Table 2.

Overview of subgroup effect sizes and heterogeneity for intervention characteristics.

Moderator	Subgroup	k	Hedges’ g	95% CI	Q	p
Intervention type	CBT	15	0.29	0.03–0.55	0.67	.72
	Peer or social support	6	0.45	0.05–0.85
	Counselling	22	0.41	0.20–0.62
CB	No	18	0.49	0.27–0.72	1.83	.18
	Yes	25	0.29	0.09–0.48
MI	No	26	0.31	0.12–0.50	1.19	.28
	Yes	17	0.48	0.24–0.71
Relaxation	No	35	0.42	0.26–0.58	1.69	.19
	Yes	8	0.16	−0.18 to 0.51
Setting	Group	7	0.11	−0.26 to 0.48	2.47	.29
	Individual	32	0.41	0.24–0.59
	Combination	4	0.52	0.02–1.03
Therapy provider	Psychologist/psychiatrist	10	0.39	0.07–0.71	3.37	.64
	Counsellor	4	0.35	−0.15 to 0.84
	Nurse	8	0.62	0.29–0.95
	Peer	7	0.37	0.00–0.73
	Healthcare professional	9	0.24	−0.08 to 0.56
	Other	5	0.21	−0.22 to 0.63
Treatment duration	Short	16	0.40	0.15–0.64	1.13	.57
	Medium	8	0.29	−0.06 to 0.65
	Long	8	0.17	−0.19 to 0.52
	Missing	10

CB: cognitive and/or behavioural techniques; CBT: cognitive behavioural therapy; CI: confidence interval; k: number of studies; MI: motivational interviewing; Q: between-group Q.