Screening and diagnostic performance of enzyme immunoassay for antibody to lymphadenopathy-associated virus

In a multicenter cooperative study, an enzyme immunoassay (EIA) using purified antigen of lymphadenopathy-associated virus was compared with radioimmune precipitation (RIP) for detection of antibody to human immunodeficiency virus (HIV) in 634 patients with acquired immunodeficiency syndrome or related conditions, 687 apparently healthy persons at risk for HIV infection, 93 controls with cancer or autoimmune diseases, and 10,038 blood or plasma donors. Excluding the donors, the EIA was reactive in 875 (61.9%) of 1,414 subjects; compared with RIP, the sensitivity and specificity of EIA both were 99.8%. There was one false-positive EIA among 148 intravenous drug abusers and two false-negative EIAs among 472 apparently healthy homosexual men; no other discordant results between EIA and RIP occurred in these subjects. The EIA was repeatably reactive in 20 donors (0.2%), among whom 13 (65%) were positive by RIP; none of 529 randomly selected EIA-negative donors was RIP positive. In addition to its utility as a screening test in low-risk populations, the EIA for antibody to lymphadenopathy-associated virus is useful as a diagnostic test in persons with clinical evidence of or at risk for HIV infection.