Tommy,
When a variable is defined in NM-TRAN it persists to all subsequent
records in the data set.
You could do something like this:
$ERROR
IF (NEWIND.LE.1) lastA3=0 ; initialize lastA3 for each subject to an
appropriate value
PBDREF_ = -PBINT*EXP(-PBRATE*TIME_) + DEACR*(1-lastA3)
IF (TIME_.NE.0.AND.EVID.NE.1) THEN
lastA3=A(3)
THEN ; special trick is to re-assign lastA3 to itself
lastA3=lastA3
ENDIF
I've not attempted to reproduce the logic of your code example. This is
just to illustrate the principle.
Note that if A(3) is computed with a random variable and if you compute
lastA3 in a conditional block then you need to use a special trick to
save the value. This trick is required because otherwise lastA3 will
have a value of 0 ( the default behaviour for random variables).
Nick
On 23-Oct-15 06:34, Tommy Li wrote:
I am currently developing a nonmem model that attempt to correlate
binary endpoint with binary endpoint from previous time point. This
requires me to save solution to differential at a time record (for
example TIME = 1) so that I can use that value (solution at TIME = 1)
and perform computation at the next TIME record (TIME =2 for example).
Essentially, I need to A(3)t=1 and A(3)t=2 at TIME=2, where A(3)
represent integrated solution of the differential equation specified
in the nonmem model.
In my data, i have current TIME record as well as TIME_, which
represent previous time value. In addition, I have DV and DV_, which
represent current and previous observations. I want to calculate the
effect (PBDREF) at current time as well as effect (PBDREF_) at
previous time. For PBDREF_, i need value A(3) at previous time
(A(3)Previous).
example data structure:
ID,DV,DV_,TIME,TIME_
1,0,0,.,1,0
1,0,0,0,2,1
1,0,0,0,4,2
1,0,0,0,8,4
1,0,0,0,16,8
1,0,0,0,24,16
1,0,0,0,36,24
I came up with the following code but I am not sure if it will work:
I have a PK model and an effect compartment described by DADT(3)
$DES
DADT(1) = -KA * A(1)
DADT(2) = KA * A(1) - CL/V * A(2)
CP = A(2)/V
DADT(3) = KIN * (1 - (CP/(IC50+CP))) - KOUT * A(3)
$ERROR
"USE SIZES, ONLY: NO
"REAL (KIND=DPSIZE) :: A3(NO)
"INTEGER (KING=ISIZE) :: I
..... ## Theta declarations
"IF (NEWIND.NE.2) THEN
"I = 0
"ENDIF
"IF (TIME_.EQ.0.AND.EVID.NE.1) THEN
"I = I+1
"A3(I)=A(3)
"PBDREF = -PBINT*EXP(-PBRATE*TIME) + DEACR*(1-A(3))
"PBDREF_ = PBDREF
"ELSE IF (TIME_.NE.0.AND.EVID.NE.1) THEN
"I = I+1
"A3(I) = A(3)
"PBDREF = -PBINT*EXP(-PBRATE*TIME) + DEACR*(1-A(3))
"PBDREF_ = -PBINT*EXP(-PBRATE*TIME_) + DEACR*(1-A3(I-1))
"ENDIF
.....
What I want to do with the code is to save the values of A(3) in an
array (A3). By saving the values of A(3) in order and using the
indexing variable I, I would be able to recall previous value of A(3)
from A3 by doing: A3(I-1). The first conditional statements is to test
if the current time point is the first record of an individual. In
that case, the indexing variable I is reset. Second conditional
statement is to test the case where previous time is 0 and there is no
observation at time 0. In that case, PBDREF and PBDREF_ will be both
be current value. In the last conditional statement, PBDREF is
assigned value based on A(3)'s current value while PBDREF is assigned
value based on A(3)'s previous value, extracted from the array A3.
What I am not sure is whether the declared variable (A3 and I) will
stick around, since it appears to me that these two variable is
redeclared as nonmem move through data record. In that case,
redeclaring those variable would likely erase the values stored in
them. I tried to only declaring (A3 and I) when nonmem is at the first
record of an individual by moving the declaration under the first
conditional statement. However, fortran doesn't seem to allow that.
This there a way to declare persistent variables such that my code
would work as intended?
Thank you
Tommy Li
--
Nick Holford, Professor Clinical Pharmacology
Dept Pharmacology & Clinical Pharmacology, Bldg 503 Room 302A
University of Auckland,85 Park Rd,Private Bag 92019,Auckland,New Zealand
office:+64(9)923-6730 mobile:NZ+64(21)46 23 53
email: [email protected]
http://holford.fmhs.auckland.ac.nz/
Holford SD, Allegaert K, Anderson BJ, Kukanich B, Sousa AB, Steinman A, Pypendop,
B., Mehvar, R., Giorgi, M., Holford,N.H.G. Parent-metabolite pharmacokinetic models
- tests of assumptions and predictions. Journal of Pharmacology & Clinical
Toxicology. 2014;2(2):1023-34.
Holford N. Clinical pharmacology = disease progression + drug action. Br J Clin
Pharmacol. 2015;79(1):18-27.
