Serradori 2013.

Study characteristics
Methods	Retrospective, multicenter (3 institutions) cohort. Study period: 2000 to 2010
Participants	Country: France. CD patients who underwent ileocecal or ileocolonic resection. Patients with temporary stomas were excluded.
Interventions	1. Preoperative anti‐TNF within 8 weeks of surgery 2. Preoperative steroids
Outcomes	Intraabdominal abscess, anastomotic leak, fistula within 30 days of surgery
Notes	NOS low risk of bias overall Adjusted ORs for preoperative anti‐TNF and corticosteroids were obtained from multivariate regression analysis.
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	CD patients who underwent ileocecal or ileocolonic resection from 2000 to 2010
Selection of the non exposed cohort	Low risk	Both groups obtained from the same database and time period
Ascertainment of exposure	Low risk	Medical charts reviewed
Demonstration that outcome of interest was not present at start of study	High risk	30 patients had an abscess at the time of surgery
Comparability of cohorts (Controlled for critical factor/other medications)	Low risk	Controlled for steroids and anti‐TNF use
Comparability of cohorts (Controlled for additional factor)	Low risk	Also controlled for age, Montreal classification
Assessment of outcome	Low risk	Medical charts reviewed
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Unclear risk	Information not provided