Induction Immunosuppression is Associated With a Lower Incidence of Post-transplant Diabetes Mellitus in Heart Transplant Recipients: A Propensity-adjusted Analysis

Introduction: Post-transplant diabetes mellitus (PTDM) is a common complication among heart transplant recipients resulting in heightened risk of diabetes-related complications and death. While there is evidence that certain maintenance immunosuppression drugs like tacrolimus increase the risk of PTDM, it is not known whether induction immunosuppression does the same. We therefore evaluated whether induction immunosuppression in the early post-transplant period with IL-2 inhibitors, alemtuzumab or anti-thymocyte globulin is associated with PTDM after accounting for potential confounding by indication. Methods: Using data from the Scientific Registry of Transplant Recipients, we conducted a cohort study of 23,946 US adults who received a heart transplant in January 2008-December 2018. PTDM was defined as new diagnosis of diabetes at any time 6 months after transplant. We excluded patients with prior organ transplants and diabetes. We used logistic regression to construct propensity scores for predictors of induction immunosuppression and risk factors for PTDM including demographic, clinical and immunologic factors, pre-transplant therapies, steroids, functional status, and transplant year. We estimated the effect of induction immunosuppression in propensity-adjusted Cox proportional hazards models and produced fully adjusted Kaplan-Meier curves using inverse probability of treatment weights. Results: The average age was 54 (SD=12.5) years, 26% were female and 12,303 (51%) received induction immunosuppression. Over 84,969 person-years, 2,678 (11%) developed PTDM (32 cases/1,000 person-years). In the propensity-adjusted analysis, induction immunosuppression was associated with a 20% lower rate of PTDM (Figure 1; hazard ratio=0.80, 95% confidence interval 0.74-0.87). Conclusions: Adult heart transplant recipients who received induction immunosuppression had a 20% lower rate of PTDM compared to those who did not receive it.