Babul 1998.

Methods	Design: Randomised, double blind (double dummy), two‐period cross‐over study. Dose stabilisation using morphine; non‐morphine participants transferred to morphine Duration: 2 x 7 days + dose stabilisation phase Setting: not specified
Participants	Cancer pain N = 27 (22 completed and evaluated) M 13, F 9 Mean age 55 years
Interventions	Morphine CR oral tablet, 12‐hourly Morphine CR suppository, 12‐hourly Dose ratio oral:rectal = 1:1 Non‐opioid analgesics continued Rescue medication: MIR
Outcomes	PI: VAS x 4 daily PPI (6‐point categorised scale: no pain 0, mild pain 1, discomforting pain 2, distressing pain 3, horrible pain 4, excruciating pain 5) Nausea, sedation: 100 mm VAS ‐ spontaneous + investigator‐reported
Notes	Oxford Quality Score: R = 1, DB = 2, W = 1. Total = 4/5
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"randomised". Method used to generate sequence not clearly stated
Allocation concealment (selection bias)	Unclear risk	Method not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Double blind conditions maintained by use of matching placebos"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"Double blind conditions maintained by use of matching placebos"
Incomplete adverse event outcome data‐ patient level	High risk	AEs reported on fewer than 90% participants
Selective reporting bias for adverse events	High risk	'AEs consistent with use of opioid analgesics in patients with advanced cancer'
Size	High risk	< 50 participants per treatment arm