents and then ask them how they plan and balance a healthy meal," explained Li.

"For the schools, we worked with local meal providers to determine what is feasible according to the season and the cost involved. We also wanted to create the opportunity for physical activity without the need for special equipment," she said.

Chirpy Dragon staff delivered the intervention and school heads and class teachers received a program handbook.

Schools assigned to the control arm continued with their usual provision during the full trial period and had no access to any of the Chirpy Dragon intervention activities and resources.

Blinded measurements were taken and included zBMI score at baseline (school entry, age 6-7 years) and again at intervention end (after 12 months).

Positive Findings for Intervention on All Outcomes

The primary outcome for clinical effectiveness was the difference in zBMI scores between groups at study completion.

Among the secondary outcomes were the proportion of children with overweight or obesity, time spent in physical activity, consumption of fruit and vegetables and unhealthy snacks, as well as wider psychosocial effects comprised of health-related quality of life and social acceptance.

The participant drop-out rate was very low, at 3%, and no schools dropped out.

At intervention end, the mean zBMI score was significantly lower in the intervention compared with the control group (mean difference, −0.13; P = .048).

For the secondary outcomes, the proportion of children consuming at least five daily portions of fruit and vegetables was significantly higher in the intervention than the control group (mean difference, 0.33; P = .001).

Weekly consumption of sugar-sweetened beverages and unhealthy snacks was significantly lower in the intervention than the control group (mean difference, −0.81; P = .010), and the proportion of children engaging in physical activity at least once at the weekend was higher in the intervention versus the control group (odds ratio, 1.58; P < .001).

A prespecified subgroup analysis found that the intervention effect on anthropometric measurements was more marked in girls compared with boys. The mean difference in zBMI score in girls versus boys was −0.18 (P = .007) versus −0.09 (P = .22).

Why Were Results So Impressive?

Asked to comment on the reasons for such strongly positive findings, Li said a number of factors could be at play.

She drew comparison with a recent similar UK trial, which in contrast, had virtually no impact.

"We believe the difference is partly related to the stage of the epidemic in China. [It] is relatively early compared with that in the UK or US. This means that the unhealthy behaviors related to the Westernized diet have not yet become normalized," she said.

She also highlighted social and cultural reasons: "When we teach people about the health benefits of a different diet then they are more likely to change in China. In the UK, trying to educate away from an unhealthy Western diet is more difficult because it is so normal now."

Li noted uptake of the Chirpy Dragon program was excellent possibly because it was strongly supported by the government and, "in China, students really respect their teachers, so engagement and uptake are really good. These are the reasons why we believe the outcome was so impressive."

Regarding generalization of the Chinese program to other urban areas and countries, initially, the program is most generalizable to countries that share a similar culture Li said.

"Moving forward, our plans are to focus on the transferability of the intervention, initially to other parts of China, and later to Singapore and Malaysia," said Li.  

PLoS Medicine. Published online November 26, 2019. Full text

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