Hello
I have a dataset with patients that have different therapies. In the therapies there are multiple medications. It all is in a long format.
It is in this format:
data your_dataset;
input PatientID TherapyID Drug $;
datalines;
1 1 DrugA
1 1 DrugB
1 1 DrugC
1 2 DrugA
1 2 DrugB
1 2 DrugC
1 3 DrugB
1 3 DrugC
1 4 DrugA
1 4 DrugC
1 4 DrugB
1 4 DrugD
2 5 DrugA
2 5 DrugD
2 7 DrugA
2 7 DrugC
3 6 DrugB
3 6 DrugE
;
I would like to identify, which drugs are newly started or finished within a patient, when they have a new therapy. And flag them accordingly.
Solution example:
1 1 DrugA baseline
1 1 DrugB baseline
1 1 DrugC baseline
1 2 DrugA last_time
1 2 DrugB no_change
1 2 DrugC no_change
1 3 DrugB no_change
1 3 DrugC no_change
1 4 DrugA restart
1 4 DrugC no_change
1 4 DrugB no_change
1 4 DrugD new_start
2 5 DrugA baseline
2 5 DrugD last_time
2 7 DrugA no_change
2 7 DrugC new_start
3 6 DrugB baseline
3 6 DrugE baseline
They could also have variables added with a binary value to it.
So far, I have used this code, but there are multiple errors in it.
data drug_changes;
set your_dataset;
by PatientID;
retain PrevPatientID PrevTherapyID FirstTherapyDrugs;
if first.PatientID then do;
PrevPatientID = .;
PrevTherapyID = .;
FirstTherapyDrugs = '';
end;
if PatientID ne PrevPatientID then do;
PrevTherapyID = .;
FirstTherapyDrugs = '';
end;
if TherapyID ne PrevTherapyID then do;
if Drug ne '' then do;
if PrevTherapyID ne . then do;
action = 'Finished';
output;
end;
if TherapyID = 1 then do; /* Check if it's the first therapy */
FirstTherapyDrugs = catx('|', FirstTherapyDrugs, Drug); /* Concatenate drugs */
action = 'First Start';
output;
end;
else do;
action = 'Started';
output;
end;
end;
end;
PrevPatientID = PatientID;
PrevTherapyID = TherapyID;
if last.PatientID then do;
if FirstTherapyDrugs ne '' then do;
do i = 1 to countw(FirstTherapyDrugs, '|');
Drug = scan(FirstTherapyDrugs, i, '|');
action = 'First Start';
output;
end;
end;
if Drug ne '' then do;
if TherapyID = 1 then do; /* Check if it's the first therapy */
FirstTherapyDrugs = catx('|', FirstTherapyDrugs, Drug); /* Concatenate drugs */
action = 'First Start';
output;
end;
else do;
action = 'Started';
output;
end;
end;
end;
drop PrevPatientID PrevTherapyID FirstTherapyDrugs i;
run;
proc print data=drug_changes;
run;
Thank you so much for your help in advance.
Nina
