Identify specific treatment regimen

[SSK_011523]

Hi everyone, 

I'm interested in keeping only BR-based regimens (1L,2L,3L) and remove other regimens from the dataset.  I'm not interested in distinct observations by patient ID but rather all LOTs for BR-based regimen. I'm not sure how to go about this. Any insight would be helpful.

Following is the data I have - 

ID	DRUG_REGIMEN	LOT	regimen
1	Bortezomib	1L	Chemo monotherapy
1		2L
1		3L
2	Lenalidomide	1L	Chemo monotherapy
2		2L
2		3L
3	Bendamustine + Rituximab	1L	BR-based
3		2L
3		3L
4	Bendamustine + Rituximab	1L	BR-based
4		2L
4		3L
5	Vincristine	1L	Chemo monotherapy
5	Methotrexate	2L	Chemo monotherapy
5	Methotrexate + Vincristine	3L	Other chemotherapy
5	Cyclophosphamide + Doxorubicin + Rituximab + Vincristine	1L	RCHOP/CHOP-based
5		2L
5		3L
6	Bendamustine + Rituximab	1L	BR-based
6		2L
6		3L

Data I want - 

ID	DRUG_REGIMEN	LOT	regimen
3	Bendamustine + Rituximab	1L	BR-based
3		2L
3		3L
4	Bendamustine + Rituximab	1L	BR-based
4		2L
4		3L
6	Bendamustine + Rituximab	1L	BR-based
6		2L
6		3L

[mkeintz]

In the absence of sample data in the form of a working DATA step, this code is untested, but straightforward:

data want;
  merge have (where=(LOT='1L' and regimen='BR-based') in=include)
        have;
  by id;
  if include=1;
run;

It assumes:

1. Data are sorted by ID.
2. The indicator of a desired ID is to have an observation with LOT='IL' and regiment='BR-bases'.
3. You want the entire collection of obs for such ID's.