Shin 2020.

Study characteristics
Methods	Study design: randomised controlled trial Study grouping: parallel group
Participants	Baseline characteristics Patchouli Age (mean ± SD): 26.4 ± 3.1 Sex (N (% female)): 25 (100%) Sample size: 25 Years of experience (mean ± SD): 3.7 ± 2.2 Control (placebo) Age (mean ± SD): 26.6 ± 3.4 Sex (N (% female)): 25 (100%) Sample size: 25 Years of experience (mean ± SD): 3.6 ± 2.4 Overall Age (mean ± SD): 26.5 ± 3.2 Sex (N (% female)): 25 (100%) Sample size: 50 Years of experience (mean ± SD): 3.7 ± 2.3 Included criteria: participants were included if they (1) understood the purpose of this study and agreed to participate voluntarily, (2) had been a nurse in the emergency room for at least 6 months, (3) did not have any disease and were not being treated for illness, (4) were not pregnant, (5) did not have an abnormality in olfactory function, (6) did not have asthma or an allergic reaction to patchouli oil, (7) were not receiving stress management such as an exercise or massage program, (8) had never received aromatherapy, and (9) were not regularly taking any medication that was likely to affect mental health status. Excluded criteria: NR Pretreatment: There were no significant differences between the groups in age, gender, body mass index, marital status, education, religion, duration of nursing career, duration of serving as emergency nurses, and experience of traumatic events. Compliance rate: 83% Response rate: 100% Type of healthcare worker: exclusively emergency nurses
Interventions	Intervention characteristics Patchouli Type of the intervention: Intervention type 2 ‐ to focus one’s attention away from the experience of stress Description of the intervention : Patchouli oil was purchased from Aromarant Co. (Rottingen, Germany), and its composition was analyzed by gaschromatography/mass spectrometry and capillary column(HP‐INNOWAX; Agilent Technologies, USA) before administration. The carrier gas was helium, maintained at a rate of 1.0 mL/min. The initial column temperature was 40C,increasing 3C/min to a maximum of 230C. Phytochemical compounds were identified by their relative retention time, and their identities were confirmed by comparison with reference data. The three most abundant compounds were patchouli alcohol, d‐guaiene, and a‐guaiene (Table 1). In the patchouli group, a 0.5 mL aliquot of 5% patchouli oil dissolved in sweet almond oil (used as solvent, control group) was dropped onto a piece of gauze, measuring 5 mm· 10 mm. The gauze was positioned in the philtrum. Each participant took three deep breaths and was subsequently allowed to inhale the essential oil for 20 min through natural breathing. The length of the study intervention was established based on the results of a previous study. The number of sessions: 2 Duration of each session on average: NR Duration of the entire intervention: 2 days Duration of the entire intervention short vs long: Short Intervention deliverer: investigator Intervention form: Group Control (placebo) Type of the intervention: Placebo Description of the intervention : In the control group, a 0.5 mL aliquot of pure sweet almond oil was dropped onto a piece of gauze, and subjects inhaled this oil in the same manner. The number of sessions: 2 Duration of each session on average: NR Duration of the entire intervention: 2 days Duration of the entire intervention short vs long: Short Intervention deliverer: investigator Intervention form: Group
Outcomes	ProQOL ‐ Compassion satisfaction Outcome type: ContinuousOutcome Professional quality of life scale‐IV ‐ Compassion fatigue Outcome type: ContinuousOutcome ProQOL ‐ Burnout Outcome type: ContinuousOutcome Stress (VAS) Outcome type: ContinuousOutcome
Identification	Sponsorship source: This work was supported by a grant from the Basic Science Research Program through the National ResearchFoundation of Korea (NRF‐2018R1D1A1B07050048) and the Institute of Nursing Research, Korea University Grant. Country: Korea Setting: University hospital Comments: NR Authors name: You Kyoung Shin Institution: Department of Basic Nursing Science, College of Nursing, Korea University, Seoul, Republic of Korea Email: NR Address: NR Time period: May to August 2018
Notes	VAS Stress Included in analysis 2.1
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Therefore, 60 subjects were recruited and randomly assigned to the two groups by an investigator using a random number table."
Allocation concealment (selection bias)	Low risk	Quote: "To conceal the allocation sequence, generation of the random allocation sequence and recruitment of participants were conducted by independent investigators."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Participants were blinded to the type of essential oil they inhaled to avoid any placebo effect and were not informed of the study group to which they were allocated."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Participants were blinded and outcomes are self‐reported.
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: "Of the 60 subjects recruited to this study, 10 discontinued interventions and were therefore excluded. Thus, 50 subjects were included, 25 in 5% patchouli oil (patchouli) group and 25 in sweet almond oil (control) group (Fig. 1)." No intention‐to‐treat analysis.
Selective reporting (reporting bias)	Low risk	Trial registration KCT0004615. No indication of selective reporting
Other bias	Low risk	No indication of other source of bias