Dates manipulation

[mauri0623]

Starting with the dataset below, we need to identify the index encounter, which is the encounter_date closest to the start_date.
Encounter_date may be up to two weeks prior to intake survey date(start_Date) through 1 week after it
We also need to apply a washout period. To qualify as an index encounter, there must be no other encounters within 183 days prior to the 2 week grace period, up to two weeks before the index period.

Person_ID Encoured_Date Start_Date
00006A7087 10/7/2021 4/5/2022
00006A7087 11/5/2021 4/5/2022
00006A7087 11/15/2021 4/5/2022
00006A7087 12/2/2021 4/5/2022
00006A7087 12/14/2021 4/5/2022
00006A7087 12/21/2021 4/5/2022
00006A7087 1/3/2022 4/5/2022
00006A7087 1/18/2022 4/5/2022
00006A7087 1/25/2022 4/5/2022
00006A7087 2/4/2022 4/5/2022
00006A7087 2/8/2022 4/5/2022
00006A7087 2/17/2022 4/5/2022
00006A7087 3/2/2022 4/5/2022
00006A7087 3/8/2022 4/5/2022
00006A7087 3/18/2022 4/5/2022
00006A7087 4/5/2022 4/5/2022
00006A7087 4/12/2022 4/5/2022
0000E20E92 1/28/2022 4/5/2022
0000E20E92 3/22/2022 4/5/2022
0000E20E92 4/5/2022 4/5/2022
0000E20E92 5/3/2022 4/5/2022
0000E20E92 5/17/2022 4/5/2022
0000E20E92 5/31/2022 4/5/2022
0000E20E92 7/15/2022 4/5/2022
0000E20E92 8/9/2022 4/5/2022
0000E20E92 10/19/2022 4/5/2022
0000E20E92 11/30/2022 4/5/2022
I know how to go 1 week forward and two weeks backward using the intnx function. I however don'w know about how to construct the washout period part.

[Oligolas · Accepted solution]

Hi,

try this:

data have;
input Person_ID :$10. Encounter_date :mmddyy10. Start_Date :mmddyy10.;
format Encounter_date  Start_Date is8601da.;
datalines;
00006A7087 10/7/2021 4/5/2022
00006A7087 11/5/2021 4/5/2022
00006A7087 11/15/2021 4/5/2022
00006A7087 12/2/2021 4/5/2022
00006A7087 12/14/2021 4/5/2022
00006A7087 12/21/2021 4/5/2022
00006A7087 1/3/2022 4/5/2022
00006A7087 1/18/2022 4/5/2022
00006A7087 1/25/2022 4/5/2022
00006A7087 2/4/2022 4/5/2022
00006A7087 2/8/2022 4/5/2022
00006A7087 2/17/2022 4/5/2022
00006A7087 3/2/2022 4/5/2022
00006A7087 3/8/2022 4/5/2022
00006A7087 3/18/2022 4/5/2022
00006A7087 4/5/2022 4/5/2022
00006A7087 4/12/2022 4/5/2022
0000E20E92 1/28/2022 4/5/2022
0000E20E92 3/22/2022 4/5/2022
0000E20E92 4/5/2022 4/5/2022
0000E20E92 5/3/2022 4/5/2022
0000E20E92 5/17/2022 4/5/2022
0000E20E92 5/31/2022 4/5/2022
0000E20E92 7/15/2022 4/5/2022
0000E20E92 8/9/2022 4/5/2022
0000E20E92 10/19/2022 4/5/2022
0000E20E92 11/30/2022 4/5/2022
;
run;

PROC SORT; BY Person_ID Start_Date Encounter_date; RUN;

PROC FORMAT;
value yn
low-<0=' '
0='No'
1-high='Yes';
RUN;

DATA want;
   SET have;
   BY Person_ID Start_Date Encounter_date; 

   /*Encounter_date may be up to two weeks prior to intake survey date(start_Date) through 1 week after it*/
   Survey_low=Start_Date-7;
   Survey_high=Start_Date+7;

   valid_encounter=put(ifn(Survey_low<=Encounter_date<=Survey_high,1,0),yn.);
   /*We also need to apply a washout period. To qualify as an index encounter, 
   there must be no other encounters within 183 days prior to the 2 week grace period, up to two weeks before the index period.*/
   grace_low=Start_Date-14-183;
   grace_high=Start_Date+14;

   retain Encounter_started_in_Range 0;
   if first.Person_ID then Encounter_started_in_Range=0;
   Encounter_started_in_Range=Encounter_started_in_Range+ifn(Survey_low<=Encounter_date<=Survey_high,1,0);
   if Encounter_started_in_Range>1 then washout_failed=1;
   format Survey: grace: is8601da. Encounter_started_in_Range washout_failed yn.;
RUN;

[mauri0623]

Thank you. I appreciate your time. Obviously, you are a very versed programmer. If it is OK I would like to contact you about this. I still have other part of this that I also need a little help with. I however do not want to be demanding. Just if you have a few minutes that you can spare. Any day or any time will be fine. Hope you have a blast weekend. Thank you again.