Only way that i think you will be able to do this is via code. I would use SAS STudio and connect to a cas session.
With datastep syntax below. There might be a different way but here is what i came up with.
cas mySession sessopts=(caslib=casuser timeout=1800 locale="en_US");
libname caspub cas caslib=public; /*libname to the CASLIB that contains data*/
proc sort data=caspub.book1 out=work.book1;
by ID Created_Date Activity_Date;
run;
data work.book1;
set work.book1;
by ID Created_Date Activity_Date;
if first.ID=1 then do; diff=Activity_Date-Created_Date; end;
run;
Hope this helps.
Carmine