It looks like Datatrak is a clinical trial software provider: http://www.datatrak.com/   Their website does not appear to document any interfaces to other software and in fact offers very little in the way of technical support resources full stop. I suggest you contact them and ask how they interface with other software. Do they have a specification for their API? ... View more

Now that's simple: proc sort data=have; by subject_id test_name start_date; run; data want; set have; by subject_id test_name; if first.test_name then rowid =1; else rowid + 1; /* use of a SUM statement causes automatic retain */ run; ... View more