Slaven 1998.

Methods	Study design: parallel RCT Study duration: not reported Study follow‐up: 6 h
Participants	Country: New Zealand Setting: single centre Inclusion criteria: healthy as judged by medical history, physical examination, routine biochemical and haematological screening and were rated as American Society of Anaesthesiologists (ASA) classification undergoing elective lower back surgery (laminectomies) Number: treatment group (10); control group (10) Mean age ± SD (years): treatment group (39.6 ± 14.1); control group (38.3 ± 7.2) Sex (M/F): treatment group (10/0); control group (6/4) Exclusion criteria: not reported
Interventions	Treatment group Tenoxicam: 40 mg IV prior to induction Control group Placebo: IV prior to induction
Outcomes	Urinary CrCl, osmolar clearance and free water clearance
Notes	Funding source: tenoxicam‐placebo gift from Roche Products New Zealand Ltd
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation performed by pharmacist, randomisation technique unknown
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Active agent and placebo drugs were delivered to the theatre room in prefilled syringes
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information to permit judgement
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Insufficient information to permit judgement
Selective reporting (reporting bias)	Low risk	Study protocol matches outcomes presented
Other bias	Low risk	The tenocixam‐placebo was a gift from Roche Products New Zealand (the manufacturer). The study design and analysis of the results were independent of any pharmaceutical company involvement.