Hi,
I am working on a pop PK model to estimate PK parameters in pediatric and adult
patients. Pediatric study (n=20, age 6 yrs) has fewer samples (3) per subject
whereas the adult study (n=50, median age 20 yrs) has 12 samples per subject. A
two-compartment model best describes the data for
Chandra,
Pediatric data alone may not be able to support (with 3 samples per
patient) a two compartment model. So combined adult/pediatric model is
more appropriate. You may also want to scale peripheral compartment
parameters (Q as CL, V2 as V, K12and K21 as CL/V ~ 1/WT^0.25). Remaining
Chandra,
With such a small sample its hard to learn much about differences
between adults and children. Your principled approach using allometric
scaling is a reasonable way to bridge the gap in recognizing that adults
and children are all the same species (see reference below).
Children
Thank you Nick and Leonid for your comments.
Follow-up question:
I do understand that 3 samples per subject may not support 4 parameters model.
However, historically, the compound showed bi-phasic characteristics (in
adults) and I do like to use the same model in pediatrics. Also, the model
Chandra, Nick et al
It is worth noting that while three samples won't support a 4 parameter
model if all patients contribute these samples at exactly the same time
(i.e. the patients are exchangeable from a design perspective) this is not
necessarily the case if the design is optimized to learn
Steve,
I hope that you do not dispute that in this particular case you need to
use adult data (50 full profiles) rather than discard them and use only
kids data (3 sample per subject, 20 subjects)? While optimal design can
be used to extract more information from the same number of samples,
Leonid
I hope that you do not dispute that in this particular case
you need to use adult data (50 full profiles) rather than
discard them and use only kids data (3 sample per subject, 20
subjects)?
I definitely do not dispute the need to have both adult and paediatric data
in the
Leonid
The original question was whether it is beneficial to add
adult data to the pediatric (in the specific case under
study). Your previous e-mail could be interpreted as the
suggestion that one can estimate model parameters with the
pediatric data alone if the pediatric study design
Steve,
The original question was whether it is beneficial to add adult data to
the pediatric (in the specific case under study). Your previous e-mail
could be interpreted as the suggestion that one can estimate model
parameters with the pediatric data alone if the pediatric study design
is
