Farkas 1992.

Methods	Randomized, double‐blind, double‐placebo, placebo‐ and active‐controlled Medication administered when baseline pain reached at least moderate intensity
Participants	Type of surgery: abdominal aortic repair Propacetamol group Entered/completing: 29/15 Age (mean, SD): 64.3 ± 2.2 Sex (male, %): 3 Dipyrone group Entered/completing: 30/21 Age (mean, SD): 62.4 ± 1.7 Sex (male, %): 20 Placebo group Entered/completing: 30/15 Age (mean, SD): 64.3 ± 1.8 Sex (male, %): 3
Interventions	Intervention: 2 g propacetamol over 2 min Control: 2.5 g dipyrone plus 0.01 g pitofenone IV Placebo: not described
Outcomes	Pain intensity (5‐point VRS) Requirement for rescue analgesia (morphine)
Source of funding	Not reported
Were treatment groups comparable at baseline?	Yes: demographics, baseline postoperative pain score
Details of preoperative pain	Not reported
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomization table
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding (performance bias and detection bias) All outcomes	Unclear risk	"Investigator who did not know the nature of the products, infused the test products to each patient according to their number of entry into the trial. The patients were then monitored in the recovery room over six hours by the same investigator who did not know the nature of the product administered".
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Post‐rescue assessments imputed using LOCF; imbalance amongst groups in number of participants withdrawn due to requirement for rescue analgesia
Selective reporting (reporting bias)	Low risk	All outcomes from Methods section reported in Results section
Size	High risk	Fewer than 50 participants per arm of the study (29 propacetamol, 30 dipyrone, 30 placebo)