Download 09-44

J Rogers, JL Hutton and K Hemming

Joint Modelling of Event Counts and Survival Times

Date: October 2009

Abstract: We consider the analysis of data from the MRC Multicentre Trial for Early Epilepsy and Single Seizures (MESS), which was undertaken to assess the di®erences between two policies: immediate, or deferred treatment in patients with single seizures or early epilepsy. In studies of recurrent events, like epileptic seizures, there is typically lots of information about individuals' seizure patterns over a period of time, which is often not fully utilised in analysis. We develop methodology that allows pre-randomisation seizure counts and multiple post-randomisation survival times to be jointly modelled, assuming that both these outcomes are predicted by (unobserved) seizure rates. The joint model was found to be superior to standard survival methods, although interesting characteristics within the data, not present in the model were also highlighted. We consider modifications to the joint model to accommodate these properties.

Keywords: Epilepsy; Event rate; Recurrent events; Survival analysis