Table 1 Primary and secondary outcome measures for the HopSCOTCH trial

Primary Outcome

Body Mass Index (kg/m²)

Portable rigid stadiometer

(model IP0955, Invicta, Leicester, UK); measured

Calibrated digital scale

(model TITHD646, Tanita, Toyko, Japan); measured

Height is measured twice and the average used; if the values differ by >0.5 cm a third measurement is taken and the average of the two closest values used.

Weight, while wearing light clothing, is measured once at baseline, and measured twice at outcome. Average weight used at outcome; if the values differ by ≥0.2 kg a third measure was taken and average of the two closest values used.

BMI is calculated as weight (kg)/(height (m)2). BMI z-score is calculated according to the US Centers for Disease Control (CDC) reference values [28], using the Stata ‘zanthro’ function.

Secondary Outcomes

Waist circumference

Lufkin Executive Steel Tape (W606PM); measured

Average of two waist measurements; if they differ by ≥1 cm, a third measurement is taken and the mean of the two closest used.

Body fat (%)

Tanita Digital Body Composition Monitor (BC-351)[37]; measured

Average of two body percentage fat measurements.

Blood pressure/ heart rate

Welch Allyn ProBP3400; measured

Three blood pressure/heart rate readings are taken at least two minutes apart on the right arm with the child sitting; the average of the two closest readings is used.

Nutrition

4 day food diary; parent report

Parents report child’s consumption of each of 17 food and drink items (0, 1, 2, >2 times) for two weekdays and two weekend days.

Dichotomous (“yes” v “no”) variables are derived for five “healthy behaviours” (high fruit, vegetables, and water; low fatty/sugary foods and non-diet sweet drinks) for each day. The number of healthy behaviours per day are summed to give a score between 0 and 5 (higher score indicating more healthy behaviour).

Physical activity

Actical Accelerometer (Mini Mitter); measured

Worn for 7 full days; ≥5 valid days required. Valid days have ≥10 hours of non-missing data between 6 am-11 pm. Missing data are segments with ≥20 minutes of consecutive “0” counts, or counts >0 that are constant for ≥10 minutes. Outcomes across all valid days: mean activity counts/min, and % time spent in moderate to vigorous physical activity.

Health status

Paediatric quality of life inventory (PedsQL 4.0); self report and parent-proxy versions [38]

Parent-completed 23-item scale that yields total, physical summary, and psychosocial summary scores, each with a possible range of 0–100 (100 = best possible health); quantitative variable.

Body dissatisfaction

Body figure perception questionnaire; self report

[39]

Child picture scale of 1–7 (1 = underweight, 7 = obese) from which child picks perceived and ideal selves. “Perceived” minus “Ideal” self yields a discrepancy index, with positive and negatives scores representing desires to be thinner and fatter, respectively.

Physical appearance and self worth

Modified from Harter’s

perceived competence

scale; self report

Six pairs of statements with binary response format; children choose the statement from each pair that is closest to their competence. Each of the 6 responses is then coded as being either “positive/better perception” or “negative/worse perception”. The 6 responses are analysed as a single outcome.

Behaviour

Strengths and difficulties questionnaire [40]; self report

Parent-completed 25-item scale that yields scores for conduct problems, emotional symptoms, hyperactivity, peer relationships and pro-social behaviour.

Parent Readiness to change

Parent’s readiness to change child’s weight[41]; self report

3 items, each with a possible 5 responses (strongly agree – strongly disagree).

Parent BMI

Weight (kg)/(height (m)2); measured and self report

Baseline values reported for self and partner by responding parent. Values at 12 months measured for the parent(s) present with the child and reported; measured data used preferentially.