Hi Serge,
Thank you for your willingness to help, please see the attached link below with my project.
The final model in the workflow has baseline used as a covariate on kin, while the one just before that does not have this.
Baseline=kin/kout , therefore is it acceptable to set baseline as a covariate on kin from a PK and modeling perspective? Does this make sense to do so, clearly as you can see in my model it is significantly lowering the log likelihood (90points).
We have no idea about the baseline effects , no suspicion, we actually assume baseline has no effect. Please also see the covariate search that I did in my first post above (the continuous covariate plots whereby baseline and kin have a strong relationship), after enabling baseline as a covariate on kin, the etas lose the relationship.
We do assume the baseline is at steady state without drug, but the variability in the population is huge. To give you an idea what we are measuring as baseline, it is the lipoprotein concentration in plasma (mg/dL) in healthy subjects from a Phase 1 study prior to study initiation, it is quite variable.
Is Baseline always identified as significant on Kin by the covariate search, or is this just happening for my particular model? Please see the image in my first post.
I will be happy to include baseline on kin as a covariate, especially since it improves model diagnostics and LL, I just want to be able to justify doing so.
Thanks for your expert help. The link to my model is below (last 2 in the workflow).
https://www.dropbox....01.phxproj?dl=0
Edited by csheme, 01 June 2016 - 05:23 AM.