Introduction: Cytomegalovirus (CMV) is the most frequent opportunistic infection in the first six months after kidney transplantation (Tx). There are two major strategies used for CMV prevention: preemptive therapy and universal prophylaxis. The objective of this study is to evaluate the results of the preemptive therapy in our service through the incidence of CMV infection and disease at 3 and 6 months after transplantation, the number of treatments and the interval between the antigenemia collection and the beginning of treatment.
Materials and Methods: A retrospective cohort study analyzing 221 adult renal transplant recipients performed between May 2015 and June 2016 and followed up at our service. Data collection was performed by review of medical records and results of pp65 antigenemia from the immunology laboratory. Antigenemia is performed on weekly bases from 30-90 days and fortnightly from 91-180 days after Tx. Cumulative Incidences of CMV infection and disease were analyzed by the Kaplan-Meyer method.
Results: From 221 recipients, 45.2% were female, mean age of 49 years (SD±14.11), deceased-donor in 90.5%.  Induction therapy was used in 216 patients, thymoglobulin in 41.2%, and basiliximab in 58.8%. Maintenance therapy was tacrolimus, mycophenolate and prednisone in 94.1%. All recipients with negative CMV serology (R-), who received the kidney from a donor positive serology (D+), and all patients receiving thymoglobulin induction received intravenous ganciclovir prophylaxis during hospitalization. The cumulative incidence of CMV infection (any positive antigenemia) was 76% at 3 months and 72%, at 6 months, the first infection being 22 days post-Tx. Considering significant viral replication above 10/200.00 polymorphonuclear cells, the incidence was 42% at 3 months and 48% at 6 months. The cumulative incidence of disease was 21% at 3 months and 25% at 6 months. No disease was seen in the first month after transplantation. Gastrointestinal symptoms were the main manifestation. The mean time between the antigenemia collection and the beginning of the treatment was 4 days (CI 95% 3.60-5.07), regardless of the form of communication between the laboratory and the Tx staff. 111 (50.2%) patients were treated with IV ganciclovir. 25 patients presented one relapse and 8 two relapses. From 11 CMV IgG negative serology (R-) patients, only 2 (18.2%) had no viral replication, 3 (27.3%) had 1-10 +cells, 1 (9.1%) had 11-40 +cells and 5 (45.5%) had more than 40 +cells. From 210 recipients with CMV IgG positive serology (R+) pre-transplant, 60 (28.6%) had no viral replication, 34.3% had 1-10 +cells, 20.5% had 11-40 +cells and 16.7% had more than 40 +cells.
Conclusion: The incidence of CMV disease at 6 months post-transplantation was one-quarter of the sample.  We consider that the preemptive therapy was properly performed, with a short time between diagnosis and treatment, avoiding CMV disease in most part of our patients and treatment by half of them.