Alves 2007.

Study characteristics
Methods	Retrospective cohort. Study period: 1984 to 2004.
Participants	Country: France. CD patients who underwent their first ileocecal resection with primary anastomosis. Patients with temporary stomas were excluded.
Interventions	1. Preoperative steroids (n= 59) 2. No preoperative steroids (n=102)
Outcomes	Anastomotic leak and intra‐abdominal abscess within 30 days of surgery
Notes	NOS low risk of bias overall Adjusted OR for st eroids was obtained from stepwise multivariate analysis model.
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	CD database of patients who underwent surgery from 1984 to 2004
Selection of the non exposed cohort	Low risk	Both groups obtained from the same hospital and time period
Ascertainment of exposure	Low risk	CD database
Demonstration that outcome of interest was not present at start of study	High risk	Some patients were found to have Intra‐abdominal abscesses during surgery
Comparability of cohorts (Controlled for critical factor/other medications)	High risk	Did not report controlling for other medications
Comparability of cohorts (Controlled for additional factor)	Low risk	Controlled for poor nutritional status
Assessment of outcome	Low risk	CD database
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Unclear risk	NOS low risk of bias overall