Brouquet 2018.

Study characteristics
Methods	Prospective, multicenter (19 institutions), cohort study. Study period: 2013 to 2015
Participants	Country: France. Patients with ileocolonic CD who underwent abdominal surgery. Patients with perianal CD or colonic CD were excluded
Interventions	1. Preoperative anti‐TNF therapy (n= 143) within 3 months of surgery 2. No preoperative anti‐TNF therapy (n= 449)
Outcomes	Peritonitis, anastomotic leak, and intraabdominal abscess within 30 days of surgery
Notes	NOS low risk of bias overall Adjusted OR for anti‐TNF medications was obtained from multivariate m odel with propensity s core analysis .
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	All patients who underwent surgery for ileocolonic CD from 2013 to 2015
Selection of the non exposed cohort	Low risk	Both groups obtained from the same database and time period
Ascertainment of exposure	Low risk	Data prospectively collected on an electronic dedicated clinical research form
Demonstration that outcome of interest was not present at start of study	High risk	18% patients had intraoperative finding of abscess
Comparability of cohorts (Controlled for critical factor/other medications)	Low risk	Controlled for systemic steroids and budesonide
Comparability of cohorts (Controlled for additional factor)	Low risk	Also controlled for recurrent CD, hemoglobin, TPN, laparoscopic approach, and operative time
Assessment of outcome	Low risk	Prospectively collected on an electronic dedicated clinical research form
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Unclear risk	No information provided