Kim 2018.

Study characteristics
Methods	Matched cohort study. Enrolment period: unknown
Participants	CD patients who underwent colorectal surgery. Patients matched for age and gender
Interventions	1. Preoperative vedolizumab (n= 13) 2. Preoperative anti‐TNF (n= 39) 3. No preoperative biologic (n= 29)
Outcomes	Surgical site infection within 30 days of surgery
Notes	This study is an abstract. NOS low risk of bias Adjusted OR for preoperative vedolizumab was obtained from a multivariate regression model.
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	CD patients who underwent colorectal surgery
Selection of the non exposed cohort	Low risk	Both groups obtained from the same hospitals and time period. Patients matched for age and gender
Ascertainment of exposure	Low risk	Information obtained from prospective 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)	Low risk	Controlled for age and gender
Assessment of outcome	Low risk	Information obtained from prospective 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