topic Re: Trying to find difference between first and last date of same subject in SAS Programming

Trying to find difference between first and last date of same subject

stancemcgraw — Fri, 29 Jul 2022 16:39:16 GMT

Hello,

Im trying to generate the difference between the first and last dates that a patient was on a certain medication in hours. These are listed in the same column.

Data have:

studynum med_admin_date

1 10/26/20 8:00

1 10/27/20 3:00

1 10/28/20 8:00

data want:

studynum difference

1 48

Re: Trying to find difference between first and last date of same subject

PaigeMiller — Fri, 29 Jul 2022 16:46:24 GMT

Are these valid numeric SAS date/time values? What is the type of variable MED_ADMIN_DATE (numeric or character) according to PROC CONTENTS? What is the format of variable MED_ADMIN_DATE according to PROC CONTENTS?

If they are valid numeric SAS datetime value, then PROC SUMMARY gets the job done, it finds the difference in seconds, and then you can divide by 3600 to get hours.

proc summary data=have;
     class studynum;
     var MED_ADMIN_DATE;
     output out=want range=/autoname;
run;

data want; 
    set want;
    hours=MED_ADMIN_DATE_range/3600;
run;

Re: Trying to find difference between first and last date of same subject

Kurt_Bremser — Fri, 29 Jul 2022 17:53:15 GMT

proc sql;
create table want as
  select
    studynum,
    (max(med_admin_date) - min(med_admin_date)) / 3600 as difference
  from have
  group by studynum
;
quit;