Table 2.

Summary of characteristics of workplace universal prevention studies included in meta-analysis

Study	Subjects (sample size)	Design	Intervention description	Measure(s)	Follow-up	Results
Ahola et al. (2012) [49]	Employees from private and public sectors (n = 718)	Individual RCT	1. Resource-enhancing group intervention ‘Towards Successful Seniority’ based on career management preparedness. 2. Wait-list control group	BDI	7 months	Significant reduction in the total symptom load of depression in the intervention group compared to the group. The intervention had no statistically significant effect on those with depression symptoms at baseline.
Atlantis et al. (2004) [39]	Casino employees (n = 73)	Individual RCT	1. Combined aerobic and weight training exercise with behavior modification intervention to improve mental health and quality of life outcomes. 2. Wait-list control group	DASS	24 weeks	Depression scales improved significantly for the treatment group relative to the wait-list controls.
				SF-36
Bond and Bunce (2000) [37]	Employees (n = 90) in large media organization	Individual RCT	1. Acceptance and Commitment Therapy (ACT) aiming to enhance an individual’s ability to cope with work-related strain. 2. Innovation Promotion Program (IPP) that helped individuals identify and innovatively change causes of occupation strain. 3. Wait-list control group	GHQ-12	27 weeks	Improvements in mental health and work-related variables were found following both interventions. GHQ scores were significantly lower in the ACT condition than IPP.
				BDI
						BDI score decreased in IPP condition from T1 to T2 and in the ACT condition from T2 to T3.
Kitchener and Jorm (2004) [40]	Employees (n = 301) in two large government departments	Individual RCT	1. Mental Health First Aid training course: to help people in mental health crises and/or in the early stages of mental health problems. 2. Wait-list control group	SF-12	5 months	Significantly greater improvement in mental health (depression and anxiety) for intervention group.
Limm et al. (2011) [11]	Lower and middle level managers in an international manufacturing plant (n = 174)	Individual RCT	1. Stress management intervention: using psychodynamic, conflict and emotion-focused principles and CBT. 2. Wait-list control group	HADS	12 months	Depression improvements were higher in intervention group but did not reach statistical significance.
Mino et al. (2006) [43]	Workers (n = 58) in the Program Development Section within a manufacturing company	Individual RCT	1. Stress management program: based on CBT approach, muscle relaxation training and counselling via email. 2. Control group: No intervention	GHQ-30	3 months	GHQ score decreased in both groups but was not significant. Significant improvement in the depressive symptoms (CES-D) was observed in the stress management group compared to the control group. In the multiple regression analysis, stress management significantly reduced depressive symptoms (CES-D).
				CES-D
Takao et al. (2006) [44]	Supervisors (n = 46) of a Japanese sake brewery and their subordinates (n = 226)	Cluster RCT	1. Supervisor-based education program for employee mental health promotion and active listening training (consulting skills combined with role-playing exercises). 2. Wait-list control group	BJSQ	3 months	Intervention effects were not significant for psychological distress for both male and female subordinates. However, there were significant intervention effects for psychological distress in young male subordinates in white-collar occupations.
Tsutsumi et al. (2009) [48]	Workers (n = 97) in 11 assembly lines in a medium-sized manufacturing company	Cluster RCT	1. Team-based participatory intervention based on active employee involvement, shared work-related goals, and action planning to improve the workplace stress reduction. 2. Control group: No organized activities provided	GHQ	13 months	GHQ scores significantly deteriorated in control lines; scores of intervention lines remained the same.
Vuori et al. (2012) [50]	Workers (n = 718) across 17 participating government and private organizations	Individual RCT	1. One week resource building group intervention: career management and mental health workshop using active learning process, social modelling, gradual exposure and role playing. 2. Control group: literature package with career management related information	BDI	7 months	The program significantly decreased depressive symptoms and intentions to retire early, and increased mental resources among the intervention group compared to the controls.

BDI, Beck Depression Inventory; BJSQ, Brief Job Stress Questionnaire; CBT, cognitive behavioral therapy; CES-D, Center for Epidemiologic Studies for Depression; DASS, Depression, Anxiety, and Stress Scales; GHQ, General Health Questionnaire; HADS, Hospital Anxiety and Depression Scale; SF-12, 12-item Short Form Health Survey; SF-36, 36-item Short Form Health Survey.