CMV pp65 antigen testing is of limited utility in the diagnosis of concomitant CMV disease in HIV-infected patients in the HAART era.
BACKGROUND
There are limited data on the utility of the CMV pp65 antigen (Ag) test for the diagnosis of concomitant CMV end-organ disease (EOD) in HIV+ patients in the highly active antiretroviral therapy era.


OBJECTIVE
We sought to assess the predictive value of a single pp65 test for the diagnosis of concomitant CMV EOD in HIV-infected patients.


METHODS
A review of all pp65 Ag tests conducted at a large county teaching hospital from January 1998 through July 1999 was conducted. A diagnosis of CMV EOD required histopathologic evidence (except for retinitis). Concomitant disease was defined as CMV EOD within 30 days of Ag test. Results were reported as number of Ag positive cells/300000 cells counted.


RESULTS
Two-hundred and thirty patient charts (308 antigen tests) were reviewed. The median follow-up time was 334 days. Thirty-two patients had a prior diagnosis of CMV EOD. The most common reasons for testing were fever (45), pneumonia (10), and monitoring for recurrent retinitis (8). Ag tests were positive (range 1-1042 cells) in 51 patients. Twelve patients were diagnosed with concomitant CMV EOD. A diagnosis other than CMV was made in a significant majority of patients (154). The mean initial pp65 level was significantly higher in patients with concomitant CMV EOD versus those without concomitant CMV: 314 cells versus 13 cells, P<0.0001. The overall sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 67, 81, 16 and 98%, respectively. Using a 50-cell cutoff and including only patients with CMV symptoms and CD4<100, improved test accuracy: sensitivity, specificity, PPV, and NPV of 60, 91, 60, and 91%. The CD4 cell count but not the HIV viral load was predictive of CMV EOD.


CONCLUSIONS
The CMV pp65 Ag test is useful in excluding concomitant CMV disease, but has limited utility in the diagnosis of acute CMV disease. The highest test utility will be in patients with a high likelihood of CMV disease based on symptoms, and CD4 cell count.
Skiest
Daniel J
DJ
Division of Infectious Diseases, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9113, USA. daniel.skiest@utsouthwestern.edu
Crosby
Craig
C
D017088:AIDS-Related Opportunistic Infections / Q000097:blood / Q000276:immunology / Q000821:virology*; D000328:Adult; D000956:Antigens, Viral / Q000097:blood*; D018791:CD4 Lymphocyte Count; D003587:Cytomegalovirus / Q000276:immunology / Q000302:isolation & purification*; D003586:Cytomegalovirus Infections / Q000097:blood / Q000175:diagnosis* / Q000276:immunology / Q000821:virology; D015658:HIV Infections / Q000097:blood / Q000150:complications / Q000188:drug therapy; D006801:Humans; D008297:Male; D010750:Phosphoproteins / Q000032:analysis*; D014763:Viral Matrix Proteins / Q000032:analysis*
D000956:Antigens, Viral; D010750:Phosphoproteins; D014763:Viral Matrix Proteins; C065418:cytomegalovirus matrix protein 65kDa