steady state in WinNonlin… [Software]

posted by Helmut Homepage – Vienna, Austria, 2007-04-05 18:40 (5407 d 12:16 ago) – Posting: # 637
Views: 15,429

Dear PKPDPKPD!

» » ...or ask Pharsight's support - and be patient!

» It's true. LinMix is a catastrophy and I am fighting through it. Till now not very succesfull.

Full ACK, and the manual isn't very helpful either.
I guess Pharsight would call it 'steep learning curve' and want you to sign up in one of their courses... ;-)

I'm waiting for a correct implementation of a paired design (e.g., comparing steady state AUC with single dose AUC in the same subjects) since February 25th, 2007... :angry:

» » I know some colleagues are using repeated measures ANOVA; I never could understand why.
» » The outcome is always a yes/no result.
» » What if you get a significant result - would you really throw away the entire study?
» » If you are testing individual subjects, you have the option - providing you have stated such a procedure in the protocol - to exclude only these subjects from the evaluation since they did not reach steady state.

» An interesting approach. Till now (I am pretty fresh) have not seen any protocols with individual assessment of the achievment of steady state. Is it because it is more time consuming???? And what is about multiple comparisons in this case?

It's not time consuming (just ran 24 subjects on a 2x2.8GHz Xeon, 2GB RAM in <10 seconds). Whether you apply model 502 (v5.2) or an ASCII-model of the linear regression, you'll end up with a nice table listing the estimated slopes and their CIs for all subjects.
What do you mean with multiple comparisons?

» Does it mean, that I use 95% CI when I assess steady state by subject and 90% CI when I assess by entire study?

If you mean assessment of steady state I would always use the 95% CI (the 90% CI used in bioequivalence is a rare exception).

You also may opt for a multivariate analysis based on the one-sample Hotelling T2 statistic. Such an approach would not only give you information whether steady state was reached or not, but also when.
Since this test is not included (and I guess will never be) in WinNonlin, you have to go for alternatives.
The cheapest commercial package I know, supporting Hotelling's T2 is NCSS 2007; if you are familiar with the R-language, you may misuse this package under the GPL.

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Helmut Schütz
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