Subclinical rejection in the initial postoperative period in small intestinal transplantation : A negative influence on graft survival

Background. Subclinical rejection (SCR) is a known entity in various solid organ transplants but not in intestinal transplantation. Methods. The purpose of this study is to characterize the presence and effect of SCR in small intestinal transplantation (Itx). A total of 151 patients who underwent Itx and maintained a functioning graft for at least 3 months after Itx were investigated. The clinicopathological characteristics associated with a SCR episode within 3 months after Itx were analyzed. Cox regression with the landmark method (the landmark time being 3 months after Itx) was used for the analyses of overall graft survival and cause-specific hazard rate of SCR. Results. A total of 2744 small intestinal transplant biopsies within 3 months after Itx were available for retrospective evaluation; 171 cases (6.2%) were determined as SCR and 78 patients (51.7%) experienced SCR episode within 3 months after Itx. Adult patients were associated with a significantly higher occurrence of a SCR episode (P=0.001). Overall graft survival at 5 years posttransplant for patients experiencing SCR within 3 months posttransplant and for patients without SCR was 37.2% and 60.2%, respectively (P=0.009). Cause-specific hazard rate analysis showed that a SCR episode was associated with a significantly higher hazard rate of death due to infection (P=0.005). Conclusions. A SCR episode in the initial postoperative period of Itx is a significant factor for unfavorable graft prognosis, likely representing alloimmune injury ultimately resulting in patient morbidity due to infection.