Power 1992.

Methods	Study design: parallel RCT Study duration: not reported Study follow‐up: 2 POD
Participants	Country: UK Setting: single centre Inclusion criteria: patients undergoing open oesophagogastrectomy for cancer Number: treatment group 1 (10); control group (10) Mean age, range (years): treatment group (65.2, 51 to 76); control group (69.8, 50 to 79) Sex (M/F): treatment group (9/1); control group (8/2) Exclusion criteria: history of peptic ulceration, asthma, previous reactions to NSAID, allergies, evidence of kidney insufficiency, diuretic therapy and recent NSAID ingestion.
Interventions	Treatment group Diclofenac: 75 mg IM at induction then 4 doses (75 mg each) every 12 h for 48 h Control group Placebo: at induction then 4 doses every 12 h for 48 h
Outcomes	Pre‐operative and post‐operative (day of the surgery, 1 day after surgery) measurement of CrCl, SCr, urine output, sodium output, potassium output, number of patients on diuretic or dopamine to treat post‐operative kidney insufficiency
Notes	Funding source: not reported One patient in diclofenac group withdrawn due to low urine output and was later found to have had a reduced preoperative CrCl (45 mL/min). This patient recovered after IV dopamine and frusemide administration. In this study, frusemide 10 mg IV was given if urine flow rate was < 30 mL/h for 2 consecutive periods of 1 h
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Study was reported as randomised; method of randomisation not reported
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Standardised management for intervention and anaesthetic technique and fluid therapy, however unclear how patients and personnel were blinded.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information to permit judgement
Incomplete outcome data (attrition bias) All outcomes	High risk	1 out of 20 patients, randomised to the active study drug group, was withdrawn after 18 h due to oliguria and severe AKI. It is plausible that the effect is enough to induce clinically relevant bias in observed effect size
Selective reporting (reporting bias)	Low risk	Study protocol matches outcomes presented
Other bias	Unclear risk	Insufficient information to permit judgement