Comparison 2. Web‐based cognitive‐behavioural treatment (CBT) versus waiting‐list control.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Drug use: amphetamine‐type stimulant use	1	160	Std. Mean Difference (Random, 95% CI)	‐0.1 [‐0.54, 0.34]
2 Drug use	1	160	Std. Mean Difference (Random, 95% CI)	‐0.05 [‐0.49, 0.39]
3 Psychological variables: intended help‐seek	1	160	Std. Mean Difference (Fixed, 95% CI)	0.31 [‐0.13, 0.75]
4 Psychological variables: K‐10 score	1	160	Std. Mean Difference (Fixed, 95% CI)	‐0.1 [‐0.54, 0.34]
5 Psychological variables: days out of role	1	160	Std. Mean Difference (Random, 95% CI)	0.02 [‐0.42, 0.46]
6 Psychological variables: days part out of role	1	160	Std. Mean Difference (Random, 95% CI)	‐0.05 [‐0.49, 0.39]
7 Psychological variables: quality of life	1	160	Std. Mean Difference (Random, 95% CI)	‐0.19 [‐0.63, 0.25]