Analytic results of HIV-1 testing using blind proficiency testing.

The use of blind proficiency testing (PT) to examine analytic performance of human immunodeficiency virus type 1 (HIV-1) antibody testing. A total of 32 hospital, blood bank, public health, and commercial laboratories were included in this study. Test sera were introduced as clinical specimens for HIV-1 testing from private practitioners, group practices, clinics, and hospitals in Southern California. A total of 26 laboratories were located throughout California, with six laboratories located in six other states. Results from 306 enzyme immunoassay screening tests and 192 supplemental tests for HIV-1 were reported. Although one positive specimen was reported as indeterminate in almost 30% of results, screening and supplemental testing performances were excellent, with accuracy levels comparable to performance reported on open PT and performance evaluation surveys in the United States. The indeterminate results were attributed to the interpretive criteria used rather than to laboratory errors. Blind PT can be an important tool in improving the quality of total laboratory testing, the usefulness of laboratory results in patient care, and ultimately the health of the public.