Bioequivalence trial with clinical endpoint

[MBKo]

The clinical endpoint is the mean percent change from baseline to Wk 12 in inflammatory (and non-inflammatory) lesion counts.  Can someone point me to the SAS 9.4 procedure to generate the confidence interval  for the ratio (Test/Reference) of the mean percent change?

Is it common to need to use the log transformation for percent change in acne lesion counts?  Total sample size will be ~1500 subjects.

Thanks in advance for any assistance.

[koyelghosh]

I would have done it like this.

Generated a column of Ratio (of Test/Reference) and then PROC MEANS with CLM option get the confidence limits.

Since I have not seen the data, I might have severely underplayed the complexity you are facing. If the data is not sensitive you can paste a few rows for us to understAnd the problem better.

As far as log transformation is there, I generally do it if the range of numbers is very large (say from 1 to 1Billion) or very small from (0.000000001 to 1). If you do log transformation the range will come out to be 0 to 9 in the first case and -9 to 0. The benefit is your X and/or Y axis is not stretched so that cognitive load on the brain is less. So it depends, in my opinion, what is your range. As far as Norm for Acne is concerned (for log transformation) Google might know the answer. You just might need to patiently talk to it. Try Pubmed (NCBI) papers. See if there is a precedence.

All the best.

[MBKo]

The subjects in the Test group are independent from those in the Ref group, so cannot create the ratio Test/Ref and then take the mean of the ratios.