Natural History of Cytomegalovirus (CMV) Infection and Disease Among Renal Transplant Recipients

Overview

Although the accumulated knowledge regarding Cytomegalovirus (CMV) infection increased substantially over the past years, several issues still deserve further investigation. The epidemiology of this disease has been changing, perhaps influenced by new immunosuppressive strategies currently used and growing and widespread use of prophylaxis. The knowledge of the CMV viral load kinetics, using a polymerase chain reaction (PCR-based assay), among renal transplant recipients not receiving any prophylactic therapy will allow the determination of risk factors for and the impact of earlier intervention on CMV infection and disease. The goal is to ultimately improve the clinical outcomes for renal transplant recipients.

Cytomegalovirus (CMV) infection remains one of the most common complications affecting organ transplant recipients, with significant morbidity and occasional mortality. The adverse impact of CMV infection on graft function underscores the importance of CMV on transplant outcomes. CMV prevention strategies have resulted in significant reductions in CMV disease and CMV-related mortality. The reduction in the incidence of "indirect effects" of CMV infection has also been attributed to the use of CMV prevention. Nevertheless, management of CMV infection varies considerably among transplant centers. Two major strategies are commonly used for prevention of CMV: universal prophylaxis and preemptive therapy. Within each of these strategies, significant variation in clinical practice exists, including type of cellular or molecular diagnostics, antiviral therapies, monitoring and criteria for stopping treatment. Although the use of universal prophylaxis has increased since the availability of valganciclovir, there is still a debate regarding the superiority of this strategy over the preemptive approach. Furthermore, this costly therapy or any other CMV prophylaxis is currently not reimbursed by our unified public health system. Therefore our strategy has been to use preemptive therapy. Additionally, because we consider different immunosuppressive regimens according to pretransplant stratified evaluation of risk of rejection, only kidney transplant recipients at high risk to develop CMV infection or disease, i.e., negative recipients of positive organ donors, patients receiving induction therapy with thymoglobulin and patients treated for acute rejection undergo preemptive strategy. Using this strategy, our currently overall incidence of CMV infection or disease is currently 25%. This incidence is higher among recipients who received thymoglobulin induction, tacrolimus and mycophenolate maintenance combination or treatment for acute rejection with either high dose of corticosteroids or thymoglobulin. Because none of the kidney transplant recipients at our institution receive any prophylaxis for CMV infection and because immunosuppressive regimens are selected according to immunological rejection risk, this is the ideal population to investigate the natural history of CMV infection and disease using more recent, sensitive and specific molecular tolls.