Ardizzone 2004

Methods	Open‐label, single‐centre, randomised, controlled trial
Participants	Crohn's disease patients were enrolled 2 weeks after elective stricturoplasty, minimal bowel resection or both (N = 142) Exclusion criteria included contraindications for use of azathioprine or mesalamine; significant preexisting conditions; the use of immunosuppressive drugs in the past 3 months or anti–tumour necrosis factor within the 6 months before surgery; any corticosteroid‐dependant disease; as well as women who were pregnant, planning pregnancy or breastfeeding
Interventions	Azathioprine 2 mg/kg/day (n = 71) for 24 months or until relapse Mesalamine 3 g/day (n = 71) for 24 months or until relapse
Outcomes	Primary outcomes: clinical relapse (symptoms of active disease with laboratory, radiological or endoscopic findings and CDAI > 200 to warrant steroids) or surgical relapse (symptoms refractory to medical treatment and need for further surgery) at 24 months Secondary outcome: adverse events
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation in blocks of 10
Allocation concealment (selection bias)	Unclear risk	Not clearly described
Blinding of participants and personnel (performance bias) All outcomes	High risk	Open label study
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Unclear with data reported
Selective reporting (reporting bias)	Unclear risk	Unclear with data reported
Other bias	Low risk	None apparent