Associations between multiple immunosuppressive treatments before surgery and surgical morbidity in patients with ulcerative colitis during the era of biologics

Purpose It is unclear whether immunomodulators or biologics, with the exception of corticosteroids, can be risk factors for postoperative infectious complications of ulcerative colitis (UC). Moreover, many immunosuppressive therapies including some biologics are used mainly to treat UC, and many patients are on multi-agent immunosuppressive therapy at the time of surgery. Therefore, we evaluated the influence of pre-operative multiple immunosuppressive agents on the occurrence of surgical site infection (SSI) in UC during the era of biologics. Methods We reviewed surveillance data from 301 patients who underwent surgery between January 2015 and April 2018. The incidences of SSI and possible risk factors among patients receiving different immunosuppressive therapies were compared and analyzed. Results The incidence of incisional SSI was 6.6%, and that of organ/space SSI was 7.0%. Doses of corticosteroids were significantly decreased because of the recent shift toward the use of biologics. The types and numbers of immunosuppressive agents did not significantly correlate with each incidence. Age ≥ 65 years (odds ratio (OR) 3.0), total prednisolone dose ≥ 9000 mg (OR 2.7), and perioperative blood transfusion (OR 3.6) were shown to be independent risk factors for incisional SSI, whereas duration of surgery ≥ 252 min (OR 3.8), urgent/emergent surgery (OR 2.9), and perioperative blood transfusion (OR 2.6) were identified as independent risk factors for organ/space SSI. Conclusions Although no correlation between pre-operative immunosuppressive therapies, except for corticosteroids, was found, selection bias may have occurred due to treatment before surgery. However, biologics, calcineurin inhibitors, and thiopurines did not affect surgical morbidity in UC.