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Re: Generating TAD with ADDL dosing format

From: Emmanuel Chigutsa <echigutsa>
Date: Tue, 20 Dec 2016 15:14:06 +0000 (UTC)

Hi Camila,
Alternative (simpler) coding to get TAD would be as follows:
$PK (NONEVENT)IF(AMT.GT.0) TDOS=TIMETAD=TIME-TDOS
The trick here is to add NONEVENT after $PK which tells NONMEM to make=
 calls to $PK even for 'hidden' dose times, such as ADDLs, therefore TDOS i=
s updated appropriately.
Mannie

 
      From: Bill Denney <wdenney
 To: "de Almeida, Camila" <Camila.deAlmeida
omaxnm.com" <nmusers
 Sent: Tuesday, December 20, 2016 7:39 AM
 Subject: Re: [NMusers] Generating TAD with ADDL dosing format
   
 Hi Camila, It sounds like you've got two questions here-- one related to N=
ONMEM and one related to the other program you're using to create your VPC.=
  The NONMEM question appears to be "How do I get TAD in my data witho=
ut changing my dataset?"  The second question appears to be "How to I =
stratify my VPC based on that new TAD variable instead of TIME?" For the se=
cond question, what program are you using for VPC? For the first question, =
others may have a more elegant answer, but I think that you're right: =
 ADDL makes many dose-related events difficult.  The simplest answer i=
s to revise your dataset adding a TAD column.  If you can't do that, t=
hen something like this will work assuming that you only have one dosing re=
cord per subject.  (Note that the code below was typed directly into e=
mail, so it may have typos.)
  ; Set TAD to -1 before any dose record for the subject
  IF (NEWIND.EQ.2) THEN
   DOSETIME = -1
   ADDLREC = 0
   IIREC = 0
 ENDIF
 ; Capture the (most recent) dosing information for this subject
 IF (EVID.EQ.1 .OR. EVID.EQ.4) THEN
   DOSETIME = TIME
   ADDLREC = ADDL
   IIREC = II
 ENDIF
 ; Calculate TAD from the single dose record for a subject in the data set =
assuming
 ; that there is only one dose record per subject or that the dose records =
occur
 ; such that the most recent dose record is the only one important for calc=
ulating
 ; TAD for a subject.  This assumption would not hold if there is a do=
se record
 ; with ADDL that has a dose record for a time in the middle of those ADDL =
doses.
  IF (DOSETIME.LT.0) THEN
   ; This subject has not received a dose yet, set TAD to -1
   TAD = -1
 ELSEIF ((TIME-DOSETIME) .LE. ((ADDLREC+1)*IIREC)) THEN
   ; This subject is in the middle of the ADDL records for this dose,
   ; calculate time since most recent dose.
   TAD = (TIME-DOSETIME) - INT((TIME-DOSETIME)/IIREC)*IIREC
 ELSE
   ; This subject is are after the last ADDL dose, calculate time sinc=
e the final
   ; dose (observed so far).
   TAD = (TIME-DOSETIME) - ((ADDLREC+1)*IIREC)
 ENDIF
 Thanks, Bill
 On 12/20/2016 6:45 AM, de Almeida, Camila wrote:
  
 
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4368767 Hello,   I was wondering if I could get some guidance from t=
his great group. My issue is primarily with some diagnostic analysis, but t=
his is taking me back to an old NONMEM problem.   My aim is to run a =
VPC on a model I implemented, and if possible change the idv to TAD instead=
 of TIME. The reason for that is the VPC graph based on TIME looks dreadful=
 as the data is sparse and from different studies of different lengths. =
  I’m having issues generating the TAD output column from my N=
ONMEM run. I naively assumed I could easily do that, but looking at the NON=
MEM archives it seems this gets tricky when your dosing events are written =
using ADDL. Has anyone ever managed to find a solution for this? And if not=
, is there an alternative way to run the VCP on TAD, do we really need to =
get this column from NONMEM’s output?   Thanks all,   C=
amila de Almeida, PhD PKPD Scientist, Modelling & Simulation, IMED Oncology=
 DMPK _____________________________________________________________________=
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 wdenney

   
 
Received on Tue Dec 20 2016 - 10:14:06 EST

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