NIS Database Documentation - Corrections

Corrections to the Nationwide Inpatient Sample 2019-2021

If you obtained a copy of the 2019 or 2020 NIS prior to December 1, 2022, we recommend using the following information to correct the assignment of the data element PCLASS_ORPROC (indicating at least one operating room procedure is included on the discharge record). The value PCLASS_ORPROC is incorrect on a small number of records: 1.1 percent of the 2019 NIS and 0.3 percent of the 2020 NIS.

Incorrect Assignment of PCLASS_ORPROC

The data element PCLASS_ORPROC should indicate whether there is at least one major diagnostic or therapeutic ICD-10-PCS procedure code on the discharge record. This is determined by the information included in the array of data elements PCLASS1-PCLASS25 for the Procedure Classes Refined for ICD-10-PCS included in the DX_PR_GRPS file. The values for the Procedure Classes are correct, but the corresponding value of PCLASS_ORPROC may be incorrect.

Two Options to Fix the Assignment of PCLASS_ORPROC

One option is to merge the PCLASS1-PCLASS25 data elements from the DX_PR_GRPS file onto the CORE file and correct the assignment of PCLASS_ORPROC using the following code:

SAS Code:
PCLASS_ORPROC = 0;
ARRAY PCLASS (*) PCLASS1-PCLASS25;
DO I = 1 TO 25;
IF PCLASS(I) IN (3,4) THEN PCLASS_ORPROC=1;
END;

SPSS Code:
pclass_orproc = 0.
vector pclass=pclass1 to pclass25.
loop #i=1 to 25.
if pclass(#i) eq 3 or pclass(#i) eq 4 pclass_orproc=1.
end loop.
exe.

Stata Code:
replace PCLASS_ORPROC=0
foreach pclass of varlist pclass1-pclass25 {
replace PCLASS_ORPROC=1 if inlist(`pclass',3,4 )
}

The second option is to download a correction file (provided in CSV format below) that contains a unique record identifier and the corrected values of PCLASS_ORPROC.

Database	Correction File	File Contents	Instructions
2019 NIS	NIS_2019_ORPROC (ZIP file, 19 MB)	Four data elements: HOSP_NIS KEY_NIS PCLASS_ORPROC YEAR	Merge the NIS_2019_ORPROC onto the 2019 NIS Core file by KEY_NIS, replacing the old version of PCLASS_ORPROC with the corrected one from the provided file.
2020 NIS	NIS_2020_ORPROC (ZIP file, 17 MB)	Four data elements: HOSP_NIS KEY_NIS PCLASS_ORPROC YEAR	Merge the NIS_2020_ORPROC onto the 2020 NIS Core file by KEY_NIS, replacing the old version of PCLASS_ORPROC with the corrected one from the provided file.

If you have any questions, please contact the HCUP Central Distributor (866-556-4287 toll-free or HCUP@ahrq.gov).

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NIS Database Documentation - Corrections