Bioequivalence and Bioavailability Forum

Hi John,

I'll let the stats gurus answer the second point and will focus on the first one.

❝ 1) How should concentration data be reported in terms of the # of signficant digits or decimal places? Which is the proper way?

Scientifically, having a fixed number of significant digit makes sense. I was taught at university that you can't report more significant digits than the figures that you used for your calculations. It makes no sense to report 100.203 if you took a sample of 10.1 mg of reference substance to prepare the stock solutions. Not even to mention your 5, 10 or 15 % CV and accuracy.

If you have a fixed number of decimals: considering the wide range of the calibration curve, you may get 3 significant digits at the LLOQ and 5 or 6 at the ULOQ. At the highest concentration levels your decimals will be nothing more than random numbers.

❝ I mean what if the 90% ratio is 86.55 - 125.05 and the upper end would have passed if the lab uses 3 decimal places instead of 3 significant figures for data presentation? I think they should report the values in 3 decimal places.

I would report the concentrations with 3 significant digits (or more probably 4, actually) but I would calculate AUC with non-rounded concentrations. You can put a note in the report explaining that the concentrations in the tables are rounded but that PK parameters were calculated with full precision to avoid questions from reviewers.