Dear Nonmem users,
I am trying to model data from 4 studies. These were multi center studies
conducted at different times. 2 of these 4 studies had a crossover design
with 4 dose levels (occasions). However not all individuals had all dose
levels. Most of the individuals had 3 occasions out of 4 dose levels. 2
studies were a crossover design with IV and SC routes of administration.
I was wondering if I could still estimate the BOV (between occasion
variability) when I was analyzing the complete data simultaneously. I have
previously analyzed data from a single study with BOV (with all individuals
having all occasions) . But I have never done this with data from studies
conducted at different times at different sites with some having more than
one occasion and some just one occasion. If yes, do I just estimate the BOV
in the same way as for a single study in the following way ??
ID Study occ time DV amt rate EVID
1 1 1 0 0 3 1 1
1 1 1 1 5 0 0 0
1 1 2 0 0 3 1 1
1 1 2 1 4.5 0 0 0
1 1 3 0 0 3 1 1
1 1 3 1 5.5 0 0 0
2 2 1 0 0 2 2 1
2 2 1 0 7 0 0 0
3 2 1 0 0 2 2 1
3 2 1 0 7.5 0 0 0
4 3 1 0 0 2 2 1
4 3 1 0 7 0 0 0
OC1=0
IF(OCC.EQ.1) OC1=1
OC2=0
IF(OCC.EQ.2) OC2=1
OC3=0
IF(OCC.EQ.3) OC3=1
OC4=0
IF(OCC.EQ.4) OC4=1
BOV1=ETA(6)*OC1+ETA(8)*OC2+ETA(10)*OC3+ETA(12)*OC4
BOV2=ETA(7)*OC1+ETA(9)*OC2+ETA(11)*OC3+ETA(13)*OC4
CL=TVCL*EXP(ETA(1)+BOV1)
V2=TVV2*EXP(ETA(2)+BOV2)
Any help or suggestions are appreciated
Thanks in advance
--Navin
Between Occasion variability
Thanks for the reply.
If I understand that correctly, it means that I have two different kinds of
occasions.
The first one is different studies where different dose levels are
administered. Same individual receiving different dose levels. (example 4
dose levels hence 4 occasions)
The second type is studies where different routes of administration is used.
(example 2 routes hence 2 occasions)
I would then have in total 6 occasions and the two different omega blocks
for these occasions. Or do I seem to miss the way occasions are defined ??
Thanks again
Quoted reply history
On Nov 12, 2007 12:03 PM, Rocio Lledo <[EMAIL PROTECTED]> wrote:
>
>
> Dear Navin,
>
> You can estimate BOV when not all your individuals have the same
> number of occasions.
> The important point is how you define the occasions, as in your case for a
> crossover study you will probably have similar conditions in
> the 4 studies. So that each OCC should be defined with the same conditions
> in your four studies, for instance: in study one, a new OCC is defined
> every
> time you give a new dose, it should be the same way for study two, and so
> forth. This way the BOV will describe the variability within a subject
> from
> one dose to the other. Similarly you can do this for daily or weekly OCC,
> depending on your study design.
> And the way to handle it is as you did it for a single study.
>
> Best regards,
>
>
> Rocío Lledó, PhD
> Division of Pharmacokinetics and Drug Therapy
> Department of Pharmaceutical Biosciences
> Uppsala University
> Biomedicum, Box 591
> Uppsala, 75124
> Sweden
> Tel (mobile): +46-073-7062271
> Tel (office): +46-018-4714304
>
>
>
--
--Navin