Missed Opportunities for HIV Diagnosis When Using 3rd Generation Rapid Point-of-Care HIV Antibody Testing

Background: Rapid point of care testing (R-POC) has been widely implemented and accepted by healthcare workers and populations at high risk for HIV infection. Most screening programs are based on 3^rd generation R-POC technology, with an unknown amount of false negatives

Methods: We conducted an observational study to understand the syphilis and HIV epidemic among men who have sex with men (MSM) in Lima, Peru. Blood samples were collected and tested for HIV infection using an algorithm that included an initial 3^rd generation HIV antibody R-POC (Determine, Alere Medical Co, Japan). Subsequently, all samples were re-screened using a 4^th generation Ag/Ab HIV EIA serum test (Genscreen ULTRA HIV Ag-Ab, Bio Rad, Redmond, WA). All positive results were confirmed using Western Blot (WB) (Genetic Systems HIV-1 Western Blot, BioRad, Redmond, WA). R-POC results were provided to participants along with post-test counseling and referral the same day of testing, and Enzyme-immunoassay screening and Western Blot confirmatory results were delivered two weeks later

Results: Of 172 participants tested for HIV, 40 (23.3%) were positive using the 3^rd generation R-POC HIV test and 45 were positive using the 4^th generation EIA test (27.3%). Four of those 7 3^rd generation R-POC negative/4^th generation EIA positive participants had negative HIV WB tests; 1 was indeterminate on WB. HIV EIA testing increases HIV case detection by 10% when used as a second screening test

Conclusions: In high-risk populations samples tested for HIV antibody based on 3^rd generation R-POC should be screened using a 4^th generation assay, to avoid false negatives due to the window period. New confirmatory algorithms are needed