Document 0312
 DOCN  M9550312
 TI    Using time of first positive HIV test and other auxiliary data in
       back-projection of AIDS incidence.
 DT    9505
 AU    Marschner IC; Department of Biostatistics, Harvard School of Public
       Health,; Boston, MA 02115.
 SO    Stat Med. 1994 Oct 15-30;13(19-20):1959-74. Unique Identifier : AIDSLINE
       MED/95148995
 AB    Estimation of HIV incidence by the method of back-projection typically
       uses data on the time of diagnosis of AIDS cases, together with known
       information about the incubation distribution of AIDS. This paper
       discusses back-projection using auxiliary data on AIDS cases,
       particularly the time of first positive HIV test. We discuss the
       possibility that certain types of auxiliary data, including time of
       first positive test, can be useful in back-projection because they
       provide extra information about the incubation period of AIDS cases.
       Under a back-projection model, theoretical efficiency calculations are
       given comparing back-projection with and without the time of first
       positive HIV test of AIDS cases. These calculations suggest that such
       data have the potential to significantly improve HIV incidence
       estimates, particularly in the recent past. Smoothed non-parametric
       estimates of both HIV incidence and time-dependent testing rates are
       described. These can be obtained using the EM algorithm, in conjunction
       with a smoothing step or a penalized likelihood. The benefit of these
       methods in practice needs to be assessed as such data become available.
 DE    Acquired Immunodeficiency Syndrome/*EPIDEMIOLOGY  Age Factors
       Algorithms  Human  HIV Infections/DIAGNOSIS/*EPIDEMIOLOGY  HIV
       Seropositivity/*EPIDEMIOLOGY  Incidence  Likelihood Functions  *Models,
       Biological  Poisson Distribution  Risk Factors  Statistics,
       Nonparametric  Time Factors  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).