       Document 0547
 DOCN  M9460547
 TI    Median time from seroconversion to AIDS in Italian HIV-positive
       haemophiliacs: different parametric estimates.
 DT    9404
 AU    Chiarotti F; Palombi M; Schinaia N; Ghirardini A; Bellocco R; Istituto
       Superiore di Sanita-Laboratorio di Fisiopatologia di; Organo e di
       Sistema, Roma, Italy.
 SO    Stat Med. 1994 Jan 30;13(2):163-75. Unique Identifier : AIDSLINE
       MED/94167528
 AB    The purpose of this study was to estimate the median incubation time
       between human immunodeficiency virus (HIV) infection and onset of
       acquired immunodeficiency syndrome (AIDS), using three parametric models
       and six estimates of seroconversion time. Study subjects were 732
       HIV-positive haemophiliacs enrolled in the Italian Registry of patients
       with congenital coagulation disorders. Seroconversion time was estimated
       for each subject according to six different criteria, based on three
       distributions of seroconversion (uniform, uniform on three sub-intervals
       and truncated Weibull) and two indices synthesizing each distribution
       (median and median of three random values). The estimated seroconversion
       times were subsequently used as starting points in the analysis of
       incubation. This was performed applying Kaplan-Meier non-parametric
       survival analysis, and fitting to incubation data three probability
       density functions, representing three different situations with respect
       to the hazard of developing AIDS following seroconversion (namely
       Weibull (WE), generalized exponential (GE) and log-logistic (LL)). The
       cumulative incidence over an 8-year period ranged from 14.9 to 17.8 per
       cent when applying the Kaplan-Meier method, from 14.1 to 17.2 per cent
       when using the WE function, from 14.5 to 17.3 per cent when using the GE
       function and from 14.4 to 17.3 per cent when using the LL function,
       depending on the estimate of seroconversion time used. Similarly, the
       median incubation times ranged from 12.6 to 15.0 years with the WE
       function, from 14.0 to 16.5 years with the GE function, and from 13.4 to
       16.1 years with the LL function. The presence of a bound on the increase
       of the hazard function seems to affect the incubation more strongly than
       the eventual decrease following the attainment of the maximum risk. This
       may be due to the decrease in the hazard beginning when most of the
       seropositive subjects have already developed AIDS.
 DE    Acquired Immunodeficiency Syndrome/EPIDEMIOLOGY/ETIOLOGY/  *IMMUNOLOGY
       Blood Coagulation Factors  Blood Transfusion/ADVERSE EFFECTS  Cohort
       Studies  Hemophilia/COMPLICATIONS/*IMMUNOLOGY/THERAPY  Human  HIV
       Seropositivity/EPIDEMIOLOGY/*IMMUNOLOGY/MORTALITY  HIV-1/*IMMUNOLOGY
       Incidence  Italy/EPIDEMIOLOGY  Likelihood Functions  *Models,
       Statistical  Proportional Hazards Models  Support, Non-U.S. Gov't
       Survival Analysis  Time Factors  JOURNAL ARTICLE

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

