Document 0862
 DOCN  M95A0862
 TI    [Predictive values of the usual biologic tests for the detection of
       human immunodeficiency virus infection. Consequences for screening]
 DT    9510
 AU    Gremy F; Salmi LR; Universite de Montpellier I, Faculte de Medecine,
       LUSIEEM,; Hopital Lapeyronie.
 SO    Bull Acad Natl Med. 1995 Feb;179(2):317-31; discussion 331-3. Unique
       Identifier : AIDSLINE MED/95338806
 AB    This paper tries to review what is scientifically known about the
       predictive values of biological tests of HIV infection. The
       epidemiological situation for that infection is characterized by two
       facts: the very high values of sensitivity and specificity which are
       close to unity; the prevalence of seropositivity which is on average--at
       least in western countries--, very low (except for some small specific
       groups). Under those conditions, Negative Predictive Values are always
       very close to unity, and the percentage of false negative tests is
       extremely low. Things are quite different for Positive Predictive Value,
       which varies very rapidly with very small shifts or uncertainties about
       specificity and prevalence. In the case when prevalence is very low
       (general population screening) and at the same time specificity is not
       excellent (that means < 0.99 or even < 0.995), Positive Predictive Value
       is very poor and the proportion of false positive tests rather
       important. Indeed the analysis of scientific literature, using the
       method of best synthesis evidence, reveals numerous discrepancies as to
       the value of specificity among different tests. Figures vary a lot from
       one study to another. It is not obvious which screening strategies are
       concerned by the results, which finally entail a strong statistical
       uncertainty. Finally, the figures published in the literature are given
       by high standard laboratories. One may fear the tests realized in
       routine laboratories are less reliable. As a conclusion, let us say that
       despite their very good quality, the biological tests, when used
       separately, should not be trusted without strong previous criticism when
       applied to samples of the general population. Any biological screening
       should be preceded by a clinical examination, including a precise
       inquiry, in order to detect people at risk, that means with a high prior
       probability. Clinical dialogue has moreover another great interest: it
       allows health consulting and education, and calls for personal
       responsibility for both seropositive and negative subjects. It is the
       best choice of method to reach a high preventive effectiveness.
 DE    English Abstract  Human  HIV Infections/*DIAGNOSIS  *Mass Screening
       Predictive Value of Tests  Sensitivity and Specificity  Statistics
       JOURNAL ARTICLE

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