Reports on HIV/AIDS: 1990

JUNE 8, 1990, MMWR, Vol. 39, No. 22, pp.380-383
Editorial Note: Assuring accurate results in tests for HIV-1 antibody remains a critical
component of surveillance for HIV-1 infections. Results from proficiency testing
programs can measure the operational performance of participating laboratories but
must be interpreted cautiously. HIV-1 proficiency testing programs rarely use fresh
single-donor specimens from persons who may or may not be infected with HIV-1.
Because of the necessity to use large volumes of sample materials, proficiency testing
programs often use pooled human plasma samples and dilutions of single reactive
plasma samples in HIV-1-antibody-negative serum. These samples may react nonspecifically and may be difficult to test and interpret. Despite limitations, proficiency
testing is capable of identifying problems with particular types of samples, with
particular tests, with reagents of kit manufacturers (2), and with interpretations and
reporting of testing results (3). Proficiency testing can also serve as a valuable
education tool.
The MPEP incorporates useful elements of proficiency testing programs but also
contains features, such as frequently using single-donor undiluted plasma for samples, that avoid some of the problems encountered by proficiency testing programs.
By using survey data, the MPEP can evaluate parameters such as analytic sensitivity
and analytic specificity for particular HIV-1 tests along with laboratory characteristics
such as laboratory type.
EIAs have proven valuable for screening donated blood for HIV-1 antibody to
reduce HIV-1 transmission through blood transfusions and administration of clotting
factors. In addition, an EIA is usually the first step in diagnosing HIV-1 infection. Thus,
maintaining high analytic sensitivity of EIAs is important.
WBs are frequently used as the independent supplemental test of higher specificity
to confirm HIV-1 antibody following repeatedly reactive EIA test results. Possible
reasons for increases in analytic specificity for WBs include improvements in the
intrinsic properties of available tests, increased use of more standardized test
methods, increased experience and training in the use of WBs by laboratory
personnel, and increased use of more standardized interpretive criteria for test
results. The Public Health Service endorsed the WB interpretive criteria for HIV-1
antibody in public health and clinical practice in July 1989 (4), within one month of
the 1989 sample panel evaluation.
Continued monitoring of performance data is important to assure quality performance of HIV-1-antibody tests, particularly if HIV-1 testing trends continue and
testing capabilities and sophistication expand in both the private and public health
sectors.
References
1. Taylor RN, Przybyszewski VA. Summary of the Centers for Disease Control human immunodeficiency virus (HIV) performance evaluation surveys for 1985 and 1986. Am J Clin Pathol
1988;89:1-13.
2. Polesky HF, Hanson MR. Human immunodeficiency virus type 1 proficiency testing: the
American Association of Blood Banks/College of American Pathologists program. Arch Pathol
Lab Med 1990;114:268-71.
3. Benenson AS, Peddecord KM, Hofherr LK, Ascher MS, Taylor RN, Hearn TL. Reporting the
results of human immunodeficiency virus testing. JAMA 1989;262:3435-8.
4. CDC. Interpretation and use of the Western blot assay for serodiagnosis of human immunodeficiency virus type 1 infections. MMWR 1989;38(no. S-7).

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