Erogul 2014.

Study characteristics
Methods	Study design: RCT Study grouping: parallel group Unit of randomisation: individuals Power (power sample size calculation, level of power achieved): A sample size calculation determined that 26 participants per group would be required to detect a difference with an effect size of 0.8, with a power of 80% at significance level of 0.05; in part no significant results, according to publication may be due to study being underpowered Imputation of missing data: no imputation of missing data; per‐protocol analysis (only participants who took part in allocated intervention)
Participants	Country: USA Setting: SUNY Downstate School of Medicine in Brooklyn Age: mean = 23.5 (SD = 1.7) years Sample size (randomised): 59 (not specified; according to authors at baseline) Sex: 26 women, 33 men Comorbidity (mean (SD) of respective measures in indicated, if available) at baseline: both control and treatment groups statistically comparable to the norm for resilience, perceived stress and self‐compassion Population description: first‐year class of medical students Method of recruitment: recruited from 2010 ‐ 2011 first‐year class of medical students at SUNY Downstate School of Medicine in Brooklyn, New York Inclusion criteria: not specified Exclusion criteria: not specified Attrition (withdrawals and exclusions): after replacement of 22 participants (IG: 10, CG: 10) who refused to participate in allocated intervention: 2 dropouts (IG: 1/29 (3.4%); CG: 1/30 (3.3%); information about 1 dropout in CG received from authors) Reasons for missing data: 1 dropout from IG: scholastic reasons; for other withdrawals unclear; reasons for refusal of 22 randomised participants not specified
Interventions	Intervention: abridged MBSR (initially randomised: 39; after refusal of 10 randomised participants to take part in allocated group: n = 29) delivery: face‐to‐face; group sessions; weekly handouts, homework reflections providers: licensed psychotherapist with 35 years of regular practice in mindfulness meditation who has undergone the MBSR foundational programme at the University of Massachusetts Center for Mindfulness duration of treatment period and timing: 8 weekly 75‐minute sessions and programme of suggested meditation at home (20 minutes daily practice); full‐day retreat offsite between 7th and 8th weekly meeting description (content, components): IN‐CLASS SESSIONS: 1) teach the experiential practices of mindfulness‐based meditation, body scan, and breathing‐based yoga and 2) to provide a cognitive curriculum about understanding stress and how best to manage reactivity HOMEWORK: individual sessions of daily meditation for 20 minutes; meditations started with narrated guidance (body scan, breath meditation, gentle yoga); each 20‐minute track = abbreviated version of weekly 60‐minute experience in mindfulness meditation and corresponds to theme of the weekly meeting; after week 4: shift from guided to self‐meditation RETREAT: to immerse the participants in a full day of mindfulness, thus leveraging the experience they had gained so far in the programme to deepen their mindfulness practice compliance: 100% attendance of participants at full‐day retreat integrity of delivery: not specified economic information: not specified theoretical basis: MBSR Control: no intervention (initially randomised: 42; after refusal of 12 randomised participants to take part in allocated group: n = 30)
Outcomes	Outcomes collected and reported: perceived stress ‐ PSS‐10 self‐compassion ‐ SCS resilience ‐ RS Time points measured and reported: 1) pre‐intervention; 2) post‐intervention (at conclusion of intervention); 3) 6‐month follow‐up (6 months post‐intervention) Adverse events: not specified
Notes	Contact with authors: We contacted authors for the number of participants randomised in total and to each group (refusals from participants after randomisation) as well as the number of participants analysed at each time point (Erogul 2018 [pers comm]) Study start/end date: study carried out in March of the first year of medical school; exact study dates not specified Funding source: grant from the Arnold P Gold Foundation Declaration of interest: The authors report no conflict of interest Ethical approval needed/obtained for study: approved by the SUNYDownstate IRB Comments by authors: checklist of Items for Reporting Trials of Nonpharmacologic Treatments in appendix Miscellaneous outcomes by the review authors: information received from authors: "We had: 30 controls 29 treatment at the start of the study. By the end, because of attrition of one individual from each arm we had 29 controls, 28 study subjects = 57 participants total analyzed" Correspondence: Mert Erogul; Department of Emergency Medicine, SUNY Downstate School of Medicine, 155 Lafayette Ave #1a, Brooklyn, NY 11238; erogul1@gmail.com
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "The selection process involved using a random number generator to select students who had been numbered according to their alphabetical order in the class." Quote: "After this random allocation, students were asked by email to consent to participate in the group to which they had been assigned. A proportion of students declined to participate (as indicated below), and were replaced by other students selected at random in a similar fashion from the remaining members of the class on a rolling basis until a complement of 30 control and 29 study participants was achieved." Quote: "There were no significant differences with respect to age, sex, PSS, SCS and RS scores at baseline." Judgement comment: The investigators describe a random component in the sequence‐generation process (random‐number generator). However, after 22 participants refused to participate in allocated intervention after randomisation, they were replaced by other students selected at random from class "in a similar fashion". It is not clear how the second random selection was performed; verified baseline comparability of groups for sociodemographic characteristics (age, gender) and outcomes of interest on the basis of analysis
Allocation concealment (selection bias)	Unclear risk	Quote: "This process blindly allocated thirty students to control and thirty to intervention." Quote: "After this random allocation, students were asked by email to consent to participate in the group to which they had been assigned. A proportion of students declined to participate (as indicated below), and were replaced by other students selected at random in a similar fashion from the remaining members of the class on a rolling basis until a complement of 30 control and 29 study participants was achieved." Judgement comment: participants and investigators enrolling participants could probably not foresee assignment during computer‐based allocation (exact method not described); but insufficient information about allocation concealment for allocation of participants who replaced the ones who refused to participate in allocated group
Blinding of participants and personnel (performance bias) Subjective outcomes	High risk	Quote: "un‐blinded randomized controlled study" Judgement comment: blinding of participants and personnel not done (face‐to‐face intervention) and the outcome is likely to be influenced by lack of blinding
Blinding of outcome assessment (detection bias) Subjective outcomes	High risk	Judgement comment: insufficient information about blinding of outcome assessment; but due to performance bias (no blinding of participants), the review authors judge that the participants' responses to questionnaires may be affected by the lack of blinding (i.e. knowledge and beliefs about intervention they received)
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "After this random allocation, students were asked by email to consent to participate in the group to which they had been assigned. A proportion of students declined to participate (as indicated below), and were replaced by other students selected at random in a similar fashion from the remaining members of the class on a rolling basis until a complement of 30 control and 29 study participants was achieved." Quote: "One study participant dropped out during the first week for scholastic reasons and his data were not used." Judgement comment: information received from authors: “We had: 30 controls, 29 treatment at the start of the study. By the end, because of attrition of one individual from each arm we had 29 controls and 28 study subjects = 57 participants total analyzed”; reasons for missing data unlikely to be related to true outcome with relative balance in missing data between groups (12 in CG refused to participate in allocated group after randomisation vs 10 in IG); participants who dropped out were replaced by other students in the class; 2 dropouts during intervention phase (IG: 1, CG: 1); per‐protocol analysis analysis (only participants who took part in allocated intervention)
Selective reporting (reporting bias)	Low risk	Judgement comment: no study protocol available but it is clear that the published reports include all expected outcomes, including those that were prespecified