Mercadante 2000.

Methods	Stated to be randomised but procedure not described. Blinded study: Drugs prepared in identical syringes by a person not involved in the test sessions Placebo control Cross‐over Study duration: 30 to 180 minutes
Participants	Cancer patients with neuropathic pain unrelieved by morphine N = 10 per group (cross‐over) Mean age of patients: 57 years
Interventions	Treatment 1: Saline (IV) Treatment 2: KET bolus 0.25 mg/kg (IV) Treatment 3: KET bolus 0.5 mg/kg (IV)
Outcomes	Pain intensity Adverse effects Results: Low‐dose KET IV + Mo (PO, SC, IV) significantly reduced pain intensity
Notes	Washout period ( "at least two days") Quality/ validity: OPVS score: 12 Oxford score: 3 Information on funding not provided
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Stated to be randomised but procedure not described.
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	"The drugs were prepared in identical syringes by a person not involved in the test sessions". Blinding possibly compromised due to adverse effects from ketamine.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No specific procedure to check for detection bias. Possible bias due to adverse effects from ketamine
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants accounted for
Selective reporting (reporting bias)	Low risk	No problems detected
Size	High risk	Fewer than 50 participants in total (cross‐over)