WP 176 Missed Opportunities for HIV Diagnosis When Using 3rd Generation Rapid Point-of-Care HIV Antibody Testing

Tuesday, June 10, 2014
International Ballroom
Segundo Leon, MT, MT&ID1, Lourdes Ramos Córdova, BS1, Kelika A Konda, PhD2, Juan A Flores, Msc(c) Bioch. & Mol. Biology3, Lottie Romero, MD4, H. Javier Salvatierra, MD5, Brandon Brown, MPH, PhD6, Jeffrey Klausner, MD, MPH7 and Carlos F Caceres, MD, MPH, PhD8, 1Unit of Health, Sexuality and Human Development, and Laboratory of Sexual Health, Universidad Peruana Cayetano Heredia, Lima, Peru, San Martin de Porres, Peru, 2Department of Medicine Division of Infectious Diseases, UCLA, Lima, Peru, 3Unit of Health, Sexuality and Human Development, and Laboratory of Sexual Health, Universidad Peruana Cayetano Heredia, Lima, Peru, 4Unit of Health, Sexuality and Human Development, School of Public Health, San Martin de Porres, Peru, 5Asociación Civil Impacta Salud y Educación, Lima, Peru, 6UC Irvine Program in Public Health, Irvine, CA, 7Division of Infectious Diseases and Program in Global Health, David Geffen School of Medicine and Fielding School of Public Health, Los Angeles, CA, 8Universidad Peruana Cayetano Heredia, Lima, Peru

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 3rd 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 3rd generation HIV antibody R-POC (Determine, Alere Medical Co, Japan). Subsequently, all samples were re-screened using a 4th 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 3rd generation R-POC HIV test and 45 were positive using the 4th generation EIA test (27.3%). Four of those 7 3rd generation R-POC negative/4th 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 3rd generation R-POC should be screened using a 4th generation assay, to avoid false negatives due to the window period. New confirmatory algorithms are needed