How to derive age variables without the diagnostic variable

[Sammy_G]

FILENAME REFFILE '/home/u63367626/PATIENTS/Patients.xlsx';

PROC IMPORT DATAFILE=REFFILE
DBMS=XLSX
OUT=WORK.patt;
GETNAMES=YES;
RUN;

PROC CONTENTS DATA=WORK.patt;
RUN;


data patt1;
set patt;
format dob1 date9.;

dob=compress(cat(month,'/',day,'/',year));
dob1=input(dob,mmddyy10.);

age = (dob1)/365.;

run;

[ballardw · Accepted solution]

If your Month, Day and Year variables are numeric then use the MDY function to get a SAS date value:

Dob = mdy(month, day, year);

AGE requires a date to report the the age as of.  There is a SAS function YRDIF that takes two dates and will return years and fraction of a year as a decimal value.

Age_today = yrdif(dob, Today() );

Better would be to pick a date for an "age as of" such as this to calculate an age as of the first day of 2023. Any date you use with a literal value is ddMONyyyy in quotes followed by the d which tells SAS that you want the SAS date value.:

Age = yrdif(dob, '01JAN2023'd);

If you do not want the decimal portion then use the Floor function to round down to the integer.

Age_today = floor(yrdif(dob, Today() ));

SAS dates are the number of days since 1 Jan 1960 so dividing by 365 would give you close to the number of years since 1 Jan 1960 but only for those born after that date. Anyone born before that day would have a negative "age".

[Sammy_G]

Thank you very much, you were really helpful.