Lightner 2018 B.

Study characteristics
Methods	Retrospective cohort. Study period 2010 to 2017.
Participants	Country: USA. Adult patients undergoing ileocolic resection with primary anastomosis for Crohn's disease
Interventions	1. Preoperative steroid use 2. Preoperative immunomodulator use 3. Preoperative biologics 4. Dual therapy 5. Triple therapy 6. No preoperative medication
Outcomes	Intra‐abdominal sepsis, defined as an intraperitoneal abscess or anastomotic leak
Notes	NOS very high risk of bias overall Unadjusted ORs for preoperative steroids, immunomodulators and biologics were obtained from univari ate analysis.
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	Retrospective cohort of patients undergoing ileocolic resection for Crohn's disease
Selection of the non exposed cohort	Low risk	Both groups obtained from same centres and time period
Ascertainment of exposure	Low risk	Chart review was performed
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	Unadjusted odds ratios were reported
Comparability of cohorts (Controlled for additional factor)	High risk	Unadjusted odd ratios were reported
Assessment of outcome	Low risk	Chart review was performed
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Unclear risk	No information provided