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NIS Description of Data Elements
The NIS is set of longitudinal hospital inpatient databases included in the HCUP family. These databases are created by AHRQ through a Federal-State-Industry partnership.
NPR - Number of ICD-9-CM procedures on this discharge
Documentation Sections:
General Notes
Uniform Values
State Specific Notes
General Notes

NPR indicates the total number of ICD-9-CM procedures (valid and invalid) coded on the discharge record. In assigning NPR, the first listed procedure is included in the count, even if it is blank, so long as there is an additional procedure present (see table below).

Value Description
0 No procedures are coded on the record.
1 Only the first listed procedure (PR1) is coded. All secondary procedures are blank.
2 One secondary procedure (PR2) is coded. The first listed procedure (PR1) may be coded or blank.
3 The second and third procedures (PR2 and PR3) are coded. The first listed procedure (PR1) may be coded or blank.

For data beginning in the fourth quarter of 2015, the count of procedures is stored in the data element I10_NPR to indicate the implementation of the ICD-10-CM/PCS coding system.

A maximum of 15 procedures have been retained on a NIS inpatient record. States that provide fewer than 15 procedures have had the procedure vector padded with blank values. For example, if a state supplied 5 procedures, PR6 through PR15 are blank (" ") on all records from that state. States that provide more than 15 procedures may have information truncated. If an inpatient record from these states had more than 15 non-missing procedures, procedures in positions 16 and above were not included in the NIS file. If the number of procedures coded on this discharge (NPR) is greater than 15, secondary procedures have been truncated from the record. Refer to the general note for the procedure codes (PRn) for the number of procedures provided in each state.

Since on the NIS the number of procedures coded on the discharge record (NPR) can be greater than the number of procedures available on the inpatient record, caution needs to be taken when using NPR to loop through the procedures. A counter for the loop should not extend past 15. Programming code such as the following example SAS statement is needed to take this into account:

DO I = 1 to MIN(15,NPR);
Followed by code to process all procedures.

Uniform Values
VariableDescriptionValueValue Description
NPRNumber of ICD-9-CM procedures on this discharge0 - nnNumber of procedures
State Specific Notes


For 1995-1996 data only, some discharges have NPR greater than 0, and yet all procedure codes are missing. This is due to constraints of the HCUP processor in handling CPT and HCPCS codes. Pennsylvania reports ICD-9-CM procedure codes on most of their discharges, but some use CPT and HCPCS procedure codes. CPT and HCPCS procedure codes could not be retained in the HCUP data because they are 5 characters and the HCUP procedure fields are 4 characters in length. Discharges with CPT and HCPCS procedure codes were processed by HCUP as follows:

  • PRSYS identifies the procedure coding system as CPT or HCPCS.
  • NPR is the number of non-missing CPT or HCPCS procedure codes supplied by Pennsylvania.
  • The HCUP procedure codes are set to missing (PRn = blank).

In other years, CPT and HCPCS codes are either masked or were handled differently in other years. See the Pennsylvania note on procedures (PRn) for specific details.


Internet Citation: HCUP NIS Description of Data Elements. Healthcare Cost and Utilization Project (HCUP). September 2008. Agency for Healthcare Research and Quality, Rockville, MD.
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Last modified 9/17/08