Varrassi 1994.

Methods	Double‐blind, randomised, placebo controlled trial. Randomisation method: not stated. Five patients withdrew from study. No details about intention to treat analysis or power calculation.
Participants	100 patients undergoing elective cholecystectomy. Exclusions: pregnancy, history of peptic ulceration, coagulopathies, impaired renal function, allergy or intolerance to NSAIDs, alcohol or opioid abuse, children, aged more than 65 years.
Interventions	Rx: ketorolac 30 mg IM before surgery then 2 mg/h IV infusion for 24 hours. Pl: normal saline 1 mL IM then 2 mL/h IV infusion for 24 hours.
Outcomes	Post‐operative serum creatinine
Notes	No pre‐operative serum creatinine data
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear

Rx = Treatment
 Pl = Placebo