Re: Missing value when modeling categorical data
Tianli,
Please look carefully at this:
http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford/teaching/pharmacometrics/_docs/modelling_likelihoods_using_NONMEM_VI.pdf
It shows you how to do time to event models which also include PKPD variables which change as a function of dose and time.
Nick
[email protected] wrote:
> Dear Nick,
>
> I think I didn't make it clear in my first email that my model is a PK-PD linked model, which means, the probability of a certain event is a function of drug exposure which can describe as a function of time and some other parameters like CL, V, etc. But it seems to me that the hazard function only takes time into account. I am not familiar with survival analysis so this might be a very basic question: How can I combine the PK/PD model with the time-to-event model?
>
> Thanks in advance,
> Tianli
>
Quoted reply history
> On Oct 8 2009, Nick Holford wrote:
>
> > Tianli,
> >
> > Your data sounds like it could be described by a survival analysis. A time to event model will give you the survivor function i.e. the prob of not having had the event as a function of time. The event in your case is defined by the 'certain PD score'. The censoring will of course be taken care of by a typical survival analysis.
> >
> > Nick
> >
> > [email protected] wrote:
> >
> > > Dear NMUsers,
> > >
> > > I am modeling ordered-categorical PD data versus time, but since the clinical trial is ongoing, I don't currently have complete data set for each subject. In other words, for some subjects, I have 1 year's PD data, but for some others, I can only collect PD data for 1 month. For the 1 month's case, it is like missing data for the rest of time. But I need to consider time course of the proportion of subjects who got a certain PD score. In my case, if I use the general logistic regression model to fit the relationship between time and proportions of event, would there be any problem? If so, how can I avoid it? Or need I consider censoring like survival analysis?
> > >
> > > Any suggestion would be appreciated very much.
> > >
> > > Thanks in advance,
> > > Tianli
> > > *****************************************************************
> > > Tianli Wang
> > > University of Minnesota
--
Nick Holford, Professor Clinical Pharmacology
Dept Pharmacology & Clinical Pharmacology
University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand
[email protected] tel:+64(9)923-6730 fax:+64(9)373-7090
mobile: +64 21 46 23 53
http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford