I made a logistic regression model 1 (not fully adjusted) and model 2 (fully adjusted; model 1 + covariate A) with Stata. I am trying to calculate the attenuation percentages between OR.
I used the KHB method to make it correctly but I would want compare my results with a "classic" attenuation percentage (attributable fraction):
1) I don't know if additive scale (OR2-OR1)/(OR1-1)x100 or multiplicative scale [ln(OR2)-ln(OR1)]/[ln(OR1)]x100 is better...
I used the multiplicative scale and the result is 49.9%. To calculate an interval confidence, I made bootstrap with repeats=2000 in model 1 and model 2 (with a same seed) and so I could calculate 2000 attenuation percentages and the mean with 95% IC.
2) Is this method correct?
My IC is : 53.8-55.8 % and my attenuation percentage (49.9) is outside my IC.
3) Must I choose an other method of bootstrap?