Comparison of three assays for cytomegalovirus detection in AIDS patients at risk for retinitis

Assessment of antigenemia assay for the diagnosis of cytomegalovirus gastrointestinal diseases in HIV-infected patients

We conducted a single-center prospective study to evaluate the utility of cytomegalovirus (CMV) antigenemia assay for the diagnosis of CMV-gastrointestinal disease (GID). The study subjects were HIV-infected patients with CD4 count ≤200 μL/cells who had undergone endoscopy. A definite diagnosis of CMV-GID was made by histological examination of endoscopic biopsied specimen. CMV antigenemia assay (C10/C11 monoclonal antibodies), CD4 count, HIV viral load, history of HAART, and gastrointestinal symptoms as measured by 7-point Likert scale, were assessed on the same day of endoscopy. One hundred cases were selected for analysis, which were derived from 110 cases assessed as at high-risk for CMV-GID after endoscopy screening of 423 patients. Twelve patients were diagnosed with CMV-GID. Among the gastrointestinal symptoms, mean bloody stool score was significantly higher in patients with CMV-GID than in those without (2.5 vs. 1.7, p=0.02). The area under the receiver-operating characteristic curve of antigenemia was 0.80 (95%CI 0.64-0.96). The sensitivity, specificity, positive likelihood ratio (LR), and negative LR of antigenemia were 75.0%, 79.5%, 3.7, and 0.31, respectively, when the cutoff value for antigenemia was ≥1 positive cell per 300,000 granulocytes, and 50%, 92.0%, 5.5, and 0.55, respectively, for ≥5 positive cells per 300,000 granulocytes. In conclusion, CMV antigenemia seems a useful diagnostic test for CMV-GID in patients with HIV infection. The use of ≥5 positive cells per 300,000 granulocytes as a cutoff value was associated with high specificity and high positive LR. Thus, a positive antigenemia assay with positive endoscopic findings should allow the diagnosis of CMV-GID without biopsy.

CMV quantitative PCR in the diagnosis of CMV disease in patients with HIV-infection - a retrospective autopsy based study

BACKGROUND

Patients with advanced HIV infection at the time of diagnosis and patients not responding to antiretroviral therapy are at risk of cytomegalovirus (CMV) disease. Earlier studies of patients with HIV infection have demonstrated that the diagnosis is often first made post-mortem. In recent years new molecular biological tests have become available for diagnosis of CMV disease. Although clinical evaluation of tests for diagnosis of CMV disease in HIV-infected individuals is suboptimal without autopsy, no results from such studies have been published. The aim of this study was to explore the diagnostic utility of CMV quantitative polymerase chain reaction (PCR) in plasma from HIV and CMV seropositive patients who died during the period 1991-2002 and in whom autopsy was performed.

METHODS

Autopsy was performed in all cases, as part of routine evaluation of HIV-infected cases followed at Ullevaal University Hospital. Of 125 patients included, 53 had CMV disease, 37 of whom were first diagnosed at autopsy. CMV disease was diagnosed either by ophthalmoscopic findings typical of CMV retinitis, biopsy or autopsy. One or two plasma samples taken prior to the first diagnosis of CMV disease (alive or at autopsy) or death without CMV disease were analysed by CMV quantitative PCR. Sensitivity, specificity, positive and negative predictive values were calculated for different CMV viral load cut-offs and according to detection of viraemia in one versus two samples.

RESULTS

Twenty-seven of 53 patients with CMV disease (51%) and 10 of 72 patients without CMV disease (14%) had detectable viraemia in at least one sample. Sensitivity and negative predictive value (NPV) of the test, maximised with a cut-off at the test's limit of detection of CMV viraemia (400 copies/mL), were 47% and 70%, respectively. With cut-off at 10 000 copies/mL, specificity and positive predictive value (PPV) were 100%. With a requirement for CMV viraemia in two samples, specificity and PPV were 100% in patients with CMV viraemia above the limit of detection.

CONCLUSION

Our results indicate that quantitative CMV PCR is best used to rule in, rather than to rule out CMV disease in HIV-infected individuals at high risk.

Laboratory-based risk factors for cytomegalovirus retinitis

BACKGROUND

Very few studies have investigated risk factors for cytomegalovirus (CMV) retinitis. Identifying these risk factors will have many benefits, including helping establish screening regimens, examination frequency regimens, and targeted prophylaxis with oral therapy with valganciclovir or other anti-CMV agents. The purpose of this study was to determine the laboratory-based risk factors for CMV retinitis in patients with AIDS.

METHODS

We conducted a case-control study involving 120 patients in whom CMV retinitis had been diagnosed in 1990-99 and 159 patients without CMV retinitis from the same period. The sampling was from a primary study base in eastern Ontario and western Quebec of patients with AIDS and CD4 counts less than 50 cells/microL at the time of diagnosis of retinitis in the case subjects or an analogous date for the control subjects. There were two components to the study. In the first component (n = 279) we examined standard-of-care laboratory tests (hematologic and nutrition variables) done during the study period. In the second component (n = 57), which was a subset of the first, we examined laboratory tests (HLA type, qualitative and quantitative CMV polymerase chain reaction [PCR] and HIV load) on stored blood samples from the eastern Ontario site. Multivariate logistic regression was used to model the data and control for confounding. We developed a systematic model-building strategy, from assumption testing to model building to model checking.

RESULTS

A low hemoglobin concentration was a statistically significant predictor of CMV retinitis (odds ratio [OR] 0.96, 95% confidence interval [CI] 0.94-0.98). Both qualitative CMV PCR (OR 21.71, 95% CI 1.80-261.67) and quantitative CMV PCR (OR 33.03,95% CI 2.32-469.39) were strong predictors of CMV retinitis. Among the 80 HLA types tested, HLA-Bw4 (OR 11.68, 95% CI 1.29-105.82) and HLA-DRB115 (OR 9.34, 95% CI 1.14-76.41) were significant predictors of CMV retinitis, whereas HLA-Cw7 was protective against CMV retinitis (OR 0.09, 95% CI 0.01-0.67).

INTERPRETATION

We have identified laboratory variables that elevate (or decrease) the risk of CMV retinitis. These findings may be useful to clinicians and health policy experts in developing rational guidelines for screening, examination frequency and targeted prophylaxis for patients with AIDS.

Comparison of DNA amplification, mRNA amplification, and DNA hybridization techniques for detection of cytomegalovirus in bone marrow transplant recipients

A total of 676 specimens from 63 recipients of bone marrow allografts were tested for cytomegalovirus (CMV) by the following assays: CMV pp67 NucliSens (NS), AMPLICOR CMV MONITOR (RA), and the Digene CMV DNA test (DG). In a consensus analysis, the sensitivities and specificities were 60 and 99% (NS), 96 and 98% (RA), and 90 and 76% (DG), respectively; for detection of symptomatic CMV infection, they were 60 and 97% (NS), 65 and 97% (RA), and 95 and 77% (DG), respectively. In multivariate analysis, the major risk factor for symptomatic CMV infection was an increase in the viral load in the DG assay; in univariate analyses, maximum viral loads in both DG and RA assays and a rising viral load in the RA assay were also significant. The earliest detection of CMV replication was provided by the RA assay (mean, 39 days posttransplantation), followed by the DG assay (mean, 48 days) and the NS assay (mean, 58 days).

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.

OBJECTIVES

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

STUDY DESIGN

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.

Cytomegalovirus (CMV) and human immunodeficiency virus (HIV) burden, CMV end-organ disease, and survival in subjects with advanced HIV infection (AIDS Clinical Trials Group Protocol 360)

We undertook a prospective study to analyze cytomegalovirus (CMV) end-organ disease (EOD) in subjects with advanced human immunodeficiency virus (HIV) infection. Of 403 individuals without prior CMV EOD who were followed up for a median of 151 weeks, 56 died and 21 developed CMV EOD. Twenty of the subjects with CMV EOD had CD4 cell counts of < or =50 cells/mm3 and HIV RNA level of >10,000 copies/mL of plasma at baseline; in these 20 subjects, an increase of CMV DNA level to greater than the quantification limits was associated with CMV EOD. A CD4 cell count of < or =100 cells/mm3 and an HIV RNA level of >10,000 copies/mL of plasma at baseline, a CMV DNA level of >200 copies/mL of blood during follow-up, or development of CMV EOD were all associated with decreased survival. HIV-infected subjects with CD4 cell counts of < or =50 cells/mm3 and HIV RNA levels of >10,000 copies/mL of plasma should have blood fractions screened for CMV DNA; if CMV DNA is detected, CMV prophylaxis might be considered.

Comparison of molecular tests for detection and quantification of cell-associated cytomegalovirus DNA

A cell-based standard was developed to compare the COBAS Amplicor CMV Monitor test, the Hybrid Capture System CMV DNA test, and the NucliSens CMV test. The standard was prepared by infecting human foreskin fibroblasts (HFFs) with cytomegalovirus (CMV) strain AD169 at low multiplicity of infection (0.03) and harvesting the cells at 6 h postinfection. Buffy coat cells were added to produce concentrations of from 0 to 10(5) HFFs per 10(6) total cells. Five laboratories performed the Amplicor PCR test and two laboratories performed the NucliSens and Hybrid Capture tests. The Amplicor PCR test was 1.5 to 2.0 log(10) more sensitive than the Hybrid Capture test. The specificities of the Amplicor PCR and Hybrid Capture tests were 100 and 93.8%, respectively. The linear range of the Amplicor PCR and Hybrid Capture tests were 2 to 4.48 log(10) and 3.48 to at least 5.0 log(10) CMV target cells, respectively. The standard deviations of the Amplicor PCR and Hybrid Capture tests varied throughout their linear range, and for both tests the variability was greater for lower concentrations of input CMV DNA. These data allow the direct comparison of viral load values between the Amplicor and Hybrid Capture tests. The analytical sensitivity of the NucliSens test could not be determined by using the 6-h standard, because the low multiplicity of infection and short culture time did not allow for adequate transcription of pp67 late mRNA measured in the test. Extending the incubation time of the standard to 24 h increased the analytical sensitivity of the NucliSens test to 3.0 log(10) target cells.

HIV and cytomegalovirus viral load and clinical outcomes in AIDS and cytomegalovirus retinitis patients: Monoclonal Antibody Cytomegalovirus Retinitis Trial

OBJECTIVE

To determine the association of cytomegalovirus (CMV) viremia with mortality and CMV retinitis progression in newly diagnosed and relapsed CMV retinitis.

DESIGN

Ancillary study of a randomized, placebo-controlled, phase III clinical trial.

PATIENTS

A total of 83 patients with AIDS and CMV retinitis, enrolled during the first phase of the Monoclonal Antibody Cytomegalovirus Retinitis Trial, were administered MSL-109 or placebo as adjuvant therapy for CMV retinitis.

MAIN OUTCOME MEASURE(S)

Mortality and CMV retinitis progression.

RESULTS

Treatment with MSL-109 did not predict either progression of CMV retinitis or mortality. Detection in plasma CMV DNA at baseline predicted mortality, but CMV antigenemia did not. CMV DNA was a better predictor of mortality than a high HIV viral load. Neither CMV DNA nor antigenemia predicted the progression of CMV retinitis. Among newly diagnosed patients, there was a decline in the proportion with detectable CMV viral load and CMV antigenemia in response to anti-CMV therapy. However, there was a rebound in CMV viral load to 25% and CMV antigenemia to 54.6% at 6 months. In relapsed patients, anti-CMV therapy was not associated with a change in the percentage with detectable CMV-DNA or CMV antigenemia over time.

CONCLUSION

In patients with AIDS and CMV retinitis, the detection of plasma CMV DNA was associated with a higher risk of mortality than was a high HIV viral load. Anti-CMV therapy provided a transient reduction in CMV viremia in newly diagnosed but not relapsed patients with CMV retinitis. Adjuvant therapy with MSL-109 was ineffective in clearing CMV-DNA and CMV antigen from the plasma.

Incremental cost effectiveness of prophylaxis for cytomegalovirus disease in patients with AIDS

Cytomegalovirus (CMV) disease, an opportunistic complication in patients with AIDS, causes substantial morbidity and has high treatment costs. Although prevention of this disease is highly desirable, incremental cost-effectiveness estimates for proposed prophylactic strategies in the era prior to the availability of highly active antiretroviral therapy (HAART) were unfavourable relative to other specific antimicrobial prophylactic strategies in patients with AIDS. With the availability of HAART, several inputs upon which previous estimates of the incremental cost-effectiveness ratio for anti-CMV prophylaxis were based probably changed substantially. To assess the incremental cost effectiveness of prophylaxis in the HAART era, data are needed on visual outcomes and utility for patients with CMV retinitis and AIDS, on better strategies for identifying subpopulations at high risk for CMV disease and on the prophylactic efficacy of valganciclovir. Cost-effectiveness analysis could potentially contribute by exploring thresholds of population risk, prophylactic effectiveness, and drug pricing in order to identify conditions under which prophylaxis for CMV disease in patients with AIDS could potentially become cost effective.

Enteric viruses in HIV-related diarrhoea

HIV-related diarrhoea is an important cause of morbidity and mortality in HIV infection. Cytomegalovirus is a well-established cause of diarrhoea, but the role of other enteric viruses is less clear and will be discussed here. The clinical manifestations, disease mechanisms, diagnostic techniques and current treatments for the management of these infections are reviewed.