Liang,
As far as I understand it there is no way to use time varying covariates and a semi-parametric hazard model in NONMEM. The only way I know how to do this is with a fully parametric hazard. In general I prefer the fully parametric approach because it tells you something about the time course of the underlying hazard. The semi-parametric Cox approach completely ignores the underlying hazard. A trade off for statistical convenience versus loss of biological knowledge.
Nick
> "Zhao, Liang" wrote:
>
> Dear All,
>
> I have the following questions regarding with COX survial model with Time Dependent Covariate that needs your experience and expertise
>
> (1) Even we can do it with S-Plus or SAS, it can not be handled by NONMEM, am I right? If I am wrong, who has started the work?
> (2) How to make predictions with time-variant covariates based on COX model using S-plus or SAS, if not NONMEM?
>
> The question is asked because certain epidemic diseases are season-sensitive and none assumption on base hazard is advantageous over parametric approaches. Thank you in advance!
>
> Liang Zhao
--
Nick Holford, Dept Pharmacology & Clinical Pharmacology
University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand
email:n.holford_at_auckland.ac.nz tel:+64(9)373-7599x86730 fax:373-7556
http://www.health.auckland.ac.nz/pharmacology/staff/nholford/
Received on Tue Jul 03 2007 - 02:06:16 EDT
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