Study	Reason for exclusion
Abelson 2018	Compared rates of surgical complications in IBD patients who underwent surgery between 1995 and 2005 vs 2005 and 2013. Did not compare preoperative medications.
Abou‐Khalil 2016	Studied patients with CD who were treated with immunosuppressants compared with those who were not. Authors clarified that the immunosuppressant group included patients treated with any of the following: mycophenolate mofetil, adalimumab, etanercept, azathioprine, cyclosporine, tacrolimus, sirolimus, infliximab, natalizumab, methotrexate and certolizumab pegol.
Achkasov 2015	Reported combined outcome of surgical site infection and parastomal complications. Unable to contact authors to obtain rate of only the infectious complications.
Adegbola 2018	Reported rates of intra‐abdominal septic complications in IBD patients who underwent ileocolonic resection. Did not report pre‐operative medications in patients who developed septic complications and those who did not develop septic complications. Unable to contact author for more information.
Aelvoet 2016	Compared patients treated with vedolizumab to those treated with infliximab.
Andrew 2017	Infectious outcomes were collected within the first 60 postoperative days.
Bafford 2013	Reported overall postoperative complications and not specifically infectious complications. Unable to contact authors for additional information.
Balachandran 2015	Recorded complications occurring within 3 months of surgery.
Benichou 2018	Did not specify number of patients with postoperative infections who were treated with and without anti‐TNF agents.
Bewtra 2013	Recorded complications occurring within 90 days of surgery.
Braun 2018	Did not report postoperative infectious complications.
Bruewer 2003	Did not specify time frame for postoperative complications. Unable to contact authors for confirmation.
Chaparro 2018	Described characteristics and indications for surgical interventions. Did not report postoperative complications.
Chiplunker 2015	No comparison group
Coscia 2012	Reported overall postoperative complications. Unable to contact authors to obtain rate of infectious complications.
Desai 2012	Postoperative infection was a secondary outcome but results were not reported in the abstract. Unable to obtain information from authors.
De Silva 2011	Complications were recorded from time of surgery to time of discharge from hospital. Range or mean length of stay in hospital was not reported. While infectious complications were reported, patients' medications were not specified. Unable to contact authors.
Domenech 2016	No comparison group.
Eisner 2014	Did not specify time frame for postoperative complications. Unable to contact authors for confirmation.
Fronda 1999	Did not specifically report infectious complications.
Fu 2014	Study did not compare rates of postoperative infection in IBD patients treated with different medications
Gamaleldin 2018	Did not report postoperative infections
George 2017	Included patients who did not have a diagnosis of IBD
Gonzalez 2013	Did not report postoperative infections
Grant 2019	Reported rates of wound healing following proctectomy but not postoperative infectious complications.
Gregory 2019	Reported 90 day postoperative infectious complications.
Heimann 1985	Reported postoperative infections but did not report how many of these patients were treated with steroids and how many were not treated with steroids. Unable to contact authors for confirmation.
Hyde 2001	Did not specify time frame for postoperative complications. Unable to contact authors for confirmation.
Justiniano 2019	Only reported postoperative mortality.
Kamel 2019	Reported effect of biologic agents on operative outcomes (length of small bowel resection, intraoperative blood loss and total operative time) but not postoperative infectious complications.
Kasparek 2012	Did not specify time frame for postoperative complications. Unable to contact authors for confirmation.
Kimura 2019	Did not provide rates of postoperative infectious complications for each category of preoperative medication.
Kline 2020	Did not examine relationship between preoperative medications and postoperative infectious complications.
Kotze 2011	Patient population included in Kotze 2017.
Kotze 2017a	Patient population included in Kotze 2017.
Kotze 2018	Comparison group included patients without IBD
Krupa 2012	Did not specify time frame for postoperative complications. Unable to contact authors for confirmation.
Kulaylat 2017	Recorded complications occurring within 90 days of surgery.
Labidi 2018	There was no comparison group.
Lau 2013	Reported rates of postoperative infection in a graph, which was illegible. Unable to contact authors for additional information.
Li 2016	Reported overall postoperative complications but not specifically infectious complications.
Lightner 2017	Significant overlap with patients in Lightner 2018.
Lightner 2017a	Compared vedolizumab treated patients to anti‐TNF treated patients.
Lightner 2018a	Compared patients treated with ustekinumab to patients treated with anti‐TNF medications.
Lightner 2018b	Compared patients treated with vedolizumab to patients treated with anti‐TNF medications.
Lim 2018	Reported surgical trends over time. Did not examine relationship between preoperative medications and postoperative infectious complications.
Melo‐Pinto 2018	Reported overall postoperative complications but not specifically infectious complications.
Monsinjon 2017	Reported overall postoperative complications but not specifically infectious complications.
Nagao 2016	Did not specify time frame for postoperative complications. Unable to contact authors for confirmation.
Novello 2019	Compared patients treated with ustekinumab to patients treated with vedolizumab.
Oh 2014	Mentioned that the rate of infectious complications was similar between treatment and comparison groups but did not actually report the rate. Unable to contact authors for additional information.
Park 2018	Compared patients treated with ustekinumab to patients treated with vedolizumab.
Parrish 2019	Did not compare different preoperative medications. Compared patients treated with ustekinumab with detectable levels before surgery to patients treated with ustekinumab with undetectable levels.
Poylin 2018	Compared patients treated with vedolizumab to those treated with an anti‐TNF agent.
Quade 2013	Reported overall postoperative complications but not specifically infectious complications.
Rizvi 2019	Reported postoperative infectious complications up to 6 months after surgery.
Sahami 2016	Did not specify time frame for postoperative complications. Unable to contact authors for confirmation.
Scarpa 2015	Reported overall postoperative complications but not specifically infectious complications.
Shim 2018	Compared patients treated with ustekinumab to patients treated with anti‐TNF medications.
Shimada 2016	Did not specify time frame for postoperative complications or rate of complications in the comparison group. Unable to contact authors for confirmation.
Stewart 2009	Reported infectious complications in a group of patients on some form of immunosuppression such as infliximab, cyclosporine, prednisone, or azathioprine. Contacted authors for separate rates of infectious complications in patients treated with each of these medications. However, the authors were unable to obtain this data.
Strassle 2017	Included patients with ulcerative colitis, Crohn's disease, or familial adenomatous polyposis.
Stringfield 2016	Lacked a comparison group.
Valizadeh 2017	Reported infectious complications in patients treated with either immunosuppressant medications or steroids. Did not analyse each type of medications separately.
Watson 2018	Reports rates of any postoperative complication but not specifically infectious complications.
Weber 2017	Did not report postoperative infectious complications.
Yamamoto 2016a	Stated that neither immunosuppressive nor biologic therapy prior to surgery was significantly associated with the incidence of septic complications. Also stated that high dose steroid therapy significantly increased the risk of septic complications. Did not report any rates, odd ratio or risk ratio. Unable to contact author for additional information.
Yamamoto 2018	Included patients treated with either anti‐TNF medication or tacrolimus into one group in their analysis.