Re: [NMusers] Sparse (pediatric) and rich (adult) data

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
dependence of CL on WT (if any is noticeable) for very young kids could
be attributed to maturation and explained by AGE covariate
Leonid

--------------------------------------
Leonid Gibiansky, Ph.D.
President, QuantPharm LLC
web: www.quantpharm.com
e-mail: LGibiansky at quantpharm.com
tel: (301) 767 5566




Chandrasekhar Udata wrote:
> 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
> each data set. Although a two-compartment model best describes the
> combined data, the individual parameter estimates in pediatric
> population are different compared to those obtained using with pediatric
> data alone. Note that the parameter estimates in adults were not
> significantly altered with either combined or adult data alone. Body
> weight is the only covariate included in the model with allometric
> exponents fixed to 0.75 on CL and 1 on V1.
>
> I would like to hear your thoughts on this and any suggestions on how to
> proceed with modeling combined data from pediatric and adult studies.
>
> Regards,
> - Chandra
>
Received on Wed May 28 2008 - 13:47:44 EDT