data need (keep=infection) / view=need; set have ; array inf {*} infection_: ; length infection $12; do I=1 to dim(inf) while (inf{I}^=' '); infection=inf{I}; output; end; run; proc freq data=need; tables infection; run;   This program assumes that if a row has fewer than 3 infections, the non-blank values are the leftmost. ... View more

@jcapua2 wrote: Hello,   data have; patient_num Procedure_Date Organ Multiorgan patient33 1/24/2000 Heart No patient33 5/13/2003 Kidney Yes patient33 5/13/2003 Skin Yes patient34 5/7/2007 Lung No patient34 5/27/2009 Heart No   data want; patient_num Procedure_Date Organ Multiorgan Previous_organ patient33 1/24/2000 Heart No No patient33 5/13/2003 Kidney Yes Yes patient33 5/13/2003 Skin Yes Yes patient34 5/7/2007 Lung No No patient34 5/27/2009 Heart No Yes   I want to create a new variable that flags whether a particular patient has had a previous organ procedure. For example, patient34 has 2 different Procedure_date, with a later Procedure_date that occurred with a different organ, flagging that later row with Previous_organ='Yes' but the prior row (the first Procedure_date) Previous_organ='No.'   Also, for patient33, with 3 Procedure_date, but the last 2 dates occurred on the same date but with different organs. It flags the last 2 dates as Previous_organ='Yes' but the prior row (the first Procedure_date) Previous_organ='No.'   Is there any way to do this in SQL or SAS data step? Look up first and last BY GROUP processing. Most of the questions you've asked can be answered using these techniques in a data step.  ... View more

data have; input patient_num : $10. (Procedure_Date Status_Date) (:mmddyy10.) Status $; format Procedure_Date Status_Date mmddyy10.; datalines; patient33 03/07/2002 02/23/2004 Alive patient33 02/23/2004 10/01/2014 Alive patient50 05/07/2007 12/02/2014 Alive patient50 05/27/2009 10/08/2015 Dead ; data want; call missing(_flag); do _n_=1 by 1 until(last.patient_num); set have; by patient_num Procedure_Date; if _n_=2 then _temp=Procedure_Date; if status='Dead' then _flag=0; end; do _n_=1 by 1 until(last.patient_num); set have; by patient_num Procedure_Date; if _n_=1 and missing(_flag) then Days_Between_Procedure=intck('days',Procedure_Date, _temp); output; end; drop _:; run; ... View more