[R] Odds Ratios in rms package

[Sebastian Pölsterl]

Hi,

I'm using the rms package to do regression analysis using the lrm
function. Retrieving odds ratios is possible using summary.rms. However,
I could not find any information on how exactly the odds ratios for
continuous variables are calculated. It doesn't appear to be the odds
ratio at 1 unit increase, because the output of summary.rms did not
match the coefficient's value.

E.g. print gives me:

                Coef    S.E.   Wald Z Pr(>|Z|)
age              0.1166 0.0289  4.04  <0.0001

whereas summary gives me:

Factor      Low     High     Diff.   Effect S.E. Lower 0.95 Upper 0.95
age         27.0000 37.00000 10.0000  0.78  0.20  0.40        1.17
 Odds Ratio 27.0000 37.00000 10.0000  2.19    NA  1.49        3.22

Does anybody know how these values are obtained, especially in the
presence of interactions?

Best regards,
Sebastian