Errazuriz 2022.

Study characteristics
Methods	Study design: randomised controlled trial Study grouping: parallel group
Participants	Baseline characteristics Mindfulness‐based stress reduction (MSBR) Age (mean ± SD): 40.9 ± 12 Sex (N (% female)): 34 (97%) Sample size: 35 Years of experience (mean ± SD): 16.8 ± 11 Psychoeducational stress management (SMC) Age (mean ± SD): 40.1 ± 14 Sex (N (% female)): 33 (97%) Sample size: 34 Years of experience (mean ± SD): nr ± (11) Wait list Age (mean ± SD): 39.6 ± 11 Sex (N (% female)): 36 (100%) Sample size: 36 Years of experience (mean ± SD): 14 ± 10 Overall Age (mean ± SD): NR Sex (N (% female)): NR Sample size: NR Years of experience (mean ± SD): NR Included criteria: (i) non‐physician healthcare workers; (ii) aged ≥ 18 years; (iii) with a permanent work contract; and (iv) in direct contact with patients. Excluded criteria: participants were excluded if they reported suicidal ideation or problematic alcohol consumption at enrolment as measured in items 8 and 11 of the 45‐item Outcome Questionnaire Pretreatment: the three groups did not differ significantly in any of the collected baseline characteristics, except for levels of ’rewards’ at work and scores in the mindfulness ‘describing’ facet Compliance rate: NR Response rate: NR Type of healthcare worker: various healthcare workers
Interventions	Intervention characteristics Mindfulness‐based stress reduction (MSBR) Type of the intervention: Intervention type 2 ‐ to focus one’s attention away from the experience of stress Description of the intervention: Mindfulness‐based stress reduction (MBSR) courses teach individuals to observe thoughts, emotions, and situations non‐judgementally and non‐reactively via exercises, including meditation The number of sessions: 8 Duration of each session on average: 2 hours Duration of the entire intervention: 8 weeks Duration of the entire intervention short vs long: short Intervention deliverer: Clinical psychologist Intervention form: Group Psychoeducational stress management (SMC) Type of the intervention: Intervention type 1 ‐ to focus one’s attention on the experience of stress Description of the intervention: The training was aimed to develop efficient coping strategies through lectures addressing work‐related stress and wellbeing, interpersonal support, and experiential activities. The number of sessions: 8 Duration of each session on average: 2 hours Duration of the entire intervention: 8 weeks Duration of the entire intervention short vs long: short Intervention deliverer: Clinical psychologist Intervention form: Group 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	General Health Questionnaire (GHQ‐12) Outcome type: ContinuousOutcome 45‐item Outcome Questionnaire (OQ‐45) Outcome type: ContinuousOutcome Perceived Stress Scale (PSS) Outcome type: ContinuousOutcome
Identification	Sponsorship source: NR Country: Chile Setting: Mixed healthcare settings including: a tertiary hospital, a teaching hospital and an outpatient complex. Comments: NR Authors name: Antonia Errazuriz Institution: Department of Psychiatry, School of Medicine, Pontificia Universidad Catolica de Chile Email: anerrazuriz@uc.cl Address: School of Medicine, Pontificia Universidad Catolica de Chile, Diagonal Paraguay 362, Santiago, 8330077, Chile Time period: NR
Notes	We kindly received the mean and SD of the primary outcome from author A. Errazuriz.  PSS included in analysis 1.1 and 1.2 and 2.1 and 2.2 and 5.1 and 5.2 and 6.1 and 6.2
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Participants were randomized into three groups (1:1:1 ratio) using computer‐generated random numbers, stratified by work position."
Allocation concealment (selection bias)	Unclear risk	Quote: "Allocation was executed by ordering subjects according to the random number within strata and assigning the subjects within each stratum to groups 1, 2, and 3, consecutively, until exhausting the number of subjects within each stratum." Insufficient information to understand whether intervention allocations could have been foreseen in advance of, during, enrolment.
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	High risk	52 of the 105 (50%) randomised participants were included in the analysis. Reasons not provided. Not reported whether lost to follow‐up at random.
Selective reporting (reporting bias)	High risk	Trial registration: ISRCTN12039804. Did not report on Maslach Burnout Inventory and  number of sick leaves in the previous three months
Other bias	Unclear risk	Compliance rate and response rate not reported.