Lebares 2021.

Study characteristics
Methods	Study design: randomised controlled trial Study grouping: parallel group
Participants	Baseline Characteristics Enhanced stress resilience training‐1 (ESRT‐1) Age (mean ± SD): 27 ± 2 Sex (N (% female)): 14 (64%) Sample size: 22 Years of experience (mean ± SD): NR Control‐1 (no intervention) Age (mean ± SD): 29 ± 2.8 Sex (N (% female)): 6 (18%) Sample size: 18 Years of experience (mean ± SD): NR Enhanced stress resilience training‐2 (ESRT‐2) Age (mean ± SD): 29 ± 2.4 Sex (N (% female)): 11 (50%) Sample size: 22 Years of experience (mean ± SD): NR Control‐2 (no intervention) Age (mean ± SD): 29 ± 2.2 Sex (N (% female)): 9 (43%) Sample size: 21 Years of experience (mean ± SD): NR Overall Age (mean ± SD): NR Sex (N (% female)): NR Sample size: NR Years of experience (mean ± SD): NR Included criteria: NR Excluded criteria: NR Pretreatment: reported socio‐demographic baseline characteristics of participants randomised to the intervention group were similar to socio‐demographic baseline characteristics of participants randomised to the control group Compliance rate: 89 assigned to intervention 50% actually participated Response rate: NR Type of healthcare worker: post‐graduate residents and surgeons
Interventions	Intervention characteristics Enhanced stress resilience training‐1 (ESRT‐1) Type of the intervention: 2. Intervention type 2 ‐ to focus one’s attention away from the experience of stress Description of the intervention: Focused on the development of mindfulness meditation skills using culturally acceptable language. The number of sessions: 8 Duration of each session on average: 2 hours Duration of the entire intervention: 8 Duration of the entire intervention short vs long: Short Intervention deliverer: MSBR instructor with > 10 years experience Intervention form: NR Control‐1 (no intervention) 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 Enhanced stress resilience training‐2 (ESRT‐2) Type of the intervention: 2. Intervention type 2 ‐ to focus one’s attention away from the experience of stress Description of the intervention: focused on the development of mindfulness meditation skills using culturally acceptable language, explicitly applied to surgery, hospital‐based work, and challenges of maintaining well‐being during demanding training. The number of sessions: 6 Duration of each session on average: 1.5 hours Duration of the entire intervention: 6 Duration of the entire intervention short vs long: Short Intervention deliverer: MSBR instructor with > 10 years experience Intervention form: NR Control‐2 (no intervention) 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	Cohen's Perceived Stress Scale (PSS‐10) Outcome type: ContinuousOutcome Maslach Burnout Inventory ‐ emotional exhaustion Outcome type: ContinuousOutcome Maslach Burnout Inventory ‐ Depersonalisation Outcome type: ContinuousOutcome
Identification	Sponsorship source: NR Country: USA Setting: Hospital Comments: NR Authors name: Carter C. Lebares Institution: Department of Surgery, University of California, San Francisco Email: carter.Lebares@ucsf.edu Address: NR Time period: 2016‐2017
Notes	PSS included in analysis 2.1 and 2.2
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "In 2016 and 2017, we conducted a partially‐blinded, pilot, parallel group randomized trial (NCT#03141190) with 1:1 allocation of PGY‐1 residents to ESRT‐1 (n ¼ 23) versus active Control‐1 (n ¼ 21). ESRT‐1 participants (100% surgical) were" Computer‐generated randomization
Allocation concealment (selection bias)	Unclear risk	One male control mistakenly attended the first week of ESRT‐2 and was allowed to continue in the intervention arm
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Although participants were blinded to assignment and asked not to discuss class content between arms, communication was certainly possible and should be considered in evaluating our results.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Although participants were blinded to the assignment and asked not to discuss class content between arms, communication was certainly possible and should be considered in evaluating our results. Outcomes are self‐report.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Total absences were minimal (10%) across all trials, populations, and conditions; 80% were attributable to scheduled vacations or emergent patient situations. The remainder were attributable to over‐sleeping. Attrition was limited to two female participants (both nonsurgical), who dropped from ESRT‐2 (intervention arm) due to disinterest in performing home practice and feeling ‘‘overloaded’’ by additional obligations.Participants who did not complete the study felt more overloaded however loss to follow‐up is below our pre‐defined cut‐off point.
Selective reporting (reporting bias)	Low risk	Trial registration NCT03141190NCT03518359. No indication of selective reporting.
Other bias	Low risk	No indication of other sources of bias.