Hersch 2016.

Study characteristics
Methods	Study design: randomised controlled trial Study grouping: parallel group
Participants	Baseline Characteristics Web‐based BREATHE Age categories 22‐26, 27‐31, 32‐36, 37‐41, 42‐46, 47‐51, 52‐56, 57‐61, 62‐66 (n(%)): 7 (13%), 7 (13%), 5 (10%), 7(13%), 2 (4%), 9 (17%), 5 (10%), 8 (15%), 2 (4%) Sex (N (% female)): 48 (92%) Sample size: 52 Years of experience (mean ± SD): NR Control (no intervention) Age categories 22‐26, 27‐31, 32‐36, 37‐41, 42‐46, 47‐51, 52‐56, 57‐61, 62‐66 (n(%)): 15 (29%), 2 (4%), 7 (13%), 3 (6%), 4 (8%), 5 (10%), 11 (21%), 5 (10%), 0 (0) Sex (N (% female)): 43 (83%) Sample size: 52 Years of experience (mean ± SD): NR Overall Age categories 22‐26, 27‐31, 32‐36, 37‐41, 42‐46, 47‐51, 52‐56, 57‐61, 62‐66 (n(%)): NR Sex (N (% female)): NR Sample size: 104 Years of experience (mean ± SD): NR Included criteria: Nurses had to be 21 years of age or older and work at one of the participating hospitals 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: the majority of program group participants logged into the program 1 to 3 times. Ten participants in the experimental group never logged into the program. The average number of logins for those who logged in at least once was 2.5. The average amount of time spent in the BREATHE program was 43 minutes. Response rate: of 117 eligible participants 105 participated > 88% Type of healthcare worker: nurses
Interventions	Intervention characteristics Web‐based BREATHE Type of the intervention: Intervention type 4 combination to focus one’s attention on the experience of stress & to focus on work‐related risk factors on an individual level. Description of the intervention: The intervention consisted of seven parts: Welcome and Introduction; Assess Your Stress; Identify Stressors, manage Stress; Avoid Negative Coping; and Your Mental Health. The Manager’s Role includes additional information for nurse managers on identifying workplace stressors and reducing stress through positive management practices. The number of sessions: as often as the target‐group wanted Duration of each session on average: as long as the target‐group wanted Duration of the entire intervention: 3 months Duration of the entire intervention short vs long: short Intervention deliverer: NR Intervention form: Individual (digital) Control (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	Nursing Stress Scale Outcome type: ContinuousOutcome Symptoms of distress Outcome type: ContinuousOutcome
Identification	Sponsorship source: NR Country: USA Setting: Hospital Comments: NR Authors name: Rebekah K. Hersch Institution: ISA Associates, Inc. Email: rhersch@isagroup.com Address: SA Associates, Inc., 201 North Union Street, Suite 330, Alexandria, Virginia Time period: NR
Notes	Symptoms of distress included in analysis 4.1
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Randomization was conducted using a block randomized design with blocks of 4 and 6. The 0 and 1 within each block were random and the order of the group of 4 and the group of 6 was random. Randomization occurred after each participant completed the pretest question‐ naire. The online questionnaire site was checked every day to determine who completed the pretest each day and individuals were assigned to the next condition on the randomization table as they completed the questionnaire."
Allocation concealment (selection bias)	Unclear risk	Quote: "Once randomization was complete, participants were notified of the condition to which they were assigned (no blinding procedures were employed) and were informed of next steps; experimental group participants were sent a link to the BREATHE program along with a randomly generated username and password and instructions for using the program." 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	Low risk	14 of the 104 randomised participants were lost to follow‐up (1 control group vs 13 intervention group). Missing data were imputated. Missing not at random. We found that the following participants were less likely to respond to the posttest measure: those who reported greater number of days in which they had five or more drinks on the same occasion at pretest, those who reported more drinks per day at pretest, and those who had lower scores on the understanding of depression and anxiety measure at pretest
Selective reporting (reporting bias)	Unclear risk	No trial registration or no study protocol reported, nor did we find one online
Other bias	Low risk	No indication of other sources of bias