I have a set of data for 2 visits in patients and I would like to see whether there is a effect of a difference of one variable on another. So, lets say, my variables are A, B, age + gender. I want to see the effect of (amount of change in B) on (amount of change in A).
Is it correct if I model this as
A(BL-FU) = B(BL-FU) + A(BL) + B(BL) + age + gender ?
Also age and gender effects both by A and B.
Please advice on the model. Thank you.