Cetinkaya 2019.

Study characteristics
Methods	Design: RCT Date of study: February and June 2018 Power calculation: no Inclusion criteria: the inclusion criteria for the study were 65 years of age or older, no complications during the 3 days of the postoperative period, and willingness to participate in the study. Exclusion criteria: the exclusion criteria were mental retardation that hinders communication, dementia (defined as a Mini‐Mental State Examination [MMSE] score of <23), age < 65 years, hearing problem, development of postoperative complications and unable to speak Turkish.
Participants	Sample size: 60 Country: Turkey Setting: orthopaedics clinic in an educational research hospital Age: Mean age 69.86 (± 7.59) Sex: male, 10 (33.3%) in Intervention group, male, 5 (16.7%) in control group Overall: male (15, 25%) Co‐morbidity: there were no differences between groups for the number of chronic diseases, previous surgery or regular use if medication. Dementia: not reported Frailty: not reported
Interventions	Intervention: patients were exposed to music for 3 postoperative days after hip or knee surgery. The patients listening to music were supplied with an Mp3 player in their room, in bed. A separate headset was used for each patient. The patients listened to Acemasiran‐type classical Turkish music. Acemasiran‐type music affects the human brain and provides a sense of creativity of people. Each patient in the intervention group listened to the music for 20‐minute sessions three times a day for 3 postoperative days. Control: routine nursing care – no other description provided.
Outcomes	Outcomes reported: ‐Incident delirium using The Neecham Confusion Scale Outcomes from study not reported: none Frequency of outcomes assessment: three days postoperatively
Notes	Funding source: not reported Declarations of interest: none reported by authors Delirium not excluded at enrolment
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were randomly allocated into two groups by drawing lots using closed envelopes with numbers from 0 to 9. However, authors state – quote: "Those who selected single numbers were allocated to the control group, and those with double numbers formed the intervention group". Assumed to reflect typographical error in the paper.
Allocation concealment (selection bias)	Unclear risk	Unclear how the allocation to groups was concealed based on method used to generate random allocation
Blinding of participants and personnel (performance bias) All outcomes	High risk	Patients receiving the intervention were supplied with an MP3 player in their room, blinding not possible. States nurses were blinded, although their role in study is unclear.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Those in the intervention group visited by the researcher. States statistician was blinded to assignment, but role of researcher and statistician not defined in terms of outcome assessment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All outcome data reported – no losses to follow‐up
Selective reporting (reporting bias)	Unclear risk	No published protocol available for review
Other bias	Low risk	No evidence of other bias