Mache 2017.

Study characteristics
Methods	Study design: randomised controlled trial Study grouping: parallel group
Participants	Baseline characteristics Psychosocial competency training program Age in years (mean ± SD): 28.1 ± 2.3 Sex (N (% female)): 23 (58%) Sample size: 39 Years of experience (mean ± SD): 1.2 ± 1.4 Control (wait list) Age in years (mean ± SD): 27.6 ± 2.4 Sex (N (% female)): 25 (60%) Sample size: 41 Years of experience (mean ± SD): 1.1 ± 1.3 Overall Age in years (mean ± SD): 28 ± 2.3 Sex (N (% female)): 48 (60%) Sample size: 80 Years of experience (mean ± SD): NR Included criteria: (1) regular access to the Internet, (2) working full time in the hospital, and (3) working experience of max. Two years (4) being able and willing to participate for the next 36 weeks, (5) agreement to complete the questionnaires, (6) no prior knowledge of or experience with a mental health promotion training. Excluded criteria: NR Pretreatment: baseline data on socio‐demographic differences indicated only small, insignificant differences between IG and CG (P > 0.05). Type of healthcare worker: junior physicians working in clinic departments of oncology and haematology medicine Response rate: 66% Compliance rate: 100%
Interventions	Intervention characteristics Psychosocial competency training program Type of the intervention: Intervention type 1 ‐ to focus one’s attention on the experience of stress Description of the intervention: The intervention was based on Lazarus transactional model of stress, including 2 strategies of coping with stressors: problem‐and emotion‐oriented coping. The intervention contained elements of (1) the CBT approach and (2) the solution‐focused approach. Training sessions involved 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 psychotherapists performed all training sessions. Both psychotherapists were registered and accredited as psychotherapists. They had sufficient qualifications and training in cognitive behavioural therapy (CBT), systemic therapy, and solution focused brief therapy. Intervention form: Combination of 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: Oncology and hematology hospital departments 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: NR 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 with the ratio 50%:50% to the 2 study groups (IG or CG). The randomization was performed with a computer‐generated list of numbers."
Allocation concealment (selection bias)	Low risk	Quote: "This list was created by an independent assistant; the other assistant was blinded to the list, securing covered distribution 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	Quote: "There was a total dropout rate (from randomization to analyses) of 10%. Eleven participants decided not to finish the study (reasons included illness and participants did not show up) and did not answer the questionnaires. Overall, 4% (3 of 80) of participants at T1, 6% (5 of 80) of partici‐ pants at T2, and 5% (4 of 80) of participants at T3 did not provide all follow‐up data for the outcomes. Participants who did not provide all follow‐up data did not differ in a meaningful way from those who provided data, neither on the primary outcome or any other baseline outcomes (P > .05)"
Selective reporting (reporting bias)	Unclear risk	No trial registration, nor did we find one online.
Other bias	Low risk	No indication of other bias.