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NASS Description of Data Elements
The Nationwide Ambulatory Surgery Sample (NASS) is a set of ambulatory surgery databases included in the HCUP family. These databases are created by AHRQ through a Federal-State-Industry partnership.
 
AGE - Age in years at admission
 
Documentation Sections:
General Notes
Uniform Values
General Notes
 

Age in years (AGE) is calculated from the birth date (DOB) and the admission date (ADATE) in the HCUP State databases with the few exceptions listed below. Ages over 89 are aggregated into a single category of 90 years or older in the HCUP nationwide databases starting in data year 2012.

Exceptions for assigning AGE:

  • AGE is set to the supplied age if the age cannot be calculated (ADATE and/or DOB is missing or invalid). Note: If the supplied age is the age at discharge instead of the age at admission, then the supplied age is NOT used.
  • AGE is missing (.) if the age cannot be calculated and the supplied age is missing.
  • AGE is invalid (.A) if
    • it is out of range (AGE NE 0-124) or
    • the age cannot be calculated and the supplied age is nonnumeric.

    An invalid calculated AGE is not replaced by the supplied age.

  • If the data source does not provide the necessary dates to calculate age or the reported age at admission, then beginning in the 1998 data, AGE is not present on the HCUP files. In the 1988-1997 data, AGE is retained on the HCUP files and is set to unavailable from source (.B).
  • AGE is set to inconsistent (.C) if one of the HCUP edit checks is triggered. The age edit checks vary by year.
    • Beginning in the 1998 data, AGE is less than 0 (EAGE02), is greater than 124 (EAGE03), is inconsistent with neonatal diagnoses (EAGE04), or is inconsistent with maternal diagnoses/procedures (EAGE05).
    • In the 1988-1997 data, AGE is inconsistent with AGEDAY (ED021), neonatal diagnoses (ED3nn), maternal diagnoses (ED4nn), or maternal procedures (ED5nn).

When processing the 1996 HCUP data, no adjustment was made for the leap year when age was calculated from date of birth and admission date. This caused infants admitted on the day before their first birthday to have AGE=1 instead of AGE.

 
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Uniform Values
VariableDescriptionValueValue Description
AGEAge in years at admission0-124Age in years
.Missing
.AInvalid
.BUnavailable from source (coded in 1988-1997 data only)
.CInconsistent: beginning with 1998 data, EAGE02, EAGE03, EAGE04, EAGE05; in 1988-1997 data, ED021, ED3nn, ED4nnn, ED5nn
 
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Internet Citation: HCUP NASS Description of Data Elements. Healthcare Cost and Utilization Project (HCUP). August 2019. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/db/vars/age/nassnote.jsp.
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Last modified 8/14/19