All subjects who meet the inclusion criteria and none of the exclusion criteria will be eligible to participate. As the study is non-interventional, no protocol-mandated treatment or management plan will be imposed. In the absence of a universally ac-cepted paradigm for post-transplant monitoring with molecular diagnostics, participat-ing sites will be encouraged to follow their usual practice, supplemented where ap-propriate by the suggested TruGraf and TRAC™ algorithms.
To evaluate both the prognostic performance and the clinical utility of these bi-omarkers, a hybrid analytic framework will be used. Biomarker results will be made available to clinicians in real time, and investigators will prospectively record whether each result led to a change in clinical management. Natural History Subgroup: Test-ing events in which both TruGraf® and TRAC results are double-negative and no change in management occurred. Analyses will be anchored at the test-event level to avoid immortal time bias. This subgroup will be used to evaluate the safety and true negative predictive value (NPV) of a double-negative result, including the incidence of biopsy-proven acute rejection (BPAR) within 30 days.
- Real-World Use Subgroup: Testing events in which biomarker results prompt-ed a change in clinical management (e.g., change in immunosuppression, for-cause biopsy, or enhanced monitoring). By definition, any action following a test result places the event in this subgroup, irrespective of whether the bi-omarker result was double-negative or abnormal. Because clinical actions can alter subsequent risk trajectories, analyses in this subgroup will account for treatment-confounder feedback using causal modeling strategies (e.g., marginal structural models, target trial emulation).