The effect of a multi-component school-based social network intervention on children’s body mass index: a four-arm intervention study

Figures & data

Table 1. Baseline characteristics of participants in total and by intervention condition.

	Total	Water consumption	Physical activity	Multi-component	Control
Variable	(N = 201)	(N = 44)	(N = 54)	(N = 51)	(N = 52)	Test statistic	p
Age (y)	8.51 (0.93)	8.73 (0.66)	8.15 (0.86)	8.84 (1.07)	8.38 (0.93)	F(3,197) = 6.469	<.001
Sex, n (%)						χ^2(3) = 3.418	.332
Boys	93 (46.3)	21 (47.8)	20 (37.0)	28 (54.9)	24 (46.2)
Girls	108 (53.7)	23 (52.2)	34 (63.0)	23 (45.1)	28 (53.8)
Ethnicity, n (%)						χ^2(3) = 20.662	<.001
Dutch	161 (80.1)	36 (81.8)	34 (63.0)	40 (78.4)	51 (98.1)
Non-Dutch	40 (19.9)	8 (18.2)	20 (37.0)	11 (21.6)	1 (1.9)
Weight category, n (%)
Healthy weight	149 (76.0)	37 (88.1)	34 (64.2)	36 (72.0)	42 (82.4)	χ^2(6) = 11.229	.082
Overweight	29 (14.8)	4 (9.5)	10 (18.9)	8 (16.0)	7 (13.7)
Obesity	18 (9.2)	1 (2.4)	9 (17.0)	6 (12.0)	2 (3.9)
zBMI	0.50 (0.98)	0.15 (0.83)	0.73 (1.08)	0.58 (1.04)	0.46 (0.85)	F(3,192) = 2.968	.033
Water consumption	2.38 (1.45)	2.05 (1.09)	2.69 (1.65)	2.48 (1.54)	2.27 (1.39)	F(3,192) = 1.731	.162
SSB consumption	1.28 (0.81)	1.01 (0.81)	1.19 (0.78)	1.27 (0.85)	1.61 (0.72)	F(3,193) = 4.857	.003
Cardiorespiratory physical fitness	4.86 (1.95)	4.90 (2.07)	4.13 (1.81)	5.26 (1.94)	5.09 (1.84)	F(3,180) = 3.110	.028

Notes: zBMI, body mass index z-scores; SSB,Sugar sweetened beverage. Means and standard deviations are presented, unless stated otherwise.

Table 2. Primary and Secondary Outcomes Across Time by Intervention Condition.

	T1	T2	T3
Outcome	M (SD)	M (SD)	M (SD)
Primary outcome
zBMI
Water consumption	0.15 (0.83)	–	0.11 (0.90)
Physical activity	0.73 (1.08)	–	0.64 (1.02)
Multi-component	0.58 (1.04)	–	0.41 (1.06)
Control	0.46 (0.85)	–	0.41 (0.89)
Secondary outcomes
Water Consumption
Water consumption	2.05 (1.09)	2.51 (1.25)	2.45 (1.09)
Physical activity	2.69 (1.65)	2.64 (1.63)	2.91 (1.66)
Multi-component	2.48 (1.54)	2.80 (1.58)	2.72 (1.49)
Control	2.27 (1.39)	1.95 (1.29)	2.25 (1.49)
SSB Consumption
Water consumption	1.01 (0.81)	0.93 (0.86)	0.94 (0.78)
Physical activity	1.19 (0.78)	1.31 (0.78)	1.11 (0.98)
Multi-component	1.27 (0.85)	1.19 (0.90)	1.27 (0.84)
Control	1.61 (0.72)	1.15 (0.72)	1.26 (0.63)
Cardiorespiratory physical fitness
Water consumption	4.90 (2.07)	–	5.45 (2.13)
Physical activity	4.13 (1.81)	–	4.94 (2.07)
Multi-component	5.26 (1.94)	–	5.73 (2.50)
Control	5.09 (1.84)	–	5.35 (2.32)

Notes: zBMI,Body mass index z-scores; SSB, sugar-sweetened beverage. M (SD) are based on the raw data.

Table 3. Mixed-Effects Model for zBMI from Baseline (T1) to Post-Intervention (T3) (N = 201).

	zBMI
Fixed effects	χ^2	df	p
Age	0.238	1	.643
Sex	3.221	1	.086
Ethnicity	0.279	1	.602
Condition	8.720	3	.039
Time	27.794	1	<.001
Condition × Time	24.786	3	<.001

Note. zBMI = Body mass index z-scores. Analyses are based on 394 observations.

Table 4. Mixed-Effects Models for the Secondary Outcome Measures from Baseline (T1) to Mid-Intervention (T2) and Post-Intervention (T3).

	Water consumption						SSB consumption						Cardiorespiratory physical fitness
	T1 to T2^a			T1 to T3^b			T1 to T2^c			T1 to T3^d			T1 to T3^e
Fixed effects	χ^2	df	p	χ^2	df	p	χ^2	df	p	χ^2	df	p	χ^2	df	p
Age	0.526	1	.481	0.008	1	.940	2.292	1	.133	0.715	1	.403	3.792	1	.061
Sex	0.128	1	.713	0.212	1	.620	7.930	1	.010	7.031	1	.010	7.659	1	.013
Ethnicity	0.585	1	.450	3.786	1	.068	7.159	1	.015	5.308	1	.021	0.062	1	.802
Condition	5.736	3	.150	3.814	3	.304	9.579	3	.026	13.131	3	.008	2.066	3	.569
Time	0.835	1	.372	4.498	1	.035	4.946	1	.032	5.424	1	.021	22.815	1	<.001
Condition × Time	9.811	3	.027	2.649	3	.464	16.135	3	.002	5.935	3	.118	2.192	3	.529

Note: SSB, Sugar sweetened beverage.

^aAnalysis are based on 201 participants and 392 observations; ^b Analysis are based on 201 participants and 395 observations; ^c Analysis are based on 201 participants and 393 observations; ^d Analysis are based on 201 participants and 396 observations; ^e Analysis are based on 199 participants and 374 observations.