Tunali 2013.

Methods	Participants randomized to 3 groups to receive interventions at the time of wound closure (supposedly within 30 min from end of surgery)
Participants	Type of surgery: microsurgical lumbar discectomy and/or laminectomy Paracetamol group Entered/completing: 20/18 Age (mean, SD): 46.39 ± 10.06 Sex (male, %): 33 Placebo group Entered/completing: 20/20 Age (mean, SD): 48.35 ± 9.93 Sex (male, %): 55 Dexketoprofen group Entered/completing: 20/18 Age (mean, SD): 39.17 ± 11.10 Sex (male, %): 38.9
Interventions	All administered IV in 100 ml infused over 15 min All participants used IV PCA with morphine Paracetamol: 1 g every 6 h for 24 h The study states paracetamol but in discussion says “Paracetamol is an IV formulation of a prodrug of acetaminophen and used as a supplemental analgesic to reduce postoperative pain” Dexketoprofen: 50 mg IV every 8 h for 24 h Placebo: 100 ml normal saline every 8 h for 24 h
Outcomes	Primary: pain intensity on 0 to 10 VAS at 0, 1, 2, 6, 12, 24 h post‐op but primary outcome not defined Secondary: sedation on Ramsay score, cumulative PCA morphine consumption at the above time points, adverse effects
Source of funding	No funding
Were treatment groups comparable at baseline?	No: age in dexketoprofen group lower than in 2 other groups; pain at time 0 in dexketoprofen group substantially lower
Details of preoperative pain	Not reported
Notes	Frequency of administration different: every 6 h for paracetamol and every 8 h for dexketoprofen and saline
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	1 person prepared sealed envelopes and another person drew an envelope for each case
Allocation concealment (selection bias)	Unclear risk	Unclear if solutions looked any different
Blinding (performance bias and detection bias) All outcomes	Unclear risk	The treatment frequency is different (3 times daily versus 4 times daily), true blinding not likely, although study data were collected by a blinded anesthesiologist
Incomplete outcome data (attrition bias) All outcomes	Low risk	4 participants were excluded, with reasons given. Outcomes seem to be reported in full.
Selective reporting (reporting bias)	Low risk	All outcomes mentioned in Methods reported in Results
Size	High risk	Fewer than 50 participants per arm of the study (20 paracetamol, 20 placebo, 20 dexketoprofen)