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Cluster-randomised controlled trial to assess the effectiveness and cost-effectiveness of an obesity prevention programme for Chinese primary school-aged children: the CHIRPY DRAGON study protocol
  1. Bai Li1,
  2. Wei Jia Liu2,
  3. Peymane Adab1,
  4. Miranda Pallan1,
  5. Karla Hemming1,
  6. Emma Frew1,
  7. Rong Lin2,
  8. James Martin1,
  9. Wei Liu2,
  10. Kar Keung Cheng1
  1. 1Institute of Applied Health Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
  2. 2Faculty of School Health, Guangzhou Centre for Disease Control and Prevention, Guangzhou, PR China
  1. Correspondence to Professor Peymane Adab; p.adab{at}


Introduction Childhood obesity in China has increased more rapidly and over a shorter time period than in other countries. However, there is a paucity of rigorously developed and evaluated prevention interventions. We aim to evaluate the clinical and cost-effectiveness as well as the implementation process of a complex multicomponent intervention developed using the UK Medical Research Council (MRC) framework. This study provides one of the first examples of rigorous development and evaluation of a childhood obesity prevention programme in a non-western population using the MRC methods.

Methods and analysis A cluster-randomised controlled trial in 40 primary schools in Guangzhou, China, including children aged 6–7 years at baseline. Schools will be randomly allocated to either the usual practice (n=20) or intervention arm (n=20). The 12-month intervention consists of four components targeting diet and physical activity behaviours in and outside school, with family involvement. The primary objective is to compare the difference in mean body mass index (BMI) z-score between the intervention and control arms at the end of the intervention (starting March/April 2017). A sample size of 1640 pupils recruited from 40 schools is sufficient to detect a difference of 0.17 units in the mean BMI z-score with a power of 80% (ICC=0.01. ICC, intraclass correlation coefficient) and a significance level of 5%. Treatment effects will be tested using a mixed linear model in STATA adjusting for the child baseline BMI z-score and clustering by school. All analyses will be by intention to treat. Secondary analyses will additionally adjust for prespecified school-level and child-level covariates. The incremental cost-effectiveness ratio for the intervention versus usual practice will be ‘cost per quality-adjusted life year (QALY)’. Cost per change in BMI z-score will also be assessed. A range of methods will be used to evaluate intervention implementation, mechanisms of impact and contextual factors.

Ethics and dissemination Ethical approval was obtained from the Life and Health Sciences Ethical Review Committee at the University of Birmingham and the Ethical Committee of Guangzhou Centre for Disease Control and Prevention. The primary, secondary, process evaluation and economic evaluation results of the trial will be disseminated through relevant international peer-reviewed journals and conferences.

Trial registration number ISRCTN11867516; Pre-results.

  • childhood obesity prevention
  • process evaluation
  • cost-effectiveness
  • cluster-randomised controlled trial
  • chinese children
  • behavioural change technique

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  • Contributors All authors contributed to the development of the design of the CHIRPY DRAGON Trial. Intervention development was led by BL, with advice from PA and contributions from MP, KKC, KH, EF and WJL. BL, PA, MP, EF and KH form the project management group and advised on the trial design, measurement tools and project overview. KH advised on the sampling, sample size estimation and the statistical analysis plan. JM performed randomisation with support from KH. EF designed the economic evaluation. BL designed process evaluation tools with advice from PA and MP, BL oversees and manages the project fieldwork with WJL being the local supervisor. WJL, RL and WL contribute to the implementation of the project in Guangzhou. Funding for the trial was secured by BL, with support from PA and KKC. BL wrote the first draft of the manuscript. All authors contributed to critical revisions of the paper. The final manuscript was read and approved by all authors.

  • Funding Following external scientific review and approvals from the Chinese authority, the University of Birmingham received a charitable donation from Zhejiang Yong Ning Pharmaceutical Ltd Co. to support its research collaboration with China Guangzhou Centre for Diseases Control and Prevention in obesity prevention among Chinese children. The research is led and hosted by the University of Birmingham.

  • Disclaimer The funder has no role in any aspects of the study’s design, implementation, analyses and reporting.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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