Table 2.

Main results from mixed models.

Participant questionnaires		Linear contrasta			Group-by-time interactionb
		Estimatea	95% CI	P value	F statistic	DFc	P value
GHSQd (intention to treat)
	Formal resources	0.39	–0.34 to 1.12	.30	0.85	2/877	.43
	Informal resources	0.36	–1.21 to 1.92	.65	0.70	2/811	.50
GHSQ (per-protocol) – formal resources		0.18	–0.62 to 0.98	.66	0.14	2/757	.87
GHSQ (dropout)b – formal resources		1.35	–0.51 to 3.21	.15	1.18	2/145	.31
GHSQ (controlled for site)e – formal resources		0.39	0.34 to 1.13	.29	0.85	2/877	.43
ATSPPHf		–0.15	–0.91 to 0.61	.70	1.39	2/850	.25
SSOSHg		0.08	–1.13 to 1.28	.90	0.03	2/876	.97
YES-MHh: self		–0.09	–0.73 to 0.55	.79	0.12	2/801	.89
YES-MH: service		0.47	–0.40 to 1.34	.29	0.60	2/823	.55
YES-MH: system		0.62	–0.26 to 1.50	.17	1.31	2/818	.27
YES-MH: total		0.16	–1.52 to 1.83	.85	0.08	2/738	.92

^aThe linear contrast tests the change from baseline to end of the trial across groups (primary outcome); (6 months – baseline) in control minus intervention. Positive values indicate larger increases in the intervention group.

^bThe group-by-time interaction tests for any difference in the group trajectories (not primary outcome). Sensitivity analysis controls for all variables at α= .20. These variables are listed in Multimedia Appendix 7.

^cDF: degree of freedom.

^dGHSQ: General Help-Seeking Questionnaire.

^eAn additional sensitivity analysis controlling for site as fixed effects was conducted, but site was not significant and results were similar to those for the main model.

^fATSPPH: Attitudes Toward Seeking Professional Psychological Help Scale.

^gSSOSH: Self-Stigma of Seeking Help Scale.

^hYES-MH: Youth Efficacy/Empowerment Scale–Mental Health.