WHO international quality assessment scheme for HIV antibody testing: results from the second distribution of sera.

The WHO international quality assessment scheme for human immunodeficiency virus (HIV) antibody testing has been established to monitor the quality of laboratory performance in testing for antibodies to HIV. Following a small trial distribution of specimens early in 1989, the second distribution was made in February 1990. A total of 20 specimens of sera, 10 of which contained antibodies to HIV-1, were sent to 103 laboratories located in the six WHO Regions. Participants were asked to test the specimens using their routine methods and to report to WHO their findings on each specimen for each diagnostic assay used and their interpretation of the HIV antibody status of each specimen. For the antibody-positive specimens, 98.2% of the results were interpreted as positive and 1.8% as indeterminate; no false-negative interpretations were reported. For the antibody-negative specimens, 90.3% of the results were interpreted as negative, 1.3% as positive, and 8.4% as indeterminate. Most of the indeterminate reports were associated with one particular specimen. A wide variety of diagnostic assays and combinations of assays were used. In terms of the technical results obtained rather than their interpretation, the assays appeared extremely reliable for the positive specimens, with 99.5% of assay results being recorded as positive, 0.17% as negative, and 0.34% as indeterminate.(ABSTRACT TRUNCATED AT 250 WORDS)