Nilsson 2009a.

Study characteristics
Methods	RCT 2‐arm parallel group design
Participants	Adults who underwent CABG or aortic valve replacement Total N randomized: 60 N randomized to music group: 30 N randomized to control group: 30 N analyzed in music group: 28 N analyzed in control group: 30 Mean age: 62 (SD 9.5) years Sex: 13 (22%) women, 47 (78%) men Ethnicity: not reported Setting: inpatient Country: Sweden
Interventions	Two study groups: 1. Music group: participants listened to pre‐recorded music through a music pillow on their first postoperative day 2. Control group: provided a space for rest with reduced environmental stimuli Music provided: Quote from study report (p. 203): "The music was soft and relaxing, 60 to 80 beats per minute, included different melodies in new‐age style for 30 minutes, and played with a volume of 50 to 60 dB". Number of sessions: 1 Length of sessions: 30 minutes Categorized as music medicine
Outcomes	HR: change scores RR, MAP, O₂‐sat: posttest scores S‐Cortisol: change scores Not used: Anxiety (NRS): not included in this review since range of scores but no SDs were reported. Pain (NRS): not included in this review since range of scores but no SDs were reported.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The patients were randomly allocated to 2 groups, 1 music group and 1 control group, using a computer‐generated randomization list created by the statistician" (p. 202).
Allocation concealment (selection bias)	Low risk	Quote: "Three special research nurses allocated the next available number on entry into the trial and conducted all interventions and outcome assessments. The code was revealed to the re‐ searcher once recruitment, data collection, and laboratory analyses were complete" (p.202)
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding of participants was not possible. Personnel were not blinded.
Blinding of outcome assessment (detection bias) Subjective outcomes	High risk	Self report measures were used for subjective outcomes
Blinding of outcome assessment (detection bias) Objective outcomes	High risk	Outcome assessors were not blinded. However, low risk of bias for blood serum cortisol levels as lab technicians were blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition rate: n = 2 (3.3%). Quote: "Two of those patients, who gave informed consent to participate in the music group, were excluded because of chest pain and the drainage procedure" (p. 203).
Selective reporting (reporting bias)	Unclear risk	Not sufficient information available to make judgment
Other bias	Low risk	Funding for this study was provided by grants received from the Research Committee of Orebro County Council.