How do I definte a new variable? Death within 1 year after chemo therapy

[sasworker16]

hello, 

I am trying to definte a new variable as "Death within 1 year after chemo therapy" using the following dataset...

Both patient_ID 10001 and 10002 has death_dates, but only patient_ID 10001 should be marked dead within 1 year because the death_date falls within 1 year after First_Chemo_Date whereas patient ID 10002 does not.

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Patient_ID      First_Chemo_Date           Death_Date 

10001                  2010-05-01                  2010-08-01

10002                  2010-07-01                  2012-05-01

------------------------------------------------------------------------

using previous help from generous members of this community, I tried the following.

data w.cancer;

set w.cancer;

IF (FIRST_CHEMO_DATE<DEATH_DATE<FIRST_CHEMO_DATE+365) THEN DEATH_WITHIN_1YR_AFTER_CHEMO=1; ELSE IF

DEATH_WITHIN_1YR_AFTER_CHEMO=0;

run;

However, it is not giving me the result that I want...what am I doing wrong here?

Any help or advice will be appreciated so much..,

[Reeza · Accepted solution]

SAS treats dates as numbers so if you subtract the dates that should be the number of days between chemo and death. 

[sasworker16]

I reformatted my dates and it works now. Thank you for your advice!