I have the following medicine dosage for each patient. I would like to set it missing once there is a 2nd treatment. See the new dosage column.
Patient ID | Medicine date | dosage | # of date | Treatment | Treatment date | New Dosage |
1 | 1/13/2014 | 132 | 7 | 132 | ||
1 | 1/14/2014 | 132 | 8 | 132 | ||
1 | 1/15/2014 | 132 | 9 | 132 | ||
1 | 1/16/2014 | 132 | 10 | 132 | ||
1 | 1/17/2014 | 132 | 11 | 132 | ||
1 | 1/18/2014 | 132 | 12 | 132 | ||
1 | 1/19/2014 | 132 | 13 | 132 | ||
1 | 1/20/2014 | 132 | 14 | 132 | ||
1 | 1/21/2014 | 132 | 15 | 132 | ||
1 | 1/22/2014 | 132 | 16 | 132 | ||
1 | 1/23/2014 | 132 | 17 | 132 | ||
1 | 1/24/2014 | 132 | 18 | 132 | ||
1 | 1/25/2014 | 132 | 19 | 132 | ||
1 | 1/26/2014 | 132 | 20 | 132 | ||
1 | 1/27/2014 | 132 | 21 | A | 27-Jan-14 | 132 |
1 | 1/28/2014 | 132 | 22 | . | 132 | |
1 | 1/29/2014 | 132 | 23 | . | 132 | |
1 | 1/30/2014 | 419 | 24 | A | 10-Feb-14 | |
1 | 1/31/2014 | 286 | 25 | . | ||
1 | 2/1/2014 | 286 | 26 | . | ||
1 | 2/2/2014 | 286 | 27 | . | ||
1 | 2/3/2014 | 286 | 28 | . | ||
1 | 2/4/2014 | 286 | 29 | . | ||
1 | 2/5/2014 | 286 | 30 | . | ||
1 | 2/6/2014 | 286 | 31 | . | ||
1 | 2/7/2014 | 286 | 32 | . | ||
1 | 2/8/2014 | 286 | 33 | . | ||
1 | 2/9/2014 | 286 | 34 | . | ||
1 | 2/10/2014 | 421 | 35 |
Assuming your data is sorted as in your example, you could use:
data want;
set have;
by patient_id;
if first.patient_id then n_treatments = 0;
if treatment='A' then n_treatments + 1;
if n_treatments < 2 then new_dosage = dosage;
drop n_treatments;
run;
It isn't clear if the data you show is what you have or what you want. Please clearly indicate what your data looks like Before the manipulation and then After the manipulation.
It also helps if you can provide your example data in the form of a datastep so we can test code. When you paste values we have to write a data step to read the code and may make choices that do not match your data. For example I do not know for sure which, if any, of your varaibles are character or numeric. If I make an assumption of type and write code to handle that but your data differs it is very likely the solution I propose will not work.
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.
Assuming your data is sorted as in your example, you could use:
data want;
set have;
by patient_id;
if first.patient_id then n_treatments = 0;
if treatment='A' then n_treatments + 1;
if n_treatments < 2 then new_dosage = dosage;
drop n_treatments;
run;
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