Re: Time-varing covariate
Hi, Sebastien, Bill, Nick, Leonid, Mats and Hans:
Thank you all very much for the suggestions and nice discussions. I enjoyed
to learn from this thread and I am very clear how this should be handled
now. I believe this thread also provided a nice record for other new folks
like me to learn from.
Thanks a lot.
Best regards,
Siwei
Quoted reply history
On Fri, Aug 23, 2013 at 1:10 PM, Nick Holford <[email protected]>wrote:
> Siwei,
>
> I don't know why you think this complicated. Suppose you have age (AGE) as
> a covariate. This must of course be a time varying covariate if it is
> intended to be the current age. And you might have weight (WT) or
> creatinine clearance (CLCR) as covariates which typically change with time.
> So just code the $INPUT data items and use them as you wish e.g.
>
> $INPUT ID TIME AGE WT CLCR etc
> ...
>
> $PK
> ; CL=(CLnon-renal*f(age) + CLrenal*f(renal_function)) * allometric WT
> CL=(THETA(1)*EXP(THETA(2)*(**AGE-40)) + THETA(3)*CLCR/100)*(WT/70)**0.**75
>
> EVID=4 has nothing to do with using time varying covariates.
>
> Perhaps you could explain more clearly what your problem is and why you
> think it is complicated to use time varying covariates?
>
> Best wishes,
>
> Nick
>
>
> On 23/08/2013 6:00 p.m., siwei Dai wrote:
>
>> Hi, Dear NMusers:
>> I want to add a time-varing covariate in my model. For example, blood
>> pressure or blood flow as covariates. But I am not sure how to do it. I see
>> some earlier threads to discuss it but they all use complicated methods.
>> I am wondering if there are any new way to do it in NM 7.2? I see in the
>> user guide that EVID=4 can indicate physiological change. Is this what I
>> should use?
>> Thank you very much for any suggestions.
>> Best regards,
>> Siwei
>>
>
> --
> Nick Holford, Professor Clinical Pharmacology
> Dept Pharmacology & Clinical Pharmacology, Bldg 503 Room 302A
> University of Auckland,85 Park Rd,Private Bag 92019,Auckland,New Zealand
> office:+64(9)923-6730 mobile:NZ +64(21)46 23 53 FR +33(7)85 36 84 99
> email: [email protected]
> http://holford.fmhs.auckland.ac.nz/
>
> Holford NHG. Disease progression and neuroscience. Journal of
> Pharmacokinetics and Pharmacodynamics. 2013;40:369-76
> http://link.springer.com/article/10.1007/s10928-013-9316-2
> Holford N, Heo Y-A, Anderson B. A pharmacokinetic standard for babies and
> adults. J Pharm Sci. 2013: http://onlinelibrary.wiley.**
> http://onlinelibrary.wiley.com/doi/10.1002/jps.23574/abstract
> Holford N. A time to event tutorial for pharmacometricians. CPT:PSP.
> 2013;2:
> http://www.nature.com/psp/journal/v2/n5/full/psp201318a.html
> Holford NHG. Clinical pharmacology = disease progression + drug action.
> British Journal of Clinical Pharmacology. 2013:
> http://onlinelibrary.wiley.com/doi/10.1111/bcp.12170/abstract
>
>
>