User Support

Do Your own analysis
Explore Expert Research & Limited Datasets

Central Distributor SEDD: Description of Data Elements

PNUM_R - Person number (re-identified)
Documentation Sections:
General Notes
Uniform Values
State Specific Notes
General Notes

PNUM_R is specific to patients (persons) so that multiple admissions by the same patient can be linked within and across institutions.

Because of a change in the algorithm for creating a person number, patients cannot be tracked from before 2003 to after 2003. In HCUP data prior to 2003, a synthetic person number (PNUM_S), created using fixed-key encryption, was available. Starting in data year 2003, a reidentification number (PNUM_R) was used. PNUM_R includes an arbitrarily chosen, identifying number that is unique to the person identifier provided to HCUP.

PNUM_R should not be used for analyses without first consulting summary statistics on:

  • Frequencies of the number of discharges and the number of different hospitals per nonmissing PNUM_R.
  • State-level counts of the number of unique nonmissing PNUM_Rs, the number of discharges associated with these PNUM_Rs, the ratio of these two numbers (discharges/person), and the number of discharges without a PNUM_R.
Uniform Values
VariableDescriptionValueValue Description
PNUM_RPerson number (re-identified)9(n)Person number
State Specific Notes


Starting in 2008, person identifiers (PNUM and PNUM_R) are no longer available in the Arizona files. Patients cannot be tracked after 2007.

The person identifier (PNUM) may not accurately track patients across hospitals. Arizona accepts social security numbers, health insurance claim numbers, and certificate numbers as person identifiers. No documentation was available about the consistency of coding within and across hospitals.


Beginning in 2010, Iowa provides a patient identification number. Social security number (SSN), birth date, and gender are used to create a patient identifier. A patient identifier is not assigned if any of the three fields are missing or invalid (e.g., the SSN is not nine digits or is filled with a recurring character).

Beginning in 2013, Iowa provides a new unique ID that is develop using probabilistic matching based on name, gender and date of birth.

Beginning 2017, Iowa changed their coding scheme for person numbers. Therefore, they cannot be used to track patients in prior years.

North Carolina

North Carolina provides an encrypted social security number. Reporting of the patient's social security number is optional for hospitals in North Carolina. Beginning in the 2000 data, this data element is frequently missing. During HCUP processing, this identifier is re-encrypted.


Utah supplied source-encrypted social security numbers as person numbers. These identifiers are encrypted again during HCUP processing (PNUM_R). Three-digit codes may indicate:

  • newborns who have not obtained a SSN,
  • patients who have no SSN, and
  • patients who choose not to provide his/her SSN.


Internet Citation: HCUP Central Distributor SEDD Description of Data Elements - All States. Healthcare Cost and Utilization Project (HCUP). September 2008. Agency for Healthcare Research and Quality, Rockville, MD.
Are you having problems viewing or printing pages on this website?
If you have comments, suggestions, and/or questions, please contact
Privacy Notice, Viewers & Players
Last modified 9/11/08