Definition of clinical threshold for CMV real-time PCR after comparison with PP65 antigenaemia and clinical data

pp65 antigenaemia and real-time PCR are two methods that are used to diagnose CMV infection in its early stages and, thereby, to facilitate initiation of pre-emptive therapy.

Firstly, to compare PCR with antigenaemia and clinical outcome in order to define a clinical threshold for starting pre-emptive therapy. Secondly, to study the impact of the transplant recipient's serological status on the viral load and on the cut-offs.

Sixty-two patients were analysed using antigenaemia (APAAP method) and real-time PCR. ROC curves were established with antigenaemia or clinical outcome as reference. Patients were divided into primo-infection or reactivation on the basis of the serological status.

PCR correlated better with the clinical data (AUC closer to 1 and best sensitivity, PPV and NPV) than antigenaemia. Furthermore, the performance of qPCR was even better in the reactivation patients.

This work suggests that transplant recipients should be divided according to their serological status. Indeed, replacing antigenaemia by real-time PCR for decisions regarding initiation of pre-emptive therapy is of particular appeal in patients with positive serology. As a result of this work, we have set our clinical threshold at 1500 copies/ml for reactivation.