Covariate analysis
From: "Agoram, Balaji"
Subject: [NMusers] Covariate analysis
Date:Fri, 25 Apr 2003 16:20:50 -0700
I have a novice question on how to select covariates during a popPKPD
analysis using NONMEM.
Specifically I am interested in the following scenarios:
1. While using an indirect response model (stimulation of generation of
response) and the case where my Kin and Kout are known apriori and therefore
are not fitted, I find that my fitted EC50s are correlated with Kins. Can I
use Kin as a covariate for EC50?
2. Same as (1), but in this case, I am fitting Kin also.
3. For this drug, the CL decreases with each dose. Can I use the total dose
administered as a covariate for the CL?
In general, what rules do you all follow to select covariates. Feel free to
point out any valuable references regarding this subject.
Regards,
Balaji Agoram
Research Scientist I, PKDM
Phone 805 447 4035
Fax 805 375 6416