Supplementary Table 1.

Risk of bias assessment of the included randomized controlled trial (Lubega et al., 2018)

Parameter	Risk of bias	Reason/quotations
Random sequence generation (selection bias)	Low risk	A computer program was used to generate the randomization sequence by an independent statistician
Allocation concealment (selection bias)	Low risk	Block randomization with a block of 10 used to randomly assign participants to either receive ketamine or morphine in equal numbers for the two groups
Blinding of participants and personnel (performance bias)	Low risk	The mixed drug was labeled with the patient study number and delivered to the research assistant in a transparent syringe (all drugs are colorless liquids)
Blinding of outcome assessment (detection bias)	Low risk	Concealment was achieved by making sure that each syringe was labeled according to sequence-generated codes earlier presented as a list of sequential random treatment codes. The labeled syringes were brought in an opaque carrier envelope to the clinic and handed to the attending nurse who retrieved them with their sticker code number, similar to computer generated number sequence, becoming the patients study number
Incomplete outcome data (attrition bias)	Low risk	The clinical data from all patients were used for ITT analysis
Selective reporting (reporting bias)	Low risk	Protocol is not available, but it is expected that all major outcomes were reported
Other bias	Unclear

ITT – Intention to treat