Modèles de mélange en analyse de survie en présence de données groupées : application à la tremblante du mouton

Abstract : Although they are of major interest in the understanding of the classical scrapie dynamic in infected flocks, the factors influencing the contamination by the infectious agent and incubation period remain poorly know. The absence of antemortem diagnostic tools and the confounding effects of long incubation periods and flock management practices yield a partial knowledge of the infectious status of animals. Moreover, we must take into account that only an unknown fraction of animals become infected, even in heavily affected flocks.
To deal with issues, we use a class of particular survival models, which take account for the presence of long term survivors. We propose a penalized likelihood approach, allowing for the estimation of a smooth risk function. We also develop some parametric models with shared frailties to deal with the presence of grouped data. These different models are evaluated through simulations studies.
These statistical approaches are then applied to the analysis of real data collected during the following-up of infected flocks in Pyrénées Atlantiques, France. The key influence of the PRP genotype on the contamination risk and incubation periods is confirmed. Our results also suggest that, at the individual level, the infection mainly takes place around birth. Finally, the strong heterogeneity in the contamination risk and incubation periods observed between flocks could be partially explained by their PRP genetic structure and the number of incubating animals.
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Submitted on : Tuesday, December 11, 2007 - 9:44:52 AM
Last modification on : Wednesday, November 29, 2017 - 2:54:57 PM
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Fabien Corbière. Modèles de mélange en analyse de survie en présence de données groupées : application à la tremblante du mouton. Sciences du Vivant [q-bio]. Université Victor Segalen - Bordeaux II, 2007. Français. ⟨tel-00195495⟩

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