RE: [NMusers] duplicate records

Dear Pavel
 
Personally I would tend to keep analytical issues separate from the
modeling, unless you want to incorporate laboratory imprecision and/or
inaccuracy in your pop-pk model.
There should be pre-established rules for defining how replicate assays are
handled in order to generate final analytical results: this, as well as a
robust definition of outliers (viz, when do you allow yourself to reanalyze
samples ?), are fundamental GLP requirements.
For example, assuming that a sample result meets the outlier criteria, keep
the first of two determinations if the reassay differs by less that 15% (or
20% for that matter), or reject the data entirely if the two results differ
by more than the threshold or run a third replicate.
It is generally more convenient to perform the reassay in duplicate so that
you have 3 values to chose from in your decision tree. (ie, often two values
closely match and one does not).
Another set of issues would be a lack of robustness of the analytical method
or unstability of the analyte in the biological matrix on repeated thawing
and freezing.
 
kind regards
Armel
 
 

-----Original Message-----
From: owner-nmusers_at_globomaxnm.com [mailto:owner-nmusers_at_globomaxnm.com] On
Behalf Of nonmem_at_optonline.net
Sent: Tuesday, January 02, 2007 14:55
To: nmusers_at_globomaxnm.com
Subject: [NMusers] duplicate records



Hello PK/PD Team,

We rerun assays and have duplicate PK observations per one blood sample. It
is clear that outliers should be excluded. What do you do when both
measures are similar? Is it OK to keep and analyze both?

Kind regards,

Pavel



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Received on Wed Jan 03 2007 - 03:38:19 EST