Background: Detection of acute HIV infection should be a central concern for HIV prevention. HIV 4th generation P24 Ag/HIV Ab testing allows for timely diagnosis of acute infection. AIDS Healthcare Foundation (AHF), the nation’s largest provider of HIV care, evaluated 4th generation testing versus standard rapid antibody testing with pooled RNA testing for the detection of HIV infection and linkage-to-care.
Methods: Beginning May 30, 2013, all male clients who reported having sex with male partners presenting for HIV/STD testing at 4 AHF Los Angeles health clinics were offered routine rapid HIV antibody testing (Insti, bioLytical Laboratories, Richmond, Canada). Clients with a negative rapid HIV test received pooled HIV RNA testing (PCR Roche, Branchburg, NJ) and 4thgeneration HIV P24 antigen/antibody testing (Abbott Architect i1000, Abbott Park, IL).
Results: As of October 4, 2013, 13 (1.4%) of 917 clients tested positive by the rapid HIV test (8), 4th generation P24 Ag/HIV Ab test(5) or pooled HIV RNA testing (4). Four of the 13 were confirmed as acutely infected increasing HIV case detection by 50%. The 4th generation test missed no acute cases but had one false positive result. Of the 12 HIV-infected , 9 were linked to care, 2 have not been linked, and 1 was previously diagnosed. Of the 4 with acute infection, all are on treatment with reductions in HIV viral load. The average time from specimen collection to result availability among those with acute infection was 2.4 days for 4th Generation testing and 12.5 days for NAAT (p < 0.01).
Conclusions: The use of 4th generation HIV testing substantially increased HIV case detection and identified cases of acute infection faster than pooled HIV RNA testing. HIV testing organizations should consider the use of testing methods that provide enhanced and timely case-identification in order to increase community-level serostatus awareness and accelerate linkage-to-care.