%0 Journal Article %T Between-Subject and Within-Subject Model Mixtures for Classifying HIV Treatment Response %A Cyprien Mbogning %A Kevin Bleakley %A Marc Lavielle %J Progress in Applied Mathematics %D 2012 %I %R 10.3968/j.pam.1925252820120402.s0801 %X We present a method for using longitudinal data to classify individuals into clinically-relevant population subgroups. This is achieved by treating ``subgroup'' as a categorical covariate whose value is unknown for each individual, and predicting its value using mixtures of models that represent ``typical'' longitudinal data from each subgroup. Under a nonlinear mixed effects model framework, two types of model mixtures are presented, both of which have their advantages. Following illustrative simulations, longitudinal viral load data for HIV-positive patients is used to predict whether they are responding -- completely, partially or not at all -- to a new drug treatment. %U http://cscanada.net/index.php/pam/article/view/2922