Ma 2003.

Methods	Randomized, double‐blinded, double‐dummy, active‐controlled Medication administered when baseline pain reached moderate‐to‐severe intensity
Participants	Type of surgery: thoracic and abdominal elective Propacetamol group Entered/completing: 20/20 Age (mean, SD): unclear Sex (male, %): unclear Pethidine group Entered/completing: 20/20 Age (mean, SD): unclear Sex (male, %): unclear
Interventions	Intervention: 2 g propacetamol in 100 ml saline Control: 50 mg pethidine IM
Outcomes	Pain intensity (VAS, VRS) and derived SPID Pain relief (VAS, VRS) and derived TOTPAR Time to onset and duration of analgesia Global evaluation (categorical)
Source of funding	Unclear ‐ one author was an employee of Squibb Pharmaceuticals
Were treatment groups comparable at baseline?	Yes: demographics, disease categories, operation categories, anesthesia methods and duration, vital signs, hepatorenal function, and blood cell count
Details of preoperative pain	Unclear
Notes	Chinese language article with abstract and data in English
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Chinese article ‐ unable to ascertain
Allocation concealment (selection bias)	Unclear risk	Chinese article ‐ unable to ascertain
Blinding (performance bias and detection bias) All outcomes	Low risk	Double‐dummy technique
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Chinese article ‐ unable to ascertain
Selective reporting (reporting bias)	Unclear risk	Chinese article ‐ unable to ascertain
Size	High risk	Fewer than 50 participants per arm of the study (20 propacetamol, 20 pethidine)