Kulik 2004.

Methods	Study design: parallel RCT Study duration: not reported Study follow‐up: 4 POD
Participants	Country: Canada Setting: single centre Inclusion criteria: patients undergoing elective coronary artery bypass graft Number: treatment group (50); control group (48) Mean age ± SE (years): treatment group (58.9 ± 1.5); control group (60.8 ± 1.4) Sex (M/F): treatment group (46/4); control group (45/3) Exclusion criteria: left ventricle ejection fraction < 20%; SCr > 130 μmol/L; preoperative use of H2 antagonists, proton pump inhibitors, steroids, NSAIDs (with exception of aspirin), narcotics or illicit drugs; history of peptic ulcer, liver disease or NSAID allergy
Interventions	Treatment group Naproxen: 500 mg rectal suppository within 1 h after arrival in the recovery room, then every 12 h for a total of 5 doses; followed by 250 mg orally 3 times/d for 2 days Control group Placebo: suppositories and tablets administered in a similar way as the treatment group
Outcomes	Pre‐operative and post‐operative SCr, inotropic use for kidney dysfunction
Notes	16 patients withdrawn: 7 did not receive naproxen because of prolonged cardiopulmonary bypass time, perioperative stroke, anorexia and protocol violations; 9 did not receive placebo because of cardiac arrest, perioperative MI, elevated baseline SCr, excessive chest tube output and protocol violations Funding source: no funding received
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computerised randomisation
Allocation concealment (selection bias)	Low risk	Medication was prepared by hospital pharmacy and appeared identical
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Medication administration and data collection were done in a double blinded fashion
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Medication administration and data collection were done in a double blinded fashion
Incomplete outcome data (attrition bias) All outcomes	High risk	16 of 98 patients withdrawn from the study, of these one patient had a baseline creatinine of 115 µmol/L pre‐operatively. Remainder of the reasons for missing outcome data unlikely to be related to true outcome Despite 16 patients did not receive the intervention as allocated on randomisation ‐ post‐operative results of all 98 patients presented. The plausible effect size among missing outcomes enough to induce clinically relevant bias in observed effect size
Selective reporting (reporting bias)	Low risk	Study protocol matches outcomes presented
Other bias	Low risk	The study appears to be free of other sources of bias