Tzivanakis 2012.

Study characteristics
Methods	Retrospective cohort. Study period: 2000 to 2010
Participants	Country: UK. CD patients who underwent ileocecal and ileocolic resection. Strictureplasties, mulitple resections, subtotal or isolated colonic resections were excluded
Interventions	1. Preoperative steroids (n= 56) 2. No preoperative steroids (n= 117)
Outcomes	Anastomotic leak, intraabdominal abscess, fistula within 30 days of surgery
Notes	NOS low risk of bias overall Unadjusted OR for preoperative corticosteroids was ob tained from regression analysis.
Risk of bias
Bias	Authors' judgement	Support for judgement
Representativeness of the exposed cohort	Low risk	CD patients who underwent ileocecal and ileocolic resection from 2000 to 2010
Selection of the non exposed cohort	Low risk	Both groups obtained from the same hospital and time period
Ascertainment of exposure	Low risk	Data from propsective database that was audited weekly to ensure accurate entry of data
Demonstration that outcome of interest was not present at start of study	High risk	Preoperative abscess was found to an independent predictor of anastomotic‐associated complication
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, sex, malnutrition, preoperative serum albumin, smoking, urgency of surgery, mode of surgery, presence of abscess or fistula at the time of surgery and previous resection for CD
Assessment of outcome	Low risk	Data from propsective database that was audited weekly to ensure accurate entry of data
Was follow‐up long enough for outcomes to occur	Low risk	30 days
Adequacy of follow up of cohorts	Unclear risk	Information not provided