I have the following dataset below. I have been able to subset the data
1) have patients (Patient_No) with any prior positive outcome and any subsequent negative outcome,
2) have patients with at least 1 prior positive outcome, at least 1 subsequent negative outcome, at least 90 days between the first low positive or negative outcome and most recent negative outcome, most recent outcome should be negative and there are no subsequent positive outcomes.
Data Diagnose;
Input @1 Patient_No $2.
@3 Date MMDDYY10.
@14 Visit_No $2.
@16 Outcome $12.;
Format Date MMDDYY10.;
Datalines;
1 10/21/2000 1 Negative
1 10/25/2000 2 Positive
1 11/01/2000 3 Negative
1 05/28/2001 4 Negative
2 11/22/2000 1 Positive
2 11/29/2000 2 Positive
2 12/28/2000 3 Positive
2 06/28/2001 4 Low positive
2 10/29/2001 5 Negative
3 12/12/2000 1 Positive
3 12/29/2000 2 Positive
3 02/21/2001 3 Positive
3 07/12/2001 4 Negative
3 08/29/2001 5 Positive
;
run;
I have the following code. However, when the first outcome is negative as in Patient 1, the code fails to meet the rules. Instead of having 3 patients in Subset 1, I end up with 2 patients. Instead of having 2 patients in Subset 2, I end up with 1 because the code does not take into account the possibility of a negative first.
data sub1 sub2;
do until(last.patient_no);
set diagnose; by patient_no;
select (Outcome);
when ("Positive") do;
if missing(firstPos) then firstPos = date;
end;
when ("Negative") do;
if missing(firstNeg) then firstNeg = date;
recentNeg = date;
end;
when("Low positive") do;
if missing(firstLow) then firstLow = date;
end;
otherwise;
end;
end;
/* Subset 1 : any prior positive outcome and any subsequent
negative outcome */
if firstPos < firstNeg
then output sub1;
/* Subset 2 */
if
/* at least 1 prior positive outcome */
not missing(firstPos) and
/* at least 1 subsequent negative outcome */
firstPos < firstNeg and
/* at least 90 days between the first low positive
or negative outcome and most recent negative outcome */
intck("day", min(firstLow, firstNeg), recentNeg) >= 90 and
/* most recent outcome should be negative and there are no
subsequent positive outcomes */
Outcome = "Negative"
then output sub2;
keep patient_No; /* Applies to both output datasets */
run;
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