ABSTRACT
FIGURE 5.6: Fitted average longitudinal evolutions and event-free survival probabilities for the three class joint model tted to the AIDS dataset.
The current version of the package (1.4-3) does not automatically exclude missing data, and does not create dummy variables for factors; the user is required to do these operations manually. We observe that for some parameters, such as the slope in the longitudinal part, there seem to be signicant dierences between classes. Though a more useful summary of the tted latent class joint model is given in Figure 5.6 that illustrates the average longitudinal evolutions of the square root CD4 cells count for the three latent classes and the corresponding survival probabilities. It is evident that the model has identied three distinct subpopulations. In particular, one group with relatively high and stable CD4 cell count levels that also enjoys high event-free survival rates, a second group that starts with moderate CD4 cell count levels at baseline and deteriorates rather fast and shows high survival rates up to month 12 and then deteriorates, and a third group that starts with low CD4 cell counts levels also deteriorates in time, though slower than group 2, and exhibits the lowest survival probabilities.
