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1994-10-25
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Document 2741
DOCN M94A2741
TI Selection of appropriate strategies for HIV testing.
DT 9412
AU Vercauteren G; van der Groen G; Institute of Tropical Medicine, Antwerp,
Belgium.
SO Int Conf AIDS. 1994 Aug 7-12;10(1):235 (abstract no. PB0369). Unique
Identifier : AIDSLINE ICA10/94369834
AB OBJECTIVE: To evaluate the WHO recommended HIV testing strategies. To
investigate the accuracy of a computer programme to predict the outcomes
of certain test combinations in a defined test algorithm. METHODS: Five
algorithms, including the three WHO algorithms (Lancet 1993;342:87-90),
a fourth algorithm (simultaneous testing of all sera with two different
screening assays A and B, considering A+B+ = positive; AB = negative;
A+B/AB+ = indeterminate) and the conventional algorithm (A+ confirmed
with Western blot) were investigated. The screening results of the 7
different HIV screening tests as mentioned on the WHO bulk purchasement
list (Global AIDS News 1992;1:13) obtained on the same well
characterized serum panel (n = 450; HIV-1+: 42%; HIV-2+: 4.6%) were used
for the retrospective analysis. The outcomes of the five algorithms
using different test combinations were calculated retrospectively and
compared with the outcome of computerized formula (introduced in a Lotus
spreadsheet). The intrinsic sensitivity and specificity of each assay
used in a particular algorithm, the sample size, and the HIV antibody
prevalence, must be introduced in the computer to calculate the outcome
of a particular algorithm. RESULTS: Several test combinations using the
evaluated algorithms are capable to give equally good results as the
conventional algorithm. The cost per sample to obtain these results was
two to ten times cheaper as compared to the conventional algorithm
depending on the alternative algorithm and/or test combination used.
Only by using 2 assays simultaneously, it is possible to increase the
sensitivity of the first assay. The data generated by the computerized
formula were comparable to the data obtained retrospectively. The
computer data predicted a decline in the number of false positives with
an increasing HIV prevalence for each algorithm. We observed also a
decline in the number of false positives from algorithms I towards
algorithm II, III and IV respectively. The accuracy of all investigated
test combinations was above 90% even at low prevalences. CONCLUSIONS:
The computer programme can be used to predict accurately the outcome and
the cost of a certain test combination in a particular algorithm at
different HIV prevalences when the intrinsic sensitivity and specificity
of the assays are known, without actually performing any tests. This can
be a valuable tool for laboratory directors and policy makers in their
choice of HIV assays and their decision of an HIV testing strategy. The
data generated by the computerized formula for the evaluated algorithms
at the different prevalences do support the proposed WHO strategies.
DE Algorithms AIDS Serodiagnosis/ECONOMICS/*METHODS Belgium Comparative
Study Cost-Benefit Analysis Human HIV Infections/*DIAGNOSIS HIV
Seropositivity/DIAGNOSIS HIV Seroprevalence Predictive Value of Tests
Software World Health Organization MEETING ABSTRACT
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).