HIV RNA testing appears unnecessary for patients taking oral PrEP

Although U.S. clinical guidelines recommend regular provision of HIV RNA testing in people who are on oral HIV pre-exposure prophylaxis (PrEP), such additional testing appears to offer virtually no benefit over faster and cheaper antigen/antibody testing in identifying early HIV acquisition, according to a newly published analysis from Centers of Disease Control and Prevention (CDC) researchers.

Highlighted Study Population and Methods

This study examined changes in the real-world application and effectiveness of HIV testing among oral PrEP recipients after the issuance of the 2021 updated CDC clinical guidelines for HIV preexposure prophylaxis (PrEP), which recommended both HIV antigen/antibody (Ag/Ab) testing and HIV RNA (i.e., viral load) testing at PrEP initiation and during routine follow-up.

A cohort consisting of 26,044 individuals who initiated oral PrEP between January 2019 and June 2023, and who had corresponding laboratory data, was constructed utilizing the HealthVerity master database. (This database comprises de-identified insurance claims, electronic medical records, HIV-related laboratory testing records, and prescriptions from over 20 major vendors, encompassing more than 200 million individuals in the United States.)

The study focused on analyzing:

• The quantity and type of HIV screening tests conducted before and after the 2021 CDC PrEP guidelines update.

• The concordance between Ag/Ab and RNA testing pre- and post-update.

• The false positive rate and positive predictive value of Ag/Ab and RNA testing compared with adjudicated HIV infection results.

Key Findings

• HIV RNA test rate increased from 16 to 123 per 100 person-years after guideline update.

• HIV RNA test positivity rate dropped from 1.39% to 0.22%.

• Agreement between Ag/Ab and RNA results remained high.

• False-positive rates of Ag/Ab and RNA tests were similar.

• Positive predictive value of RNA testing for PrEP follow-up fell from 100% to 67%.

• An estimated 8,226 to 9,900 RNA tests were needed to identify one early HIV diagnosis that would be missed by Ag/Ab testing alone.

Read expert analysis from Benjamin Young, M.D., Ph.D. here.