topic Re: Retain statement vs. first.ob in SAS Programming

Retain statement vs. first.ob

sarahsasuser — Wed, 24 Apr 2013 18:17:44 GMT

I have a dataset with multiple observations per patient. All patients need to have a certain number of visits. I want to find the patients that are missing visits. If they have not had that visit, there is no observation for that patient for that visit. How do I find which patients are missing those visits?

Re: Retain statement vs. first.ob

data_null__ — Wed, 24 Apr 2013 18:28:33 GMT

When you say "certain number of visits" do you mean scheduled visit or just any visits as long as the number is sufficient. We like example data too.

Re: Retain statement vs. first.ob

PGStats — Wed, 24 Apr 2013 18:29:46 GMT

Try this :

%let expectedNbVisits=3;

Proc sql;

create table missingVisits as

select patientId, count(visitDate) as nbVisits

from patientData

group by patientId

having count(visitDate) < &expectedNbVisits;

select * from missingVisits;

quit;

Re: Retain statement vs. first.ob

sarahsasuser — Wed, 24 Apr 2013 18:35:12 GMT

The study requires 10 visits, but we haven't reached the date where any patient would have all 10 visits yet. Currently we are at visit 4. So I want to see how many patients are missing any of the first 4 visits. I've created a calculated variable that is the visit due date, as I'd also like to see who had a late visit.

Patient ID Visit# Visit date Visit due date

123 1 1/1/13 1/1/13

123 2 2/1/13 2/1/13

123 3 3/1/13 3/1/13

124 1 2/22/13 2/12/13

124 3 4/24/13 2/24/13

125 1 1/1/13 1/1/13

125 2 2/1/13 2/1/13

125 4 4/15/13 4/1/13

Re: Retain statement vs. first.ob

data_null__ — Wed, 24 Apr 2013 19:46:57 GMT

I might do something like this. Build a visit schedule for each subject and join it with the actual data then you can count the holes and see if the schedule visit times are close.

data visit;
   infile cards dsd; 
   input patno visit date:mmddyy.; 
   format date date.; 
   cards; 
123,1,1/1/13 
123,2,2/1/13 
123,3,3/1/13 
124,1,2/22/13 
124,3,4/24/13 
125,1,1/1/13 
125,2,2/1/13 
125,4,4/15/13 
;;;;
   run; 
data schedule;
   set visit;
   where visit eq 1; 
   do visit=1 to 4; 
      edate = intnx('MONTH',date,visit-1,'Sameday');
      output; 
      end; 
   format edate date.; 
   drop date;
   run; 
data visit2;
   merge schedule(in=in1) visit(in=in2);
   by patno visit;
   if not in2 then mvisit=1; 
   if not missing(date) then dif = date - edate;
   run; 

Re: Retain statement vs. first.ob

Astounding — Wed, 24 Apr 2013 20:09:50 GMT

Another approach:

data want;

set have;

by patient_id visit;

if first.patient_id then expected_visit=1;

else expected_visit + 1;

if (visit ne expected_visit) or (last.patient_id and visit < 4) ;

run;

This will point out additional problems that might exist in the data, such as a patient having two observations with visit=3.

Good luck.

Re: Retain statement vs. first.ob

PGStats — Wed, 24 Apr 2013 21:13:47 GMT

How about :

data patientData;
informat visitDate visitDueDate mmddyy.;
format visitDate visitDueDate ddmmyy10.;
input PatientID   VisitNo   VisitDate VisitDueDate;
datalines;
123               1          1/1/13    1/1/13
123               2          2/1/13     2/1/13
123               3          3/1/13     3/1/13
124               1           2/22/13   2/12/13
124               3          4/24/13    2/24/13
125               1          1/1/13    1/1/13
125               2          2/1/13     2/1/13
125               4          4/15/13    4/1/13
;

%let totalVisits=10;

data visits; do visitNo=1 to &totalVisits; output; end; run;

proc sql;
create table expandedPatientData as
select P.patientId, V.visitNo,
case
when visitDate is missing then "- "
when visitDate > visitDueDate then put(intck("DAY",visitDueDate, visitDate), 3.)
else " "
end as code length = 3
from
(select distinct PatientId from patientData) as P cross join
visits as V left join
patientData as X on P.patientId=X.patientId and V.visitNo=X.visitNo
order by patientId, visitNo;
quit;

proc transpose data=expandedPatientData out=patientDataList prefix=V;
by patientId;
id visitNo;
var code;
run;

proc print data=patientDataList;
var v1-v&totalVisits;
ID patientId;
run;

Patient
ID V1 V2 V3 V4 V5 V6 V7 V8 V9 V10

          123                        -     -     -     -     -     -      -
          124      10    -     59    -     -     -     -     -     -      -
          125                  -     14    -     -     -     -     -      -

Re: Retain statement vs. first.ob

Ksharp — Thu, 25 Apr 2013 03:16:16 GMT

Or SQL.

proc sql;
 select count(distinct pid) as How_Many
  from (select * from have group by pid having count(distinct pid) lt 4);
quit;

Ksharp