topic Re: Difference between two dates- Length of Stay (days) in SAS Programming

Difference between two dates- Length of Stay (days)

alyxm — Thu, 01 Mar 2018 23:18:12 GMT

Hi there!
Stuck on a problem-- I need to determine the length of stay (in days) between two dates (formatted (mmddyyyy) in my dataset: ex. 01/22/2015). Here's my code:

data dates_again;
set work.import;
admitdate=input(mmddyyyy10.);
releasedate=input(mmddyyyy10.);
LOS=intck('dd', releasedate, admitdate);
put los;
run;

I get an error message for admitdate and releasedate, "Expecting an arithmetic expression":

64 admitdate=input(mmddyyyy10.);

___________

386

65 releasedate=input(mmddyyyy10.);

___________

386

ERROR 386-185: Expecting an arithmetic expression.

Help! Not sure what else to do.

Thank you!

Re: Difference between two dates- Length of Stay (days)

ballardw — Fri, 02 Mar 2018 00:48:29 GMT

admitdate=input(mmddyy10.); [ the format only has 2 ys] to actually input would require either a character variable name

admitdate=input(datechar, mmddyy10.); or a date literal string

admitdate=input('02/15/2018', mmddyy10.);

Since "input" didn't work then SAS is expecting an "arithemetic expression";

Are your variables admitdate and releasedate character or numeric. Please run proc contents on the set an determine which.

It may be that your variable is numeric with an existing SAS format of mmddyy10 and no conversion is needed or desired.

If the variables are indeed character then you would need to use input but the target variable name must be a different variable:

admitdatenum = input(admitdate, mmddyy10.) and similar for the releasedate.

LOS= releasedatenum - admitdatenum +1;

LOS=intck('day', admitdatenum, releasedatenum) +1;

the +1 is to include both ends. If released on the date of admission otherwise you get 0.

Using intck you would get a negative value with the admitdate after releasedate. DD is not a valid interval for intck.

Re: Difference between two dates- Length of Stay (days)

Miracle — Fri, 02 Mar 2018 00:48:45 GMT

Hi please try this

data dates_again;
    set work.import;
    sas_admitdate=input(admitdate,mmddyy10.);
    sas_releasedate=input(releasedate,mmddyy10.);
    LOS=intck('day', sas_releasedate, sas_admitdate);
    put los;
run;

Re: Difference between two dates- Length of Stay (days)

alyxm — Fri, 02 Mar 2018 04:48:55 GMT

This worked! Thanks so much! I also had to add "+1" at the end of the LOS row to include both the actual admission date and the release date.
Thanks again!

Re: Difference between two dates- Length of Stay (days)

alyxm — Fri, 02 Mar 2018 05:06:36 GMT

Thanks for responding! Actually, my variables for admitdate and releasedate are numeric, so I actually did not have to convert to SAS format of mmddyy10. Thanks again!