P048 In vitro pancreas toxicity by azathioprine but not 6-mercaptopurine

BACKGROUND: The impact of perioperative use of anti-TNFα on post-operative complications such as infection and wound healing is controversial. There are few studies that reveal relationship between pre-operative serum anti-TNFα concentration and post-operative outcomes in inflammatory bowel diseases. Moreover, perioperative change in serum concentration of anti-TNFα remains to be defined. PURPOSE: The current study assessed perioperative change in serum infliximab concentration of inflammatory bowel diseases and its impact on post-operative surgical site infection (SSI). METHODS: This observation study enrolled 22 ulcerative colitis (UC) and 22 Crohn's disease (CD) patients between January 2010 and October 2013. Patients underwent bowel resections within 8 weeks of last infliximab infusion. Serum samples were collected just before and after surgery, infliximab concentration of each sample was determined by an enzyme-linked immunosorbent assay. The relationships between these concentrations and post-operative SSIs were evaluated. RESULTS: Pre-operative serum infliximab were detected in 12 UC patients (54.5%) and 19 CD patients (86.4%). In UC patients who were detected pre-operative serum infliximab (cut-off value<1.0μg/ dL), there was no significant change from mean pre-operative infliximab concentration (6.20±4.56μg/dL) to post-operative infliximab concentration (5.03±3.88μg/dL) (-18.9%, p= 0.45). On the other hand, in CD patients who were detected pre-operative serum infliximab, there was a significant reduction from pre-operative concentration (5.63±22.5μg/dL) to postoperative concentration (3.93±3.65μg/dL) (-30.2%, p<0.01). SSIs occurred in 4 (19.4%) UC and 6 (27.3%) CD patients. Among 12 UC patients with positive serum infliximab, 3 (25.0%) patients, and 4 of 19 (21.1%) patients in CD developed SSIs. There was no significant difference in the incidence of SSI compared to patients with negative serum infliximab of both patients (UC; 1/9, 10%, p=0.36) (CD; 2/3, 66.7%, P=0.099). Mean pre-operative serum infliximab concentrations with SSIs were 5.78±3.51μg/dL in UC patients and 6.01±4.23μg/ dL in CD patients, there was no significant differences compared with non-SSI groups (UC; 7.46±7.90μg/dL, P=0.93) (CD; 4.04±0.99μg/dL, P=0.76). In addition, no significant association was found between post-operative serum infliximab concentration and with or without SSI in both patients (UC; 4.17±7.60 vs 7.60±7.18μg/dL, p=0.52) (CD; 4.38±3.92 vs 2.26±1.86μg/dL, p=0.32). CONCLUSIONS: Serum infliximab concentrationwas significantly decreased during surgery in patients with CD but UC. However, there was no influence of perioperative serum infliximab concentration on SSI in patients with inflammatory bowel diseases.