Overview of primary and secondary outcome(s) and measurement instrument
| Category | Outcome of interest | Measurement instrument | Procedure and instrument properties |
| Anthropometry | BMI-z score, overweight and obesity prevalence54 | Height Portable stadiometer (Charder HM-200P Portstad, Charder Electronic, Taichung City, Taiwan) Weight Digital weight scales (A&D Precision Scale UC-321; A7D Medical, San Jose, CA) | Year 2, Year 4 and Year 6: students invited to have their height and weight measured by trained staff, while wearing light clothing and without shoes. Two measurements each of height and weight taken and measured to the nearest 0.1 cm or 0.1 km. Where measurement differed by 0.5 cm for height and 0.1 kg for weight, a third measure is taken. The mean of all measurements was used. |
| Demographic characteristics | Age (date-of-birth), gender, country of birth, Aboriginal and/or Torres Strait Islander background, language spoken at home, socioeconomic position (postcode) | Health-Behaviours Questionnaire | All participating year 4 and year 6 students; behavioural questionnaire administered by trained staff on electronic tablets (Samsung Galaxy 4) Students encouraged but not required to answer all questions. Estimate questionnaire takes approximately 25–35 min to complete in class time. Students assisted in comprehension of the questions and standard prompts were given to clarify items such as serving sizes for fruit and vegetable consumption. |
| Physical Activity, Sedentary Behaviour and Sleep | Self-report Adherence to Australia’s 24-Hour Movement Guidelines for children (5–17 years)55 Proportion taking active transport to and/or from school | Two questionnaire items examining duration spent in MVPA and screen-time from the Core Indicators and Measures of Youth Health survey on each of the last 7 days.56 One further question examining usual active transportation to and/or from school. A bespoke sleep question item based on Berentzen et al57 in which students report the time they usually went to bed and woke up on school days. | Year 4 and year 6 students invited to complete the self-report behavioural questionnaire on an electronic tablet. We examined the test–retest reliability and criterion validity of the Core Indicators and Measures of Youth Health survey56 and the bespoke sleep item based on Berentzen et al57 among a sample of 26 grade 4 and grade 6 (11.2±1.1 years) primary school children in Victoria, Australia in July–September 2014. Seven-day test–retest reliability was moderate for proportion meeting the physical activity component of the 24-hour movement guidelines (≥60 mins of MVPA/day) on all 7 days (percent agreement 88.5%; kappa 0.61) and fair for ≥5 days/week (percent agreement 73.1%; kappa 0.39). Test–retest reliability for adherence to the screen-time component of the 24-hour movement guideline (≤2 hrs/day for recreation) was moderate (percent agreement 69.2%; kappa 0.41) for all 7 days and fair (percent agreement 61.5%; kappa 0.23) for ≥5 days/wk. Test–retest reliability for duration spent sleeping ≥10 hours/night on school nights was substantial (per cent agreement 84.6%; kappa 0.68). Criterion validity for self-report adherence to the MVPA component of the 24-hour movement guideline against accelerometry measured duration among 19 participants was slight (percent agreement 63.2%; kappa 0.24) for all 7 days. These findings also highlighted children typically under-reported MVPA. |
| Objectively measured Minutes per day spent in sleep, sedentary light, MVPA behaviour | wGT3X-BT ActiGraph wrist worn Accelerometer (ActiGraph, Pensacola, Florida, USA). Students instructed to wear the device for 7 days. | A subsample of year 4 and year 6 students invited to wear an accelerometer (eg, first class of year 6 and year 4 students) at each school. Participants instructed to wear the accelerometer on their non-dominant wrist for 7 days and only take the monitor off for water based and sparing activities and for contact sports (eg, martial arts, Australian Rules Football) as required. | |
| Diet Quality |
| Sixteen question items examined diet quality and were derived from the Child Nutrition Questionnaire (CNQ), the Food, Health, and Choices (FHC-Q)59 and the Simple Dietary Questionnaire (SDQ) questionnaire.60 Two modified question items examining fruit and vegetables serves each day were derived from the CNQ. Fourteen items from the FHC-Q were used to examine non-core food (eg, chips, lollies, chocolate, cakes, biscuits, pastries etc), SSB (eg, sodas, fruit juice/drink/cordial and flavoured milk) and takeaway consumption. One question item from the SDQ examined water consumption. | The CNQ61 used to examine fruit and vegetable consumption and has psychometrically tested among 141 Australian children aged 10–12 years against a 7-day food diary. The reliability intraclass correlation coefficient (ICC) of fruit (ICC=0.66) and vegetables (ICC=0.66) was moderate, and validity for fruit (r=0.48) was moderate and weak for vegetables (r=0.36). FHC-Q used to examine non-core, SSB and water consumption. This questionnaire was psychometrically tested among 221 children aged 9–12 years in New York, USA. The 14-day test-retest reliability of SSB (ICC=0.81), non-core foods (ICC=0.75), takeaway (ICC=0.75) was good to excellent. Validity against another questionnaire (relative validity) was moderate to strong for SSB (r=0.55), non-core foods (r=0.61) and takeaway (r=0.61) foods. The SDQ examined reliability and validity properties (unpublished) among a sample of adolescents aged 13–18 years in Australia. Test–retest reliability for water was high (ICC=0.82) and validity against 24-hour diet recall was very weak (r=−0.436). |
| Well-being | Global summary score and subcomponents including psychological physical health summary score | The 23-item Paediatric Quality of Life Inventory 4.0 (PedsQL)62 questionnaire was used to examine perceived health-related quality of life among participants. PedsQL62 | The PedsQL examines self-rated physical, emotional, school and social health and has been widely used both in Australia63–66 and internationally. It has undergone rigorous psychometric evaluation in a variety of languages67 and has shown high internal consistency (α=0.90–0.91) among children aged 8–11 years in the USA with validity established in comparison with children with chronic health conditions (effect size d=0.63–0.72).62 |
BMI, body mass index; MVPA, moderate-to-vigorous physical activity.