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SUMMARY:Joint modelling of competing risks of drug withdrawal and quality 
 of life in epilepsy trials. - Paula Williamson\, Centre for Medical Statis
 tics and Health Evaluation\, University of Liverpool
DTSTART:20070417T133000Z
DTEND:20070417T143000Z
UID:TALK6349@talks.cam.ac.uk
CONTACT:4904
DESCRIPTION:The International League Against Epilepsy has recommended rete
 ntion time\, defined as the time to withdrawal of the randomised drug or a
 ddition of another\, be one of the primary endpoints for clinical trials o
 f anti-epileptic drugs (AEDs). Patients may decide to withdraw from such t
 reatment because of intolerable side effects or poor seizure control.  Fur
 ther\, quality of life (QoL) is increasingly recognised as an important ou
 tcome in epilepsy and a significant proportion of patients report emotiona
 l and social impairments as a consequence of the AEDs and their epilepsy. 
 There is a concern that these impairments may worsen over time.  However\,
  in the presence of a potentially informative event of AED withdrawal\, mo
 delling longitudinal QoL profiles alone may be misleading. The aim of this
  work is to simultaneously investigate the differential treatment effects 
 on competing risks of drug withdrawal and quality of life in newly-diagnos
 ed patients with epilepsy.\n\nStandard methods for joint modelling of long
 itudinal and survival data have one failure type and an assumption of inde
 pendent censoring. In this study we consider joint modelling of the compet
 ing risks (dependent censoring) of drug withdrawal and the repeated measur
 ements of quality of life. We fit a cause-specific hazards model to allow 
 for competing risks\, with a separate association parameter for each AED w
 ithdrawal reason\, and a combined analysis is undertaken.  We present resu
 lts on the gain from a combined analysis over the approach fitting separat
 e models. \n\nAcknowledgment: This work is funded by MRC Grant G0400615
LOCATION:Large Seminar Room\, 1st Floor\, Institute of Public Health\, Uni
 versity Forvie Site\, Robinson Way\, Cambridge
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