Cakan 2008.

Methods	Randomized, double‐blind, placebo‐controlled, over 24 h Medications administered during skin closure
Participants	Type of surgery: elective lumbar laminectomy and discectomy Paracetamol group Entered/completing: 20/20 Age (mean, SD): 41 ± 10 Sex (male, %): 60 Placebo group Entered/completing: 20/20 Age (mean, SD): 44 ± 10 Sex (male, %): 55
Interventions	Intervention: paracetamol 1 g IV over 15 min Placebo: 100 ml normal saline
Outcomes	Pain intensity at rest or movement (VAS) Opioid consumption (morphine) All other outcomes reported at 24 h only
Source of funding	Not reported
Were treatment groups comparable at baseline?	Yes: demographic data (sex, age, duration of surgery, intraoperative opioid use) and vital signs
Details of preoperative pain	Not reported
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated block randomization
Allocation concealment (selection bias)	Low risk	Sealed, opaque envelopes
Blinding (performance bias and detection bias) All outcomes	Low risk	Placebo administered in same solution over same time period
Incomplete outcome data (attrition bias) All outcomes	Low risk	It appears that all participants completed the study and contributed data for each outcome at all relevant time points
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 (20 paracetamol, 20 placebo)