RE: [NMusers] Minimum patients number...

Mats,
  The "rules of thumb" are indeed empiric observations from one
variable. But, if you have two dependent variables, you have twice the
data (one time point, two DVs), and twice the parameters. So, I think
the rule may be consistent, but I don't know how valuable it is in the
first place.



Mark Sale MD
Next Level Solutions, LLC
www.NextLevelSolns.com


> -------- Original Message --------
> Subject: RE: [NMusers] Minimum patients number...
> From: "Mats Karlsson" <mats.karlsson_at_farmbio.uu.se>
> Date: Sat, January 27, 2007 11:41 am
> To: "'Ahmed Hawwa'" <ahawwa1_at_yahoo.com>, <nmusers_at_globomaxnm.com>
>
> Hi,
>
> I think that all the rules of thumb that have been mentioned are based on
> the assumption that you have a single observed variable. If you observe
> several, you certainly can expect to estimate more parameterers.
>
> Mvh,
> Mats
>
>
> Mats Karlsson, PhD
> Professor of Pharmacometrics
> Div. of Pharmacokinetics and Drug Therapy
> Dept. of Pharmaceutical Biosciences
> Faculty of Pharmacy
> Uppsala University
> Box 591
> SE-751 24 Uppsala
> Sweden
> phone +46 18 471 4105
> fax +46 18 471 4003
> mats.karlsson_at_farmbio.uu.se
>
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: owner-nmusers_at_globomaxnm.com [mailto:owner-nmusers_at_globomaxnm.com] On
> Behalf Of Ahmed Hawwa
> Sent: Saturday, January 27, 2007 02:10
> To: nmusers_at_globomaxnm.com
> Subject: RE: [NMusers] Minimum patients number...
>
> Hi all,
>
> Thank you all indeed for the valuable commenets. I
> have actually 19 patients only and I need to look into
> the PK parameters of two metabolites.
>
> Minimum 10 patients per eta would mean 50-60 patients.
> I'm sure this number would give optimal results but as
> a matter of fact I don't think I would be able to
> reach it.
>
> > I would suggest that you assess each case on its
> > merits and determine the
> > effectiveness of any proposed design using either
> > simulation linked with
> > estimation (which is tedious, slow, not optimal but
> > often effective)
>
> Regarding using simultation do you mean to put certain
> values of thetas and then run a simulation and compare
> results with the actual concentrations or did I miss
> the point?
>
> > or an
> > information theoretic technique (such as optimal
> > design).
> > The optimal design software WinPOPT
> > (www.winpopt.com), which is freely
> > available, allows you to rapidly assess the
> > effectiveness of various designs
> > as well as optimize a design within your specific
> > study constraints (e.g.
> > clinic visit times etc).
>
> I think one of my study constrains is clinic visit
> times since patients taking our drug are actually
> outpatients and we are able to collect one sample only
> at each clinic visit. would this software be of any
> help??
>
> Looking to hear from you soon.
>
> Regards,
> ahawwa
>
>
>
>
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Received on Sat Jan 27 2007 - 14:49:56 EST