NONMEM Users Network Archive

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RES and WRES output with Beal's M3 method

From: Sebastien Bihorel <Sebastien.Bihorel>
Date: Wed, 07 Apr 2010 11:31:28 -0400

Dear NONMEM users,

We have noticed some problems with the table outputs of RES and WRES,
when we implemented Beal's M3 method as proposed by Ahn and colleagues
(J Pharmacokinet Pharmacodyn (2008) 35:401421). While RES and WRES are
correctly calculated and reported for patients without BLOQ records,
these metrics are reported as being 0 for patients with at least one
BLOQ sample, even for the records that were not flagged as BLOQ. This
behavior seems to be common to NONMEM 6 and 7.

Does anybody know about an NONMEM option or a workaround that would
allow the user to access to the actual RES and WRES for the non-BLQ records?

Any feedback would be greatly appreciated.

Sebastien Bihorel

PS: this is the $ERROR block code we used for a simple proportional RV model

$ERROR (ONLY OBSERVATIONS)

;Information needed for BLQF and > BLQF samples
LOQ=5
SIG = THETA(3)

DFLG=0 ;create a dose record flag
IF(AMT.NE.0) DFLG=1

IPRED=F+DFLG
W=IPRED

;Computations for samples with DV > LOQ (BLQF=0)
IF (BLQF.LT.0.25) THEN
F_FLAG=0
FFLG=0
IRES=DV-IPRED
IWRES=IRES/W
Y=IPRED+W*SIG*EPS(1) ;NOTE: Prediction is a concentration
ENDIF

;Computations for samples with DV <= LOQ (BLQF=1)
IF (BLQF.GE.0.25) THEN
F_FLAG=1
FFLG=1
DUM=(LOQ-IPRED)/(W*SIG)
IPRED=PHI(DUM)
Y=IPRED ;NOTE: prediction is a *probability*
ENDIF
Received on Wed Apr 07 2010 - 11:31:28 EDT

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