Comparison of Two Test Methods-NASBA and Antigenemia-for Detecting Cytomegalovirus Infection

Currently, it is the standard of care to use the pp65 antigenemia assay to guide anti-cytomegalovirus therapy in hematopoietic stem cell transplant patients. Nevertheless, over the past two years at our institution, only approximately 10% of antigenemia-positive patients went on to develop overt CMV disease and only 22% of patients with documented clinical CMV disease had a positive antigenemia test in the two weeks prior to diagnosis (data on file). Recently, a test called CMV Real-Time PCR has been applied to the diagnosis of CMV infection. Preliminary data suggests that this test may be of value in detecting active CMV replication. Thus, it may be able to predict CMV disease and help guide antiviral therapy. We propose a prospective observational study comparing CMV Real-Time PCR test and pp65 antigenemia. This will be done by taking an extra blood sample (approximately 5 mL) for the CMV Real-Time PCR test from hematopoietic stem cell transplant patients whenever a sample for the pp65 antigenemia test is drawn. No separate venipunctures are anticipated. These samples will be drawn on an approximately weekly basis during the first 100 days post-transplant, as is currently done for the pp65 antigenemia test alone. Additionally, at any time blood is drawn for the pp65 antigenemia test after 100 days, we will also take blood for the CMV Real-Time PCR test, up to one year post-transplant. The results of the CMV Real-Time PCR test will not be used to guide therapy. Overt CMV disease will be identified via real-time chart review and patient interviews by one of the investigators in the study. The primary goal of the study is to evaluate the ability of the CMV Real-Time PCR test to accurately detect active CMV viral proliferation and predict ultimate overt CMV disease as compared to the currently-used pp65 antigenemia test.