Axelsson 2003.

Methods	Randomised, double‐blind, placebo‐controlled, cross‐over study Treatment for 7 days with each intervention, no washout
Participants	Advanced cancer (mainly prostate, pancreas, breast, colorectal), well‐controlled pain (< 4/10), stable opioid doses) receiving oral modified‐release morphine with concurrent paracetamol Excluded: chemotherapy, radiotherapy, strontium therapy within 2 months, started amitriptyline within 1 month, started corticosteroids or NSAIDs within 2 weeks N = 42 (30 completed) Completers: M 19, F 11 Median age 72 years (range 38 to 86) Median PI 2 (range 0 to 3) Median 24‐hour dose morphine 70 mg (range 20 mg to 440 mg)
Interventions	In addition to stable dose of oral modified‐release morphine: Paracetamol 4 x 1000 mg daily Placebo
Outcomes	Average daily PI: NRS (0 to 10) Additional morphine consumed Quality of life at baseline and end of each treatment period At end of study, judgement about in which period pain and QoL was better
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of sequence generation not described
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Method used to blind participants and personnel not described
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Method used to blind outcome assessment not described
Incomplete outcome data (attrition bias) All outcomes	High risk	Completer analysis; 12/42 (29%) did not complete
Selective reporting (reporting bias)	Unclear risk	Protocol not available, report as letter only. All relevant specified outcomes reported
Size	High risk	< 50 participants per treatment arm