The impact of induction therapy on mortality and treated rejection in cardiac transplantation: A retrospective study

Abstract

Background: Evidence regarding the utility of routine induction therapy on outcomes is not clear. This study aims to evaluate whether induction therapy is associated with a reduced risk of treated rejection and improved overall survival.

Methods: We retrospectively analyzed all adult patients (age ≥ 18 years) that are included in the UNOS database who underwent heart transplantation between 2000 and 2017. Patients with prior transplants and dual organ transplants were excluded. 34,361 patients were included in the final analysis. We assessed the impact of induction therapy with T cell depleting agents (TC-DA), IL2 receptor antagonists (IL2R antagonist) and compared that to no induction therapy using Cox regression models adjusted for propensity scores. The primary outcome measure was all-cause mortality, whereas treated rejection at one year was analyzed as a secondary outcome measure (available in 77% of patients).

Results: A total of 52% of the cohort did not receive any induction therapy. A total of 27% received IL2R antagonist and the rest received TC-DA. Median age of the recipients was 55 (IQR: 46-62) years. A total of 25% of the population were women and 39% were supported on left ventricular assist device therapy at the time of transplantation. Median follow-up was 4.2 (IQR: 1.1-8.5) years with 32% reported mortality. Multivariate analysis with propensity score adjustment showed that TC-DA induction did not have any effect on mortality (HR = 0.98, 95% CI 0.93-1.03, p = 0.48). However, IL2R antagonist was associated with a modestly increased risk of all-cause mortality compared to no induction (HR = 1.06, 95% CI 1.01-1.11, p = 0.02, respectively). A total of 25% of patients were found to have treated rejection at one year, TC-DA induction was associated with reduced odds of rejection at one year (OR = 0.82, 95% CI 0.76-0.88, p < 0.001). However, induction with IL2R antagonist was not found to have a significant impact (OR = 1.03, 95% CI 0.96-1.11, p = 0.36).

Conclusions: Compared to no induction therapy, induction with TC-DA was associated with reduction in risk of treated rejection at 1 year with no effect on mortality and IL2R antagonist was associated with a small but statistically significant increase in mortality without any impact on risk of rejection.

Keywords: heart transplantation; induction therapy; rejection; survival.