Re: Time-varing covariate
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
Quoted reply history
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
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Holford NHG. Clinical pharmacology = disease progression + drug action. British
Journal of Clinical Pharmacology. 2013:
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