Date:         Tue, 20 Jul 2010 17:15:13 -0400
Reply-To:     Nat Wooding <nathani@VERIZON.NET>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Nat Wooding <nathani@VERIZON.NET>
Subject:      Re: How to code to calculate continuous 12 month period
In-Reply-To:  <201007202049.o6KICAoR006990@willow.cc.uga.edu>
Content-Type: text/plain; charset="US-ASCII"

Dave

Here is a variation of Chang's code.

Nat Wooding

%let NumMonths = 12; ** this is the number of months in the period that you
are checking for;


Data Dave;
Informat PatientID 8. Begin_Date mmddyy10.;
input PatientID  Begin_Date ;
cards;
1            01/01/2009
1            02/01/2009
1            03/01/2009
1            06/01/2009
1            07/01/2009
1            08/01/2009
1            09/01/2009
1            10/01/2009
1            11/01/2009
1            12/01/2009
1            04/01/2010
2            05/01/2009
2            08/01/2009
2            09/01/2009
2            10/01/2009
2            11/01/2009
2            12/01/2009
2            01/01/2010
2            02/01/2010
2            03/01/2010
2            04/01/2010
2            05/01/2010
2            06/01/2010
2            07/01/2010
;
Data Selected;
     set dave;
         by PatientID;
         Format Begin_Date LastMO mmddyy10.;
         If first.patientid then do;
                  Continuous_Months = 1 ;
                  return;
         end;
         LastMo = Lag( Begin_Date );
         if Intck( 'Month' , LastMO , Begin_Date ) = 1 then
Continuous_Months +1;    else Continuous_Months = 1;

         if last.PatientID and Continuous_Months ge &NumMonths then output ;
     Drop LastMo;

run;


-----Original Message-----
From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of Dave
Brewer
Sent: Tuesday, July 20, 2010 4:49 PM
To: SAS-L@LISTSERV.UGA.EDU
Subject: How to code to calculate continuous 12 month period

Hi All,

I have been trying to come up with code to calculate if a patient has been
enrolled in Medicaid for 12 continuous months, but to no avail.

The data consists of a begin date (SAS date) and patient id. The end date
will always be at the end of that month, so it is not needed.

Data:
Patient ID  Begin_Date
1            01/01/2009
1            02/01/2009
1            03/01/2009
1            06/01/2009
1            07/01/2009
1            08/01/2009
1            09/01/2009
1            10/01/2009
1            11/01/2009
1            12/01/2009
1            04/01/2010
2            05/01/2009
2            08/01/2009
2            09/01/2009
2            10/01/2009
2            11/01/2009
2            12/01/2009
2            01/01/2010
2            02/01/2010
2            03/01/2010
2            04/01/2010
2            05/01/2010
2            06/01/2010
2            07/01/2010

ID 1 would not be selected but ID 2 would. The continuous period does not
have to be within a calendar year and I can have as few as 5 records and
as many as 36 records, but the max number of records could change (up or
down).

I would like the code to be dynamic; in other words, I might need to check
for 24 continuous months the next time.

Thanks for your help.
Dave