Tsai 2015.

Methods	Study design: parallel RCT Time frame: not reported Follow‐up period: 4 weeks
Participants	Country: Taiwan Setting: single centre (54‐bed dialysis centre within a university‐affiliated medical centre in Taiwan) Inclusion criteria: patients with CKD aged ≥ 18 years without hearing impairment; eligible participants had to be receiving HD in 2 or 3‐hour sessions weekly undergoing regular maintenance HD for > 3 months Number (analysed/randomised): treatment group (32/32); control group (25/32) BDI score at baseline: treatment group (8.78 ± 6.06); control group (11.04 ± 8.74) Mean age ± SD (years): treatment group (64.94 ± 9.51); control group (61.08 ± 11.18) Sex (M/F): treatment group (16/16); control group (12/13) Antidepressant medication: not reported Exclusion criteria: bedridden or hospitalised CKD patients
Interventions	Treatment group Nurse‐led breathing training Control group Waiting‐list (control) Co‐interventions Not reported
Outcomes	Depression BDI‐II: absence of depression (scores of 0 to 9), mild depression (10 to 19), moderate depression (20 to 29), relatively severe depression (30 to 39), and severe depression (40 to 63) HRQoL Medical Outcome Studies 36‐Item Short Form Health Survey (SF‐36) Physical functioning Bodily pain General health Vitality Mental health Role limitation due to physical health problems (role–physical) Role limitation due to emotional problems (role–emotional) Social functioning Sleep quality Pittsburgh Sleep Quality Index (PSQI) Sleep quality Frequency of sleep disturbances Sleep onset latency Sleep duration Wake‐up time Hospitalisation
Notes	Funding source: not reported Trial registration identification number: not reported Corresponding author: P.S. Tsai (ptsai@tmu.edu.tw)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The random allocation sequence was generated using free online software providing randomly permuted blocks and random block sizes". Comment: Investigators describes a random component in the sequence generation that could be considered as low risk of bias
Allocation concealment (selection bias)	Low risk	Quote: "Another independent research assistant who did not participate in participant enrolment, data collection, or data analyses generated the allocation sequence. The allocation sequence was concealed in sequentially numbered, opaque, sealed envelopes that were safeguarded by the primary investigator (one of us, P‐ST) until it was time to assign the participants to groups. The dialysis nurse who delivered the intervention ensured that each envelope was still sealed, wrote a participant’s name." Comment: investigators could not foresee assignment and it could be considered as low risk of bias
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding of participants and/or the investigators was not reported. The methods of intervention and control treatment were physically different. Participants and investigators could be aware on the treatment allocation group
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "This was an outcome assessor–blind, randomisation controlled trial. [...] An independent research assistant (one of us, S‐HT) who was not involved in implementing the intervention and who was blinded to participants’ group allocation performed the outcome assessment." Comment: The outcome assessment was conducted by the assessor who was unaware of the treatment received. We judged the outcome assessment to be at low risk of bias for these outcome measures
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: "Sixty‐four participants were randomised equally to either the intervention or the control group. Three participants in the control group subsequently withdrew because of hospitalisation; and four participants in the control group refused to complete post‐test questionnaires at Week 6. Only the 57 participants who completed the posttest questionnaires were included in the data analysis." Comment: As reported in the flow chart, 0/32 in nurse‐led breathing training group and 7/32 in control group were lost to follow up (> 10% loss to follow up, there was a differential loss between groups)
Selective reporting (reporting bias)	High risk	There was no published protocol for this study. This study did not report many patient‐centred outcomes that might be expected for a study of this type (i.e. fatigue, death, dialysis withdrawal, adverse events)
Other bias	Low risk	No evidence of other sources of bias