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Re: [NMusers] Guidence regarding scm

From: Shankar Lanke <shankarlanke_at_gmail.com>
Date: Thu, 28 May 2015 11:07:30 -0400

Muhammad,

Based on your earlier email, I may suggest you to focus again on your
results. Make sure, your parameter estimates, error estimates, RSE, CV,
OFV, GOF are in accord. rRUN GAM once. When you are perform forward
addition, add one covariate at a time on CL, based on the results add the
covariates combination. Do the same for V1 (most likely wt only), sometimes
you may not get WT too. But when you apply WT as a covariate on CL & Vd you
may get better model. Your data may dictate WT as a covariate on V2.
Bakcward elimination, p<0.001 wthi chi sq 10.83 will be good. Take a look
at Nonlinear Mixed Effects Models:Theory chapter in Bonate's book.(
https://books.google.com/books/about/Pharmacokinetic_Pharmacodynamic_Modeli=
ng.html?id=kfS5oLko95kC&hl=en)
else chapter 5 section 5.7 in Jill Fideler-Kelly's book.

On Thu, May 28, 2015 at 9:49 AM, Muhammad Usman <usman.ips_at_gmail.com> wrote=
:

> Dear NM Users,
>
> I have developed a model and want to perform SCM by using CRCL, AGE and W=
T
> as continuous covariates and SEX as categorical covariate on CL, V1 and V=
2.
> Below is my control stream which I wrote for running the model. Can someo=
ne
> guide me is it Ok to use this control stream for performing stepwise
> covariate modelling. If there is mistake (which I hope there is with TVV1=
 =
> THETA(2) * WT and TVV2 = THETA(3) * WT) then how can I resolve this pro=
blem
> because when I omit influence of WT on V1 and V2 in model the results are
> worrisome.
>
> $PROBLEM PK
>
> $INPUT ID TIME DV AMT CMT MDV EVID WT CRCL AGE SEX
>
> $DATA Vanco_016_iv_1.csv IGNORE=_at_
>
> $SUBROUTINES ADVAN3 TRANS4
>
> $PK
>
> TVCL = THETA(1) * (1+THETA(6)*CRCL)
>
> TVV1 = THETA(2) * WT
>
> TVV2 = THETA(3) * WT
>
> TVQ = THETA(4)
>
> CL = TVCL*EXP(ETA(1))
>
> V1 = TVV1
>
> V2 = TVV2
>
> Q = TVQ
>
> S1 = V1
>
> $ERROR
>
> IPRED = F
>
> W=F*THETA(5)
>
> IRES=DV-IPRED
>
> IWRES=IRES/W
>
> Y=F+W*EPS(1) ; Combined residual random error
>
> $THETA
>
> (0,0.5,7) ; CL
>
> (0,0.3,0.9) ; V1
>
> 0.732 FIX ; V2
>
> 0.5 ; Q
>
> (0,0.44) ; Proportional error
>
> 0.01 FIX ; Proportional change in CL
>
> $OMEGA
>
> 0.07 ; IIV CL
>
> $SIGMA 1 FIX
>
> $EST SIG=4 MAX=9999 PRINT=5 NOABORT METHOD=1 INTER MSFO=MSFB1
>
> $TABLE ID TIME DV AMT CMT MDV EVID WT CRCL AGE SEX IPRED IWRES ETA1 CWRES
> PRED
>
> NOPRINT ONEHEADER NOAPPEND FILE= mytab3 ;Xpose
>
> $COV
> Best regards
>
> --
> *Muhammad Usman*
> PhD Scholar
> Westfälische Wilhelms-Universität Münster
> Institut für Pharmazeutische und Medizinische Chemie
> - Klinische Pharmazie -
> Corrensstrasse 48
> 48149 Münster
>
> Room No. A120.209
>
> Phone: +49 251/8332171
>
> Mob # +49 176 70962067
>



--
Regards,
Shankar Lanke Ph.D.
Assistant Professor
Department of Pharmaceutical Sciences
College of Pharmacy
The University of Findlay
(O) 419-434-5448
Fax# 419-434-4390

Received on Thu May 28 2015 - 11:07:30 EDT

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