# Abstract

 

## BACKGROUND/OBJECTIVES: Obesity prevention during adolescence is a health priority. The 'Physical Activity 4 Everyone' (PA4E1) study tested a multi-component physical activity intervention in 10 secondary schools from socio-economically disadvantaged communities. This paper aimed to report the secondary outcomes of the study; to determine whether the intervention impacted on adiposity outcomes (weight, body mass index (BMI), BMI *z*-score), and whether any effect was moderated by sex, baseline BMI and baseline physical activity level, at 12 and 24 months. 

## SUBJECTS/METHODS: A cluster randomised controlled trial was conducted in New South Wales, Australia. The school-based intervention included seven physical activity strategies targeting the following: curriculum (strategies to maximise physical activity in physical education, student physical activity plans, an enhanced school sport programme); school environment (physical activity during school breaks, modification of school policy); and parents and the community (parent engagement, links with community physical activity providers). Students' weight (kg), BMI and BMI *z*-score, were collected at baseline (Grade 7), 12 and 24 months. Linear Mixed Models were used to assess between-group mean difference from baseline to 12 and 24 months. Exploratory sub-analyses were undertaken according to three moderators of energy balance. 

## RESULTS: A total of 1150 students (mean age=12 years) provided outcome data at baseline, 1051 (91%) at 12 months and 985 (86%) at 24 months. At 12 months, there were group-by-time effects for weight (mean difference=--0.90 kg (95% confidence interval (CI)=--1.50, −0.30), *P*\<0.01) and BMI (−0.28 kg m^−2^ (−0.50, −0.06), *P*=0.01) in favour of the intervention group, but not for BMI *z*-score (−0.05 (−0.11; 0.01), *P*=0.13). These findings were consistent for weight (−0.62 kg (−1.21, 0.03), *P*=0.01) and BMI (−0.28 kg m^−2^ (−0.49, −0.06), *P*=0.01) at 24 months, with group-by-time effects also found for BMI *z*-score (−0.08 (−0.14; −0.02), *P*=0.02) favouring the intervention group. 

## CONCLUSION: The PA4E1 school-based intervention achieved moderate reductions in adiposity among adolescents from socio-economically disadvantaged communities. Multi-component interventions that increase adolescents' engagement in moderate-to-vigorous physical activity (MVPA) may assist in preventing unhealthy weight gain. # Results 

## Sample Of the 22 eligible schools, 13 were approached to participate in the study. Ten schools consented to participate (77%) and parental consent was obtained for 1233 of the 1468 Grade-7 students in the 10 schools (84%). A total of 1150 students provided adiposity outcome data at baseline, 1051 (91%) at mid-point (12 months) and 985 (86%) at 24 months. Demographic characteristics of the sample at baseline, 12 and 24 months are outlined in [Table 1](#). At baseline, the mean age of participants was 12 years, 51% were female, 17% were overweight and 5% were obese, and 64% did not meet the physical activity recommendation of ⩾60 min of MVPA per day. Participants who were lost to follow-up were more likely to be older in age (*P*=0.03) and did not speak English as a primary language (*P*=0.02) compared with those who provided outcome data at all time points. At 24 months, all 5 intervention schools had implemented 6 of the 7 physical activity strategies. The exception was strategy 5 (school policy); 4 of the 5 schools had developed a school policy. All intervention implementation strategies were delivered as planned. The majority of intervention group PE teachers (*n*=35) reported using pedometers to increase activity levels in PE (88.9%), and 58.8% reported including student physical activity plans each term. All schools were represented by at least one PE teacher (range 1--5) at each professional learning workshop. More information on intervention delivery can be found in the 24-month physical activity outcome paper.^[16](#)^ 

## Indicators of adiposity The results for the 12- and 24-month adiposity outcomes are presented in [Table 2](#). At 12 months, there were group-by-time effects for weight (mean difference (95% CI) =−0.90 kg (−1.50; −0.30), *P*\<0.01) and BMI (−0.28 kg m^−2^ (−0.50; −0.06), *P*=0.01) in favour of the intervention group, but not for BMI *z*-score (−0.05 (−0.11; 0.01), *P*=0.13). These findings were consistent for weight (−0.62 kg (−1.21; −0.03), *P*=0.01) and BMI (−0.28 kg m^−2^ (−0.49; −0.06), *P*=0.01) at 24 months, with group-by-time effects also found for BMI *z*-score (−0.08 (−0.14; −0.02), *P*=0.02) favouring the intervention group. Intervention effects were significant for all adiposity outcomes at 12 and 24 months in both the complete cases and multiple imputation analyses ([Supplementary Appendix 1 and 2](#)). 

## Subgroup analyses The results of the subgroup analyses are presented in [Supplementary Appendix 3](#). 

### Sex There was weak evidence of a differential treatment on effect on weight in males compared with females (three-way interaction *P*=0.22). Among males there was a statistically significant treatment effect at 24 months in favour of the intervention group (−1.26 kg (−2.11; −0.41), *P*=0.01). There were no significant effects on weight, BMI and BMI *z*-score at either 12 or 24 months for females. 

### Weight status at baseline We found very little evidence of differential treatment effects depending on baseline weight for weight (*P*=0.50), BMI (*P*=0.57) or BMI *z*-score (*P*=0.64). Nevertheless, we did observe the following results. Among underweight and normal weight participants combined, there were significant effects for weight (−0.71 kg (−1.28; −0.14), *P*=0.04), BMI (−0.33 kg m^−2^ (−0.55; −0.10), *P*=0.01) and BMI *z*-score (−0.08 (−0.15; −0.01), *P*=0.01) in favour of the intervention group at 12-month follow-up. Similar findings for weight (−0.71 kg (−1.28; −0.14), *P*=0.04), BMI (−0.33 kg m^−2^ (−0.55; −0.10), *P*=0.01) and BMI *z*-score (−0.08 (−0.15; −0.01), *P*=0.01) in underweight/normal weight participants were found at 24 months in favour of the intervention group. Among overweight and obese students, no significant effects were found at 12 or 24 months for weight (12 months=−1.29 kg (−3.12; 0.53), *P*=0.16; 24 months=−1.16 kg (−2.98; 0.67), *P*=0.30), BMI (12 months=−0.39 kg m^−2^ (−1.01; 0.22), *P*=0.21; 24 months=−0.18 kg m^−2^ (−0.80; 0.44), *P*=0.45) and BMI *z*-score (12 months=−0.07 (−0.21; 0.07), *P*=0.31; 24 months=−0.00 (−0.14; 0.14), *P*=0.54). 

### Physical activity level at baseline We found no evidence of differential treatment effects depending on activity status at baseline for weight (*P*=0.94), BMI (*P*=0.95) or BMI *z*-score (*P*=0.31).There was no significant effect on weight, BMI or BMI *z*-score for either active or inactive students at 12 or 24 months. ::::table-wrap

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##

##

## Sample characteristics at baseline, 12 and 24 months for students who provided adiposity outcome measures

:::

*Variable* *Subgroup* *Baseline* *Mid-point (12 months)* *Follow-up (24 months)*

______________________________________________________________________

*Control (*n*=505)* *Intervention (*n*=645)* *Control (*n*=459)* *Intervention (*n*=592)* *Control (*n*=425)* *Intervention (*n*=560)*
Sex[a](#) Male 244 (49%) 299 (48%) 219 (48%) 268 (46%) 219 (52%) 266 (48%)
Female 254 (51%) 329 (52%) 233 (52%) 311 (54%) 204 (48%) 287 (52%)
ATSI[b](#) No 456 (91%) 581 (92%) 415 (91%) 540 (92%) 390 (92%) 520 (93%)
Yes 44 (8.8%) 53 (8.4%) 39 (8.6%) 45 (7.7%) 35 (8.2%) 40 (7.1%)
Language[c](#) English 474 (97%) 593 (99%) 425 (97%) 539 (98%) 392 (97%) 506 (98%)
Other 15 (3.1%) 8 (1.3%) 11 (2.5%) 9 (1.6%) 11 (2.7%) 8 (1.6%)
SEIFA[d](#) Low 295 (61%) 349 (59%) 260 (60%) 308 (57%) 236 (59%) 285 (56%)
High 190 (39%) 246 (41%) 172 (40%) 235 (43%) 163 (41%) 222 (44%)
Rurality Metropolitan 236 (47%) 340 (53%) 220 (48%) 324 (55%) 207 (49%) 304 (54%)
Rural 269 (53%) 305 (47%) 239 (52%) 268 (45%) 218 (51%) 256 (46%)
BMI category[e](#) Underweight 30 (6.3%) 41 (7.3%) 19 (5.8%) 29 (6.9%) 7 (2.0%) 12 (2.5%)
Normal weight 321 (67%) 397 (71%) 214 (65%) 291 (69%) 214 (62%) 320 (66%)
Overweight 100 (21%) 97 (17%) 72 (22%) 75 (18%) 95 (28%) 111 (23%)
Obese 29 (6.0%) 27 (4.8%) 25 (7.6%) 24 (5.7%) 27 (7.9%) 45 (9.2%)
MVPA[f](#) Inactive (\<60 min per day) 324 (67%) 414 (67%) 277 (72%) 340 (68%) 226 (72%) 261 (66%)
Active (⩾60 min per day) 162 (33%) 207 (33%) 108 (28%) 158 (32%) 90 (28%) 137 (34%)
Age[g](#) median (min., max.) 12 (11,13) 12 (11,13) 13 (12,14) 13 (12,14) 14 (12,15) 14 (12,15)
Height[h](#) Mean (s.d.) 156.81 (7.92) 157.13 (7.47) 162.56 (8.20) 162.39 (8.73) 167.28 (9.40) 167.02 (7.88)
Weight[i](#) Mean (s.d.) 50.01 (12.05) 49.43 (11.05) 55.96 (12.60) 55.22 (12.51) 61.50 (13.23) 60.52 (12.72)
BMI[j](#) Mean (s.d.) 20.19 (3.81) 19.90 (3.59) 21.04 (3.76) 20.77 (3.96) 21.90 (4.33) 21.64 (4.06)
BMI *z*-score[k](#) Mean (s.d.) 0.58 (1.16) 0.54 (1.11) 0.61 (1.13) 0.55 (1.11) 0.72 (1.09) 0.65 (1.12)

Abbreviations: ATSI, Aboriginal and Torres Strait Islander; BMI, body
mass index; MVPA, moderate-to-vigorous physical activity; SEIFA,
Socio-Economic Indexes for Australia.

Baseline (control=7, intervention=17), mid-point (control=7,
control=13), follow-up (control=2, intervention=7).

Baseline (control=5, intervention=11), mid-point (control=5, control=7),
follow-up (control=0, intervention=0).

Baseline (control=16, intervention=44), mid-point (control=23,
control=44), follow-up (control=22, intervention=46).

Baseline (control=20, intervention=50), mid-point (control=27,
control=49), follow-up (control=26, intervention=53).

Baseline (control=25, intervention=83), mid-point (control=129,
control=173), follow-up (control=82, intervention=72).

Baseline (control=19, intervention=24), mid-point (control=74,
control=94), follow-up (control=109, intervention=162). Participants
(*n*).

Baseline (control=491, intervention=593), mid-point (control=409,
control=516), follow-up (control=407, intervention=534).

Baseline (control=491, intervention=590), mid-point (control=442,
control=573), follow-up (control=415, intervention=549).

Baseline (control=491, intervention=587), mid-point (control=440,
control=562), follow-up (control=410, intervention=547).

Baseline (control=491, intervention=584), mid-point (control=440,
control=562), follow-up (control=409, intervention=547).

Baseline (control=484, intervention=571), mid-point (control=406,
control=502), follow-up (control=343, intervention=488).:::: ::::table-wrap
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##

##

## Changes in adiposity outcomes from baseline to 12- and 24-month follow-up

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*Outcome* *Intervention* *Control* *Intervention--Control*

______________________________________________________________________

*Difference in change between groups*\
*Baseline (*n*=645) mean (95% CI)* *12 m (*n*=592) mean (95% CI)* *24 m (*n*=560) mean (95% CI)* *P-value (baseline to follow-up)* *Baseline (*n*=505) mean (95% CI)* *12 m (*n*=459) mean (95% CI)* *24 m (*n*=425) mean (95% CI)* *P-value (baseline to follow-up)* *Baseline to 12 m* *P-value* *Baseline to 24 m* *P-value* *Group × time P-value*
Weight (kg) 50.08 (48.83, 51.34) 55.91 (54.65, 57.17) 61.08 (59.83, 62.34) \<0.0001 50.04 (48.69, 51.38) 56.48 (55.13, 57.83) 61.94 (60.59, 63.30) \<0.001 −0.90 (−1.50, −0.30) **0.0034** −0.62 (−1.21, −0.03) **0.0396** **0.0106**
BMI (kg m^−2^) 20.27 (19.76, 20.78) 21.07 (20.56, 21.59) 21.86 (21.34, 22.37) \<0.0001 20.19 (19.65, 20.72) 21.27 (20.73, 21.81) 22.06 (21.52, 22.60) \<0.001 −0.28 (−0.50, −0.06) **0.0126** −0.28 (−0.49, −0.06) **0.0116** **0.0145**
BMI *z*-score 0.62 (0.47, 0.77) 0.61 (0.46, 0.75) 0.69 (0.54, 0.84) 0.0002 0.59 (0.43, 0.74) 0.66 (0.50, 0.81) 0.71 (0.55, 0.86) \<0.0001 −0.05 (−0.11, 0.01) **0.1307** −0.08 (−0.14, −0.02) **0.0062** **0.0226**

Abbreviations: BMI, body mass index; CI, confidence interval. Bold
values are statistically significant.::::


Extracted trial result:
Outcome: BMI z-score at 12months (continuous)
Intervention: Multi-component physical activity
Comparator: Usual PE and sport programmes
Intervention group size: 592
Intervention mean: 0.61
Intervention standard deviation: 1.8
Comparator group size: 459
Comparator mean: 0.66
Comparator standard deviation: 1.69
Notes: Back calculated the SD values from CI