D'Haens 2008

Methods	Randomised controlled trial at 2 centres
Participants	Adult CD patients were enrolled within 2 weeks of curative ileal or ileocolonic resection with ileocolonic anastomosis (N = 81) Exclusion criteria: Patients with macroscopic evidence of pancolitis or disease proximal or distal to the site of resection or those who had an ileorectal anastomosis or stoma, contraindications for use of azathioprine or metronidazole; alcohol or drug abuse, leucopenia, malignancies or ongoing infectious disease (hepatitis, tuberculosis, AIDS); the use of azathioprine within 2 months of surgery and pregnancy
Interventions	Azathioprine 100 mg/day if patient weight was < 60 kg or 150 mg/day if patient weight was > 60 kg (n= 40) for 12 months (n = 40) Placebo for 12 months (n = 41) All patients received metronidazole 250 mg three times daily or ornidazole 500 mg twice daily for 3 months
Outcomes	Primary outcome: proportion of patients with endoscopic recurrence (> 2 Rutgeers endoscopic score) at 3 and 12 months Secondary outcomes: clinical relapse (CDAI > 250), the severity of endoscopic recurrence and adverse events
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation
Allocation concealment (selection bias)	Low risk	Centralized pharmacy randomisation
Blinding of participants and personnel (performance bias) All outcomes	High risk	Single‐blind: azathioprine dummy was provided in sealed containers so the investigator did not see the pills
Incomplete outcome data (attrition bias) All outcomes	Low risk	Full data reported
Selective reporting (reporting bias)	Low risk	Appropriate data reported
Other bias	Low risk	None apparent