School-level variables

School-level variables were collected with an interviewer-administered school questionnaire, which was initially derived from policies, provisions and guidelines on supporting healthy school environment at national-level and district-level. Questions and themes were developed based on previous studies, that is, the PLAY-Ontario study⁽¹⁴⁾, the Environmental Determinants in Young people (SPEEDY) study⁽²⁹⁾ and the Health Behavior in School-aged Children (HBSC) study⁽²⁴⁾. Prior to data collection, we conducted interviews with experts on school health, administrators at local school heath agencies and relevant school staffs to identify the potential key variables according to their experiences regarding obesity prevention strategies. Modifications were also made to the wording and formatting of the questions afterwards.

The final school-level questionnaire involved thirty indicators of five obesity-related themes: (1) School personnel allocation (four indicators): the number, and educational background of school health professionals; position of the responsible person in charge of obesity prevention and control; the management team of obesity prevention. (2) School management policies (seven indicators): written school guidelines; annual work plan; meetings on students’ obesity prevention; availability of students’ health records; monitoring students’ nutrition status; partnership of school sport and health department; participation of class administrators. (3) School health education (nine indicators): health education (e.g. having professional teachers and curriculum schedule), obesity-related lectures, courses and activities for students; obesity-related educational opportunities, feedback of the annual students physical examination, suggestions for overweight/obese students, and school obesity prevention report for parents; obesity-related educational opportunities for teachers. (4) School PA reported by the head of physical education teacher (seven indicators): duration of PA (e.g. compulsory physical education classes and other physical activities) in regular school time; alternative PA in extreme weather conditions; PA homework in holidays; frequency of intramural sports teams and clubs; school sports meeting; promoting overweight/obesity students’ PA involvement; playground equipment like climbing structure and swings, etc. (5) School food environment (three indicators): type of school lunch providers (school canteens or food companies); offering the recipes with food composition to parents; control the overeating of overweight/obese students at school lunch. Each indicator was classified into two categories (Yes or No).

At each school, two trained investigators completed a school-level questionnaire by conducting face-to-face interview with the school health professional, who was responsible for obesity prevention and control. In order to improve the reproducibility of the data, a main investigator took part in data collection of all schools. In order to ensure the reliability and accuracy of the information, plausible answers were asked by investigators to provide more details, or to confirm via relevant school staffs (e.g. school administrators, physical education teachers and health education teachers). Reviewing available documents and field observation were also conducted if required.