Effectiveness of a theory-based back care intervention on spine-related behavior among pupils: a school-based randomised controlled trial (T-Bak study)

Table 3 Means (SD), interaction and main effects of group and time on outcome variables at baseline, immediate, 3 and 6 months’ follow-ups between intervention and control groups in the T-Bak study

Variable (score range)	Score (mean ± SD)								Interaction effect (F): Time×Group	Time (F)	Group (F)
	Baseline		Immediate		3-months follow-up		6-months follow-up
	Intervention (n = 52)	Control (n = 52)	Intervention (n = 51)	Control (n = 49)	Intervention (n = 50)	Control (n = 50)	Intervention (n = 51)	Control (n = 48)
Behavior (6–30)	17.26 ± 4.97	18.30 ± 5.00	26.35 ± 3.61	17.20 ± 5.59	26.68 ± 3.58	18.30 ± 4.84	26.84 ± 2.95	18.08 ± 5.13	29.266*	24.693*	192.985*
P-value	0.36		< 0.001		< 0.001		< 0.001
Knowledge (0–10)	4.16 ± 1.53	4.30 ± 1.46	7.45 ± 1.83	4.16 ± 1.61	7.82 ± 1.8	4.16 ± 1.53	7.80 ± 1.84	4.35 ± 1.65	29.395*	27.278*	235.725*
P-value	0.65		< 0.001		< 0.001		< 0.001
Skills (0–46)	13.26 ± 9.37	13.70 ± 10.18	38.75 ± 10.30	13.53 ± 10.18	38.20 ± 11.83	12.48 ± 9.29	37.73 ± 11.63	12.79 ± 9.68	38.556*	34.229*	330.483*
P-value	0.95		< 0.001		< 0.001		< 0.001
Self-efficacy (4–16)	10.66 ± 2.86	10.2 ± 2.97	14.22 ± 2.17	10.80 ± 2.73	13.68 ± 2.30	9.90 ± 3.11	13.7 ± 1.88	10.44 ± 3.05	9.985*	11.512*	104.833*
P-value	0.66		< 0.001		< 0.001		< 0.001
Beliefs (6–30)	19.16 ± 4.19	18.08 ± 4.83	26.31 ± 4.39	18.18 ± 4.42	26.32 ± 5.09	18.06 ± 5.02	26.84 ± 4.40	18.67 ± 4.62	14.692*	16.879*	190.811*
P-value	0.24		< 0.001		< 0.001		< 0.001

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