Table 2

Type of intervention and study design

	Study ID	Design	No	Intervention
1	Amutio et al (2015)34	RCT	21	Mindfulness
2	Schroeder et al (2016)31	RCT	15	Mindfulness
3	Asuero et al (2014)30	CCT	43	Mindfulness
4	Fortney et al (2013)35	CBA	30	Mindfulness
5	Krasner et al (2009)36	CBA	70	Mindfulness
6	Montero-Marin et al (2017)37	CBA	58	Mindfulness
7	van Wietmarschen et al (2018)38	CBA	54	Mindfulness
8	Cheng et al (2015)23	RCT	34	Gratitude diary
9	West et al (2014)27	RCT	37	Discussion groups
10	McGonagle et al (2020)28	RCT	29	Coaching
11	West et al (2021)29	RCT	64	Discussion groups
12	Gardiner et al (2004)32	CCT	85	Cognitive behavioural training
13	Gardiner et al (2013)33	CCT	69	Cognitive behavioural coaching
14	Holt (2006)24	CCT	106	Email feedback about individual distress levels and a self-help sheet

CBA, control before and after; CCT, controlled clinical trial; RCT, randomised clinical trial.