topic Re: Creating a new date when two diseases are first present in SAS Programming

Creating a new date when two diseases are first present

sashelpwanted — Tue, 15 Apr 2014 19:18:15 GMT

If I had a dataset that contained a Diabetes_Date and a Hypertension_date like the following:

ID Diabetes_date Hypertension_date

111 4/5/05 7/10/06

222 3/4/14 9/6/10

I need a new variable date that would list the date at which they had both Diabetes and Hypertension. So for the above example it would be 7/10/06 for 111 and the 222 ID would be 3/4/14. I know I could do a few if statements to accomplish this, but wondering if there are other easy methods.

Thanks so much!

Re: Creating a new date when two diseases are first present

DBailey — Tue, 15 Apr 2014 19:26:58 GMT

Wouldn't it just be max(diabetes_date,hypertension_date)? I think the max function propagates null values.

Re: Creating a new date when two diseases are first present

RichardinOz — Wed, 16 Apr 2014 10:11:44 GMT

No, I do not think max() propagates nulls unless all the parameters are null. In fact I use max(value, 0) to set missing values to zero. You need the N() function as well to count the number of non null values.

If n(Diabetes_date, hypertension_date) = 2

then combined Date = max(diabetes_date,hypertension_date) ;

Richard