Bregnbak 2012.

Study characteristics
Methods	Retrospective cohort. Study period: 2005 to 2010
Participants	Country: Denmark. UC patients who underwent colectomy. Patients with colonic malignancy or dysplasia were excluded.
Interventions	1. Preoperative infliximab (n=20) within 90 days of surgery. 2. Preoperative corticosteroids (n=48) 3. No preoperative infliximab (n=51) 4. No preoperative corticosteroids (n=23)
Outcomes	Infectious complications within 30 days postoperative
Notes	NOS very high risk of bias overall
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	All patients with UC based on clinical, endoscopic and histological criteria who underwent colectomy from 2005 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	Danish National Health Reigster and examination of patient records
Demonstration that outcome of interest was not present at start of study	Unclear risk	No information provided
Comparability of cohorts (Controlled for critical factor/other medications)	High risk	Did not control for other factors
Comparability of cohorts (Controlled for additional factor)	High risk	Did not control for other factors
Assessment of outcome	Low risk	Medical records were examined
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Unclear risk	No information provided