Fletcher 1997.

Methods	Randomized, double‐blind, active‐ and placebo‐controlled Medications administered at skin closure (and repeated every 6 h x 48 h)
Participants	Type of surgery: surgery of one herniated lumbar disc Propacetamol group Entered/completing: 15/14 Age (mean, SD): 41.8 ± 2.7 Sex (male, %): 53 Ketoprofen group Entered/completing: 15/14 Age (mean, SD): 49.7 ± 2.9 Sex (male, %): 53 Placebo group Entered/completing: 15/15 Age (mean, SD): 41.8 ± 2.4 Sex (male, %): 60
Interventions	Intervention: 2 g propacetamol in 125 ml dextrose 5% Control: ketoprofen 50 mg Control: combination of ketoprofen with propacetamol (not included in our analysis) Placebo: 125 ml dextrose 5%
Outcomes	Pain intensity at rest and with movement (VAS) Sedation (4‐point categorical scale)
Source of funding	Not reported
Were treatment groups comparable at baseline?	Yes: demographics; preoperative pain; duration of surgery
Details of preoperative pain	Incidence of preoperative leg and/or back pain similar between groups. Mean severity of preoperative pain similar (ranged from 42 to 51/100) between groups.
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Before the study began, a random number table was used to generate a randomized schedule specifying the group to which each patient would be assigned upon entry into the trial
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding (performance bias and detection bias) All outcomes	Low risk	All drugs were administered IV after dilution in 125 ml dextrose 5% labeled with the randomization number of the participant. Participants in all groups received 2 injections to assure blinding.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Low attrition rate balanced amongst groups
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 (15 propacetamol, 15 ketoprofen, 15 placebo)