aids: ddI versus ddC in HIV-infected Patients
In JSM: Semiparametric Joint Modeling of Survival and Longitudinal Data

Description Format Source References Examples

A randomized clinical trial in which both survival and longitudinal data were collected to compare the efficacy and safety of two antiretroviral drugs, namely ddI (didanosine) and ddC (zalcitabine), in treating HIV-infected patients intolerant or failing zidovudine (AZT) therapy.

A data frame with 1405 observations on the following 12 variables.

ID: patient ID, there are 467 patients in total.
Time: survival time, i.e. time to death or censoring.
death: death indicator: 0 denotes censoring; 1 denotes death.
obstime: time points at which the longitudinal measurements, i.e. CD4 cell counts, are recorded.
CD4: CD4 cell counts measured at obstime.
drug: drug indicator with two levels: ddI and ddC.
gender: gender indicator with two levels: male and female.
prevDiag: AIDS diagnosis at study entry indicator with two levels: AIDS and noAIDS.
AZT: AZT intolerance/failure indicator with two levels: intolerance and failure.
start: same with obstime, starting time of the interval which contains the time of the CD4 cell count measurement.
stop: ending time of the interval which contains the time of the CD4 cell count measurement.
event: event indicator suggesting whether the event-of-interest, i.e. death, happens in the interval given by start and stop.

Goldman, A., Carlin, B., Crane, L., Launer, C., Korvick, J., Deyton, L. and Abrams, D. (1996) Response of CD4+ and clinical consequences to treatment using ddI or ddC in patients with advanced HIV infection. Journal of Acquired Immune Deficiency Syndromes and Human Retrovirology 11, 161–169.

Guo, X. and Carlin, B. (2004) Separate and joint modeling of longitudinal and event time data using standard computer packages. The American Statistician 58, 16–24.

Xu, C., Baines, P. D. and Wang, J. L. (2014) Standard error estimation using the EM algorithm for the joint modeling of survival and longitudinal data. Biostatistics 15, 731–744

1	head(aids)

Loading required package: nlme
Loading required package: splines
Loading required package: statmod
Loading required package: survival

Attaching package: 'JSM'

The following object is masked from 'package:survival':

    pbc

  ID  Time death obstime       CD4 drug gender prevDiag         AZT start  stop
1  1 16.97     0       0 10.677078  ddC   male     AIDS intolerance     0  6.00
2  1 16.97     0       6  8.426150  ddC   male     AIDS intolerance     6 12.00
3  1 16.97     0      12  9.433981  ddC   male     AIDS intolerance    12 16.97
4  2 19.00     0       0  6.324555  ddI   male   noAIDS intolerance     0  6.00
5  2 19.00     0       6  8.124038  ddI   male   noAIDS intolerance     6 12.00
6  2 19.00     0      12  4.582576  ddI   male   noAIDS intolerance    12 18.00
  event
1     0
2     0
3     0
4     0
5     0
6     0