Secondary causes of inflammatory bowel diseases

Table 1 Classification of secondary inflammatory bowel diseases based on etiology

Classification
Drug-induced secondary IBD	Immunomodulators: Azathioprine, 6-mercaptopurine, tacrolimus, mycophenolic acid, cyclosporine; Anti-TNF agents: Infliximab, adalimumab, etanercept; Anti-interleukin agents: Secukinumab, tocilizumab; Interferons: Interferon α; Immune stimulating agents: GM-CSF (sargramostim), G-CSF (filgrastim); Checkpoint inhibitors: Ipilimumab, nivolumab, pembrolizumab
Post-surgical secondary IBD	Post-colectomy enteritis syndrome; Post-colectomy ileal pouchitis; Post-colectomy de novo Crohn’s Disease of the Pouch; Post-bariatric surgery: Roux-en-Y gastric bypass
Post-transplant secondary IBD	Fecal microbiota transplantation related IBD; Post- hematopoietic stem cell transplant IBD: cord colitis; Post-solid organ transplant IBD: liver, kidney

IBD: Inflammatory bowel disease; GM-CSF: Granulocyte monocyte-colony stimulating factor; G-CSF: Granulocyte-colony stimulating factor.