Analysis of Cornea Transplant Tissue Rejection Delay in Mice Subjects

Abstract

In this paper we present statistical analysis of cornea transplant tissue rejection delay in mice subjects resulting from using one of five types of immunosuppressive agents or placebo. The therapy included FK506 (tacrolimus), MMF (mycophenolate mofetil), AMG (aminoguanidine) and combinations FK506+AMG and FK506+MMF. Subjects were randomized to receiving one of the post-transplant regimens and were followed for up to two months until either rejection of the transplant tissue or censoring occurred. Due to complexity and personnel limitations the trial was performed in four stages using groups of either high risk or regular subjects. We used covariate-adjusted Gray’s time-varying coefficients model for analyzing the time to transplant tissue rejection. At several occasions the type of the outcome (failure or censoring) could not be unambiguously determined. Analyses resulting from the two extreme interpretations of the data are therefore presented, leading to consistent conclusions regarding the treatments efficacy.