topic Re: creating a variable using temporal criteria in a long data file in New SAS User

creating a variable using temporal criteria in a long data file

lmyers2 — Wed, 17 Mar 2021 05:57:37 GMT

How would you use the data step to find a specific value after a certain criteria is met. I have a long file that has timestamps that is sorted (sample below). I'm looking to find how many patients get "CPAP" any time after a row of HF. The answer here would be patient 1 and 2 so 2 of the 3 patients.

Patient Tier oxygen Timestamp

1 1 NC Time

1 3 HF Time

1 3 CPAP Time

2 3 HF Time

2 3 CPAP Time

3 1 NC Time

Re: creating a variable using temporal criteria in a long data file

PeterClemmensen — Wed, 17 Mar 2021 06:01:53 GMT

So what does your desired result look like? Do you want all observations for the ID's that satisfy this?

Re: creating a variable using temporal criteria in a long data file

PeterClemmensen — Wed, 17 Mar 2021 06:09:05 GMT

If so then do

data have;
input Patient Tier oxygen $ Timestamp $;
datalines;
1 1 NC   Time
1 3 HF   Time
1 3 CPAP Time
2 3 HF   Time
2 3 CPAP Time
3 1 NC   Time
;

data want(drop = f:) ;
   do until(last.Patient);
      set have;
      by Patient;
      if oxygen = 'HF' then f1 = 1;
      if oxygen = 'CPAP' and f1 then f2 = 1; 
      output;
   end;

   do until (last.Patient);
      set have;
      by Patient;
      if f2 then output;
   end;
run;

Re: creating a variable using temporal criteria in a long data file

Kurt_Bremser — Wed, 17 Mar 2021 16:47:59 GMT

data want;
do until (last.patient);
set have;
by patient;
if oxygen = 'HF' then f1 = 1;
if f1 and oxygen = 'CPAP' then f2 = 1;
end;
if f2;
keep patient;
run;

Re: creating a variable using temporal criteria in a long data file

lmyers2 — Wed, 17 Mar 2021 15:35:31 GMT

Thanks - does this take into account the order? Meaning the do loop will find HF then will continue looking for cpap lower down in a long file that is already sorted by time?

I think this code almost works but I get an error-73-322 “expecting an =“ on last.patient that doesn’t make sense...

Re: creating a variable using temporal criteria in a long data file

Kurt_Bremser — Wed, 17 Mar 2021 16:47:09 GMT

It will process the dataset in the order it is stored. I found a mistake in my code I will correct.
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