Prevalence of HIV infection in childbearing women in Scotland: A project testing inborn errors screening cards for HIV-1 antibodies

The aim was to assess the heterosexual spread of HIV-1 in Scotland, by Unlinked-Anonymous antibody testing of childbearing women, using residual Guthrie card blood samples. Methods: Between January 1990 and December 1994, 323,948 Guthrie samples were screened for HIV-1 antibody using a modified particle agglutination technique (MAT), with confirmation by antibody capture ELISA and Western Blot. Quality control (Centers for Disease Control and Prevention, Atlanta and the Public Health Laboratory Services, London) confirmed the MAT assay to be 100% sensitive (277/277). The positive predictive value of MAT was 95% (95/101). District postcode and quarter of infant birth, allowed alignment with other studies. Local ethics committees (19/20) allowed testing of 99.6% of Scottish births until June 1993 when the last committee gave consent. In 1991, 99.86% (95%Cl 99.78, 99.94) of Scottish neonates were screened for Inborn Errors of Metabolism. A pilot study, between July and September 1992, concurrently screened 13,858 routine Guthrie cards for antibody to Hepatitis B core antigen. Results: The prevalence of HIV infection in childbearing women in Scotland remained at 0.3/1000 (95% Cl 0.24, 0.36). A significant increase (p