Interpretive criteria used to report western blot results for HIV-1-antibody testing--United States.

The Association of State and Territorial Public Health Laboratory Directors (ASTPHLD), CDC, and other organizations (e.g., American Red Cross [ARC] and Consortium for Retrovirus Serology Standardization [CRSS]) have recommended for antibody testing to human immunodeficiency virus type 1 (HIV-1) that duplicate repeat reactive enzyme immunoassay (EIA) screening results be confirmed by a supplemental test. This report examines the variation in Western blot (WB) interpretive criteria reported by laboratories enrolled in CDC's Model Performance Evaluation Program (MPEP) for HIV-1-antibody testing.