Counting Drug Classes

[Deep_Impact]

Hi All, 

I am trying to count (frequency/%) for different/concomitant drug classes by patients who are taking a particular class X. I Need to frequency count only class A,B etc. X class should be 1st used for each patient based on DATE

Patient ID  Date                Drug Class

1                   DateFormat9.        X

1                   DateFormat9.       A

1                  DateFormat9.        B

2                  DateFormat9.         X

2                  DateFormat9.        A

2                  DateFormat9.        B

2                  DateFormat9.        X

Thanks

[ballardw]

Your example shows Patient 2 with 2 "X" values.

You didn't supply anything resembling an actual date so I can't tell if that is an error or if you have two identical dates for patient 2.

Better would be to provide some actual data, a small enough set you can calculate by hand the desired results, for those variables and then show the expected result.

Instructions here: https://communities.sas.com/t5/SAS-Communities-Library/How-to-create-a-data-step-version-of-your-dat... will show how to turn an existing SAS data set into data step code that can be pasted into a forum code box using the {i} icon or attached as text to show exactly what you have and that we can test code against.

[Deep_Impact]

@ballardw : Thank you for responding; 

X is a class of drugs. So Patient 2 indeed got 2 different drugs belonging to class X on 2 different dates. Each patient has been sorted according to drug encounter date - meaning patient gets some drug belonging to X on date 1, gets drug class Y on date 2, and drug class Z on date 3. Patient 2 has drug class X (two different drugs)  given on 2 different dates. In some rare instances, 2 different drugs belonging to drug class X may be given on same date. 

I need to calculate the number and % of drug class Y, Z etc who were given drug class X. I also have a column which gives the first encounter date of drug class X. 

Input Data Set 

Patient_id	Encounter Date	First Encounter of Drug Class X	Drug Class
1	Date 1	Date 1	X
1	Date 2	Date 1	Y
1	Date 3	Date 1	Z
2	Date 4	Date 4	X
2	Date 5	Date 4	O
2	Date 6	Date 4	X