have a look at rms package. lrm is logistic regression model, and if fit is the name of your output, you'd have something like this:
fit=lrm(disease ~ age + study + rcs(bmi,3), x=T, y=T, data=dataf)
You have to specify x=T, y=T in the model statement. rcs indicates restricted cubic splines with 3 knots.