Schluender 2007.

Study characteristics
Methods	Retrospective cohort. Study period: 2000 to 2005
Participants	Country: USA. UC patients who underwent colectomy. Patients with indeterminate colitis, surgery for dysplasia or carcinoma were excluded
Interventions	1. Preoperative infliximab (n= 17) 2. No preoperative infliximab (n= 134)
Outcomes	Infectious complications within 30 days of surgery
Notes	NOS very high risk of bias overall
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	UC patients who underwent colectomy from 2000 to 2005
Selection of the non exposed cohort	Low risk	Both groups obtained from the same database and time period
Ascertainment of exposure	Low risk	Information obtained from a prospectively maintained database
Demonstration that outcome of interest was not present at start of study	Unclear risk	Information not provided
Comparability of cohorts (Controlled for critical factor/other medications)	High risk	Did not control for other medications
Comparability of cohorts (Controlled for additional factor)	High risk	Did not control of additional factors
Assessment of outcome	Low risk	Information obtained from a prospectively maintained database
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Unclear risk	Information not provided