Gudsoorkar 2018.

Study characteristics
Methods	Retrospective cohort. Study period: 2015 to 2017
Participants	CD and UC patients who underwent IBD‐related surgery
Interventions	1. Preoperative anti‐TNF medication (n= 20) 2. Preoperative vedolizumab (n= 16) 3. No preoperative biologic therapy (n= 12)
Outcomes	Infectious complications within 30 days
Notes	This study is an abstract. NOS risk of bias very high overall
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	CD and UC patients who underwent IBD‐related surgery
Selection of the non exposed cohort	Low risk	Both groups obtained from the same hospitals and time period
Ascertainment of exposure	Unclear risk	Information not provided
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 adjust for other medications
Comparability of cohorts (Controlled for additional factor)	High risk	Did not adjust for additional factors
Assessment of outcome	Unclear risk	Information not provided
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Unclear risk	Information not provided