The pp65 antigenaemia test as a predictor of cytomegalovirus-induced end-organ disease in patients with AIDS

Objective: To evaluate the predictive value of pp65 antigenaemia quantitative test for cytomegalovirus (CMV) end-organ disease in patients with advanced HlV infection. Design and patients: A prospective study in AIDS patients or HIV-infected subjects with CD4 count < 150 x 10(6)/I or CD4 percentage < 10% was carried out. Patients with a history of CMV disease or positive viraemia or antigenaemia tests, and subjects under anti-herpes suppressive therapy were excluded. Clinical, ophthalmoscopic, biochemical and virological (antigenaemia test) evaluations were performed at baseline and every 1-3 months until the onset of CMV end-organ disease. Setting: Institutional tertiary care centre. Results: Forty-nine patients were evaluable for this study. End-organ disease was observed in 13 patients, 11 with at least one positive test, two with persistently negative assays. Thirteen patients without CMV disease had at least one positive test, whereas 23 always had negative tests. The 12-month Kaplan-Meier estimate of the incidence of CMV disease in our population was 30.9%, and was 75% in antigenaemia-positive subjects. The negative predictive value (NPV) of the test was 92%, and the positive predictive value (PPV) was 45.8%. However, the NPV of quantitative (> 20 cells) antigenaemia assay was 92.1%, and the PPV was 90.9%. Conclusions: The antigenaemia test is a quick, simple and easy to perform assay for diagnosing CMV infection. The NPV is fairly good, as is the PPV when the quantitative method (> 20 positive cells) is used. This test could be used as an alternative to polymerase chain reaction in order to select patients at higher risk of CMV disease who can be treated with pre-emptive anti-CMV therapy.