Brief communication: observations of falsely reactive antigen/antibody HIV screening results in an emergency department setting

False-positive HIV antigen/antibody screening disrupts medical care and has psychological implications for misdiagnosed patients. From 2018 to 2023, our emergency-department screened 102,369 patients for HIV. Among 698 reactive antigen/antibody screens, 582 (83.4%) were confirmed true positives and 116 (16.6%) were false-positive, defined as a reactive antigen/antibody test with an undetectable viral load. Among a series of 13 patients with false-positive results, we evaluated clinical characteristics and conducted repeat testing. False reactivity resolved in 10 (77%) cases while 3 (23%) cases were persistently discordant. False positivity was seen during immune activation states including acute non-HIV infection, autoimmune disease, hematologic conditions, and liver disease.