Hui 2014.

Methods	Double blinded, randomised parallel placebo controlled study 6MWT
Participants	People diagnosed with cancer, aged ≥ 18 years, with breakthrough dyspnoea > 3/10, ambulatory, Karnovsky score > 50%, on a stable opioid dose 20 participants Mean age 50 years (range 30 to 75 years) 11 female 70% Caucasian, 15% black, 15% Hispanic Exclusion criteria: dyspnoea > 7/10, supplemental oxygen > 6L, delirium, allergy to fentanyl, substance abuse, recent coronary disease
Interventions	Subcutaneous fentanyl, dosed on a sliding scale, dose ranging from 30 mcg to 350 mcg compared to subcutaneous saline Co‐interventions included regular opioids, bronchodilators, steroids
Outcomes	NRS dyspnoea scale Borg fatigue scale Heart rate Respiratory rate Oxygen saturation Blood pressure Adverse events
Notes	The study measured outcomes before and after the 6MWT The study authors concluded that prophylactic fentanyl was safe and improved dyspnoea, fatigue, walk distance, and respiratory rate, and that there was also a large placebo effect The dose is equivalent to 1.5 mg to 9 mg oral morphine
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer randomised sequence generation.
Allocation concealment (selection bias)	Low risk	Allocation was concealed by using a secured Web site that was only accessible to the study pharmacist after participant enrolment.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double blinded. Both the participants and research staff conducting the study assessments were blinded to the study intervention and the randomisation sequence.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Both the participants and research staff conducting the study assessments were blinded to the study intervention and the randomisation sequence.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants completed the study with no loss of follow up
Selective reporting (reporting bias)	Low risk	There was no evidence of selective reporting.
Other bias	Low risk	We judged that this trial appeared to be free of other sources of bias.
Size bias	High risk	This was a parallel trial with 20 participants in each arm (< 50 participants per treatment arm).