[NMusers] IIV on res error

From: Y.A. Bijleveld <y.a.bijleveld_at_amc.uva.nl>
Date: Fri, 16 Jan 2015 14:09:27 +0000

Dear all,

I am modeling multi-center log-transformed neonatal data and have construct=
ed a 2-compartment model with ETA’s on Cl, V1 and V2. However, when intro=
ducing interindividual variability on the residual error the MOFV drops >15=
0 points, while previously significant relationships between clearance and =
covariates disappear. I find it strange that the introduction of the IIV ha=
s such an impact and don't fully understand. I have already checked the dat=
a for (extreme) outliers.

Can anyone shed some light?

Thank you so much.

Yuma Bijleveld.

$PK
F1=(BIO1**FDS12) * (BIO2**FDS34)
TVV1=THETA(1)*(WT/70000)
V1=TVV1*EXP(ETA(1))
TVCL=THETA(2)*(WT/70000)**0.75*(GA/281)**THETA(6)
CL=TVCL*EXP(ETA(2))
TVQ=THETA(4)*(WT/70000)**0.75
Q=TVQ
TVV2=THETA(5)*(WT/70000)
V2=TVV2*EXP(ETA(3))
S1=V1

$ERROR
IPRED=LOG(0.0001)
IF(F.GT.0)IPRED=LOG(F)
IRES = DV-IPRED
W=1
IF(F.GT.0)W = SQRT(THETA(3)**2)
IWRES = IRES/W
Y = IPRED+W*EPS(1)*EXP(ETA(4))
$THETA
(0, 75.7) ;1 V1
(0, 2.09) ;2 CL
(0, 0.376) ;3 add
(0, 3) ;4 Q
(0, 31.8) ;5 V2
(0, 3.3) ;6 GA
$OMEGA BLOCK(2)
0.167 ;1 V1
0.0824 0.12 ;2 Cl
$OMEGA
0.1 ;3 V2
$OMEGA
0.1 ;4 RES
$SIGMA
1 FIX

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Received on Fri Jan 16 2015 - 09:09:27 EST

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