Exclude patients from a file, based on patid defined in another file

[jspoend]

Hi there, 

I have 2 datafiles. 

Claims_file: all claims during pregnancy of women insured with a certain insurer

pregID date_claim ATC

1 mmddyy xy

1 mmddyy xy

1 mmddyy xy

2 mmddyy xy

2 mmddyy xy

3 mmddyy xy

3 mmddyy xy

3 mmddyy xy

4 mmddyy xy

4 mmddyy xy

abortions_file: IDs of pregnancies which had an abortion shortly before the start of pregnancy

PregID date_abort

1 mmddyy

3 mmddyy

What I need to do is to exclude all pregnancies (so all claims from any pregnancy) from the claims_file, which are listed in the abortion_file. 

I'm not sure how to go about this.

I usually run this code to ONLY include patients defined in another file, but I'm not sure how to change it, in order to EXCLUDE patients defined in another file. 

data claims_no abort;
set claims_file;
if _n_ = 1
then do;
declare hash a (dataset:"abortions_file");
a.definekey("pregID");
a.definedone();
end;
if a.check() = 0;
run;

Many thanks in advance, Julia

[FreelanceReinh · Accepted solution]

Hi @jspoend,

Just insert a "not" (symbol: ~) into the subsetting IF condition:

if a.check() ~= 0;

(You can also use the mnemonic ne instead of ~=.) Nonzero return codes from the CHECK method mean that the key value (here: the pregID value) was not found in the hash object (here: in the abortions_file). Missing return codes cannot occur anyway, so you can even simplify the condition to

if a.check();

This is equivalent to the requirement that the return code is neither zero nor missing.

[jspoend]

Too simple, thank you very much!