Central Distributor SEDD: Description of Data Elements

ZIP_S - Synthetic patient zip code

Documentation Sections:

General Notes

Uniform Values

State Specific Notes

General Notes

ZIP_S contains a fixed-key (one-to-one) encryption of the patient's residential zip code (ZIP). To prevent inadvertent or intentional identification of specific patients based on the patient's residential zip code, the last 2 digits were encrypted. While it is still possible to identify the state of a patient's residence using the first three unencrypted zip code digits, ZIP_S does not allow placement of a specific patient within a narrower, zip code-based geography. If the zip code in the HCUP outpatient surgery databases and the inpatient databases are the same, the synthetic identifier, ZIP_S is the same. Users of the encrypted zip code data element are strictly forbidden to identify the actual zip code associated with the encrypted zip code. The encrypted zip code (ZIP_S) contains the following special values: Canadian, Mexican, and other or unspecified foreign zip codes (ZIP_S = "C", "M", or "F", respectively). Invalid zip codes (ZIP = "A"). In the 1988-1992 HCUP databases, the zip code is validated against a composite list of zip codes valid as of December 1987, 1990, and 1992. Beginning in the 1993 HCUP databases, the zip code is required only to be numeric. Homeless patients. In the 1988-1999 HCUP databases, (ZIP_S = " ") . Beginning in the 2000 HCUP databases, ZIP_S = "H".

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Uniform Values

Variable Description Value Value Description ZIP_S Synthetic patient zip code nnnnn Synthetic zip codes C Canada M Mexico F Other or unspecified foreign H Homeless (beginning with 2000 data) Blank Missing A Invalid B Unavailable from source (coded 1988-1997 data only)

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State Specific Notes

Hawaii Hawaii uses only one category for all foreign zip codes, including Canada and Mexico. These are assigned to the HCUP category for Other/Unspecified Foreign (ZIP_S = "F"). Maine Maine does not separately classify Canadian, Mexican, or other foreign zip codes.

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