The study population for this example consists of 257 individuals with Type A or B hemophilia who had been treated at two French hospitals since 1978. These patients were at risk for infection by the human immunodeficiency virus (HIV) through contaminated blood factor received for their treatment. By the time of analysis, 188 patients were found to be infected with the virus, 41 of whom subsequently progressed to the acquired immunodeficiency syndrome (AIDS) or other related clinical symptoms. For reasons of simplicity, we refer to all of these events as AIDS. The primary goal of the analysis was to assess the effects of level of treatment received for hemophilia, and age, on the risk of developing AIDS-related symptoms.
The time scale was obtained by dividing the real time axis into 6-month intervals, with \(T=1\) denoting the time period from January 1, 1978 to June 30, 1978.
data(aidsCohort)a data frame with 257 rows and the following variables
left (lower) limit of interval containing the infection time.
right (upper) limit of interval containing the infection
time. It is equal to NA for those with right-censored
infection time at L.Y.
left (lower) limit of interval containing the time of the
first clinical symptoms. It is equal to NA for those who
were not infected by the end of the study period.
right (upper) limit of interval containing the time of the
first clinical symptoms. It is equal to NA for those who
were not infected by the end of the study period or for those
whose time of the first clinical symptoms is right-censored at
L.Z.
the age covariate which is equal to 1 if the estimated age at time infection is \(<20\) years, and 2 otherwise.
treatment group. It is 0 for lightly treated group and 1 for heavily treated group.
factor variable created from age.
factor variable created from group.
data("aidsCohort", package="icensBKL")
summary(aidsCohort)
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