Cytomegalovirus pp65 antigenaemia as an indicator of end-organ disease in AIDS.

We aim to assess the usefulness of the cytomegalovirus (CMV) pp65 antigenaemia test, also called the CMV direct antigen test (DAT), in the management of patients with advanced human immunodeficiency virus (HIV) infection; we studied all patients who had pp65 assays between 8 September 1995 and 30 August 1996. Twenty-three patients had 31 tests. The mean CD4 cell count was 20/mm3. The tests were negative in 16 patients, of whom 12 have not developed CMV end-organ disease after a mean follow up of 114 days (range 14-269 days), whilst the remaining 4 patients had previously treated CMV disease. Eleven patients had positive tests: 4 had active CMV disease, 2 subsequently developed CMV retinitis, 2 died within a fortnight of multi-drug resistant tuberculosis (MDR-TB), one was lost to follow up and 2 have remained disease-free. This test has a positive predictive value of 43% and a negative predictive value of 94%, Fisher's exact test P=0.03. The pp65 antigenaemia assay can be performed in a standard virology laboratory avoiding the problems associated with polymerase chain reaction (PCR), a result is available within 5 h, and it is semi-quantifiable. However, a large prospective study is required to determine the comparative value and roles of the pp65 antigenaemia assay and DNA PCR in the management of CMV disease, especially with regard to the use of primary prophylaxis and pre-emptive therapy.