Mache 2018.

Study characteristics
Methods	Study design: randomised controlled trial Study grouping: parallel group
Participants	Baseline characteristics Mental health promotion program Age in years (mean ± SD): 27.3 ± 2.5 Sex (N (% female)): 22 (62%) Sample size: 35 Years of experience (mean ± SD): 1.4 ± 1.1 Control (wait list) Age in years (mean ± SD): 27.1 ± 2.1 Sex (N (% female)): 24 (68%) Sample size: 35 Years of experience (mean ± SD): 1.1 ± 1.2 Overall Age in years (mean ± SD): 27 ± 2.4 Sex (N (% female)): 46 (66%) Sample size: 70 Years of experience (mean ± SD): 1 ± 1.3 Included criteria: inclusion criteria were as follows: (a) employment in emergency medicine, (b) working full‐time in the hospital, (c) working experience of less than 3 years, (d) being able and willing to participate, (e) agreement to complete the questionnaires, and (f) e‐mail access, availability of a computer, tablet, or a smartphone, and access to the Internet. Excluded criteria: exclusion criteria were as follows: (a) having any psychiatric illness, (b) taking any psychiatric drugs, (c) engaging any counselling service, and (d) parallel use of psychosocial counselling. Pretreatment: baseline data on socio‐demographic differences indicated only small, insignificant differences between the intervention and the comparison group. Type of healthcare worker: exclusively junior physicians Response rate: NR Compliance rate: 100%
Interventions	Intervention characteristics Mental health promotion program Type of the intervention: Intervention type 1 ‐ to focus one’s attention on the experience of stress Description of the intervention: The main focus was on actual working situations and problems, coping strategies, and support between colleagues and goals for the future. The training sessions included psycho‐education (theoretical input, watching videos, oral group discussions, experiential exercises, and home assignments). The number of sessions: 12 Duration of each session on average: 1.5 hours Duration of the entire intervention: 12 weeks Duration of the entire intervention short vs long: long Intervention deliverer: Two qualified psychologists, both trained in cognitive behavioural and solution‐focused work, performed the training. Intervention form: Group and individual, face‐to‐face and at home Control (wait list) Type of the intervention: NA Description of the intervention: NA The number of sessions: NA Duration of each session on average NA Duration of the entire intervention: NA Duration of the entire intervention short vs long: NA Intervention deliverer: NA Intervention form: NA
Outcomes	Perceived Stress Questionnaire (PSQ) Outcome type: ContinuousOutcome Maslach Burnout Inventory ‐ Emotional Exhaustion Outcome type: ContinuousOutcome
Identification	Sponsorship source: NR Country: Germany Setting: Six hospitals: clinic departments of emergency medicine Comments: NR Authors name: Stefanie Mache Institution: Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg‐Eppendorf Email: s.mache@uke.de Address: Seewartenstrasse 10, 20459 Hamburg, Germany Time period: NR
Notes	MBi‐EE included in analysis 1.1, 1.2
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "participants were randomized at a ratio of 1: 1 to the two study arms (intervention or control group). The randomization was performed with a computer‐generated list of numbers."
Allocation concealment (selection bias)	Low risk	Quote: "This list was generated by an independent research assistant; the other researcher was blinded to the list, ensuring concealed allocation to research conditions."
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants were not blinded.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Participants were not blinded whereas outcomes are self‐reported.
Incomplete outcome data (attrition bias) All outcomes	Low risk	63 of the 70 randomised participants included in the analysis.
Selective reporting (reporting bias)	Unclear risk	No trial registration, nor did we find on online
Other bias	Unclear risk	Response rate not reported.