Quantifying Gamma-Interferon from CMV-Specific CD8+ T Cells Defines Protection Against Clinically Significant CMV Infection in Solid Organ Transplant Recipients: The Quanti-CMV Score

The cutoff value of the commercial interferon (IFN)-γ release assay (QuantiFERON-CMV) proposed by the manufacturer is assumed to be predictive. We aimed to determine the optimal cutoff value for protection against clinically significant cytomegalovirus (CMV) infection within 30 days. We analyzed two different cohorts: adult CMV seropositive kidney transplant (KT) recipients with antithymocyte globulin (ATG) induction from the TIMOVAL study and seropositive lung transplant (LT) patients from the CYTOCOR study. The optimal cutoff value was established using Youden's index. We estimated the predictive capacity of the cutoff value through the AUROC and assessed the diagnostic accuracy of the assay at the different cutoff values. We finally evaluated clinical variables that could improve the predictive ability of the assay on a predictive score. Four hundred-four samples from 130 transplant recipients were analyzed. The optimal cutoff value was ≥2.2 IU/mL for both populations, with a positive predictive value of 99% and 99.5% (95% CI, 98-100%) for KT and LT recipients, respectively. The AUROC of the predictive score was 0.85 (95% CI, 0.73-0.97). Using the proposed cutoff value and the Quanti-CMV score may allow the individualization of preventive strategies and serve as an objective tool to support clinical decision-making.