Low Yield of HIV RNA Testing in HIV-Seronegative Samples in Baltimore STD Clinics

Background:  HIV RNA testing detects HIV in the window period between HIV acquisition and detection by traditional (EIA) antibody testing.  In previous studies, HIV RNA testing of pooled antibody-negative specimens increased the rate of HIV detection by 3.5-10.5%.

Objectives:  To describe costs and benefits of HIV RNA testing of HIV-seronegative specimens from patients seeking HIV testing in Baltimore City Health Department (BCHD) STD program sites.  

Methods:  From 6/06 to 3/08, antibody tests using a third-generation EIA (Bio-Rad's GS HIV-1/HIV-2 Plus O) were performed on serum samples from patients at the BCHD STD clinics.  Antibody-negative samples were combined in pools and tested for HIV RNA using the Amplicor HIV-1 Monitor (Roche).  From mid-2007 to 3/08, this protocol was expanded to field outreach sites, including a needle exchange van and other high-risk sites.  Laboratory and partner notification records were reviewed for program evaluation. 

Results:  From 6/06 to 3/08, the BCHD laboratory performed 60,695 HIV antibody tests; 1,766 (2.9%) were positive by EIA methods, 310 from the STD clinics and 1,456 from outreach sites.  HIV RNA testing of antibody-negative specimens detected 6 additional cases, increasing the diagnostic yield by 0.34%.  Four of these cases came from STD clinics and 2 from outreach sites. No previously unknown HIV cases were detected by contact tracing.  The total program cost was $183,872, or $30,645 for each case detected by HIV RNA.

Conclusions:  The diagnostic yield of the HIV RNA testing program in Baltimore was far lower than that reported by other sites.  BCHD discontinued HIV RNA testing in 2008.

Implications for Programs, Policy, and/or Research:  The utility of HIV RNA testing depends on local HIV epidemiology and on the generation of EIA used.  The diagnostic yield of pooled HIV RNA testing should be evaluated locally before widespread implementation.