The effect of positive psychology interventions on well-being and distress in clinical samples with psychiatric or somatic disorders: a systematic review and meta-analysis

Table 3 Between-group effects

Outcome measures	N _comp	Hedges’ g	95% CI	Z	Heterogeneity		Fail-safe N
					Q-value	I ²
All studies post-intervention (including outliers)
Well-being	33	0.28	0.07–0.48	2.66**	146.81***	78.20	271
Depression	26	0.27	0.09–0.45	2.97**	66.40***	62.34	132
Anxiety	14	0.47	0.23–0.71	3.78***	36.83***	64.71	135
Stress	6	0.00	-0.62–0.62	0.00	25.35***	80.28	0
All studies post-intervention (excluding outliers)^a
Well-being	29	0.24	0.13–0.35	4.16***	35.13	20.29	137
Depression	21	0.23	0.11–0.34	3.74***	22.26	10.16	66
Anxiety	13	0.36	0.20–0.53	4.24***	16.96	29.26	81
Stress	5	0.27	−0.19–0.73	1.16	11.02	63.69	0
Medium or high quality studies post-intervention
Well-being	14	0.19	0.02–0.37	2.17*	21.99	40.88	17
Depression	12	0.07	-0.19–0.32	0.53	32.43	66.08	0
Anxiety	6	0.22	−0.05–0.49	1.57	8.39	40.39	1
Stress	1	−0.32	− 0.85–0.21	−1.19	0.00	0.00	–
Studies with 8–12 week follow up (including outliers)
Well-being	7	0.41	0.08–0.74	2.46*	19.24**	68.82	28
Depression	5	0.21	0.05–0.37	2.53*	2.55	0.00	4
Anxiety	4	0.35	0.12–0.59	2.91**	4.45	32.54	10
Stress	–	–	–	–	–	–	–

Note. N_comp, number of comparisons, CI confidence interval. *p < 0.05. ** p < 0.01. *** p < 0.001. ^a The effect size for well-being (g = 0.24) corresponds with a standardized mean difference Cohen’s d = 0.24 and unweighted mean r = 0.12; the effect size for depression (g = 0.23) corresponds with d = 0.23 and r = 0.11; the effect size for anxiety (g = 0.36) corresponds with d = 0.37 and r = 0.18; the effect size for stress (g = 0.27) corresponds with d = 0.28 and r = 0.14

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