"Looking for the easiest explanation, one can conclude that the Lipitor/Crestor sub-groups could not have a statistically different response function to Apabetalone."

Thanks Iconoclast. Statistical difference vs. Magnitude difference. Although possibly not statistically different, as you say, there could still be an appreciable %RRR magnitude difference between the crestor/apabetalone and lipitor/apabetalone groups, wouldn't you agree? 

BearDownAZ