Dilmen 2016.

Methods	Study design: randomized controlled trial (4 arms) Study duration: June 2013 to January 2015 Study setting: hospital, single centre, Turkey
Participants	Adults undergoing elective supratentorial craniotomy (n = 83) Inclusion criteria ASA I to III participants Exclusion criteria Neurological disorders compromising communication Aphasia Drug or alcohol addiction Chronic pain Raised intracranial pressure Allergy to any study drug Liver or kidney dysfunction Dementia Peptic ulcer disease Glasgow coma score < 15 Mean age, range (years) 44 (18 to 70) Numbers allocated to each arm Group 1: dexketoprofen: 18 Group 2: paracetamol :20 Group 3: metamizole: 19 Group 4: saline control: 18 Male gender Group 1: 9/18 Group 2: 11/20 Group 3: 8/19 Group 4: 11/18
Interventions	Technique and timing Bolus intravenous injections of dexketoprofen, paracetamol, metamizole or 0.9% saline were given at skin closure and repeated every 8 hours in the dexketoprofen and every 6 hours in the paracetamol, metamizole and control groups. Dosage Group 1: dexketoprofen 50 mg Group 2: paracetamol 1 gram Group 3: metamizole 1 gram Group 4: saline control: not reported
Outcomes	Primary Pain in the first 24 hours postoperatively as measured by the visual analogue score (measured at 1, 2, 6, 12 and 24 hours) Secondary Postoperative morphine consumption Adverse events: nausea and vomiting, pruritis, rash
Notes	Funding None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: ''patients were randomised to one of four groups using opaque envelopes.'' However, it was not clear how the envelopes were selected to ensure random allocation.
Allocation concealment (selection bias)	High risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: ''the study drugs that were dissolved in 100 mL 0.9% saline solution were prepared by a nurse and administered by another nurse whereas postoperative data were collected by a blinded anaesthesiologist''.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Postoperative data was collected by a blinded anaesthesiologist.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	8 participants were excluded from the analysis. 1 participant: could not be extubated at the end of surgery (did not state which group he or she was in) 2 participants: did not regain consciousness at the end of surgery (both in the metamizol group) 3 participants: suffered seizures (1 in the dexketoprofen group and 2 in the paracetamol group) 2 participants: required merperidine for postoperative shivering (both in the saline control group)
Selective reporting (reporting bias)	Low risk	Outcomes reported as specified
Other bias	Unclear risk	Small study