logistic regression for model prediction

[momolito]

Hello

I am trying to develop a prediction model for oral cancer using logistic regression using the code below. the final model does not include some known risk factors for oral cancer. How can I modify the code below, to force DRKG, SMOKE, and BNUT among the final selected predictors? Thanks

proc logistic data=SETA;
class sex (REF='1') AGE_GROUP (REF='1') BMI_GRP (REF='1') SMOKE (REF='0') DRKG (REF='0') BNUT (REF='0') EXERCISE (REF='0') MAR_STAT (REF='1') INCOME_GROUP (REF='1') FAMHIST (REF='0') RESIDENCE (REF='1') EDUC (REF='1') MOM (REF='1') FA (REF='1');
model Oral(event='1') = Smoke DRKG BNUT AGE_GROUP SEX BMI_GRP EXERCISE MAR_STAT INCOME_GROUP RESIDENCE EDUC MOM FA FAMHIST/ selection=STEPWISE slstay=0.05;
output out=oral_cancer_final p=predicted;
run;

[StatDave · Accepted solution]

Add the INCLUDE=3 option in the MODEL statement. Be sure to keep those three variables as the first ones listed after the equal sign. 

[momolito]

It worked. Thanks alot for the quick help