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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.
 
AGE - Age in years at admission
 
Documentation Sections:
General Notes
Uniform Values
State Specific Notes
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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State Specific Notes

Arkansas

Only the calculated age could be used to assign AGE because Arkansas did not supply age in years.



Arizona

The reported age was not used when AGE could not be calculated because Arizona supplied age at discharge.

Beginning with 2005, source AGE is no longer supplied.



California

In all years, California assigned the date of birth to admission date when the admission date was not reported and the discharge had a principal diagnosis indicating a newborn (defined as DX1 equal to V3x.0x). This caused the calculated age to be 0 days.

Prior to 1995, California reported ages at discharge. Only the calculated age was used to assign AGE.

Beginning in 1995, California reported ages at admission. When AGE could not be calculated from dates, the reported age was assigned.



Colorado

Beginning in data year 2014, the reported age was used to assign AGE. Age could not be calculated because the date of birth (DOB) provided by Colorado does not include the day of birth. Only birth month and year are provided. The day of birth was set to 15 for all records.

Beginning with 1998, the Colorado supplied age at admission was used to assign AGE when the age could not be calculated.

From 1994-1997, Colorado supplied age at admission. For consistency with earlier years of the SASD, however, only the calculated age was used to assign the HCUP variable AGE.

From 1988-1993, Colorado did not supply age at admission. Only the calculated age could be used to assign the HCUP variable age.



Connecticut

Patient age could not be calculated from dates since Connecticut did not report full dates of birth. During HCUP processing, only the reported age could be used to assign AGE.



Florida

Beginning in 2004, Florida provides DOB and ADATE for all discharges.

In 1997, patient age could not be calculated from dates since Florida did not report admission or birth dates. During HCUP processing, the reported age was used to assign AGE. From 1998 to 2001, Florida supplied admission date and date of birth for patients less than 11 years old. For patients over 10 years old, the reported age in years was used to assign AGE. Beginning in 2002, Florida reported age for all discharges, but did not provide admission date and date of birth.



Hawaii

Beginning in 1998, Hawaii provided the date of birth (DOB) with a four-digit year.

In prior years, only a two-digit year was available. To compensate for the two-digit birth year, the birth century was assigned as 1800 if the reported date of birth was after the admission date. Birth century was assigned as 1900 for all other records.



Illinois

Only the calculated age could be used to assign AGE because Illinois did not supply age in years.



Iowa

AGE may differ by one year from the actual age. When only the year of birth is available, Iowa assigns the day and month of birth to '01', which may cause the age calculated from birth date to be one year less than the actual age.



Maine

Starting with 2013 data, the patient age (AGE) is set to 90 for patients age 90 years and older.



Massachusetts

Prior to October 1998, ages greater than 100 years should be interpreted with caution. Age is calculated using the birth and admission date, but only a two-digit year for date of birth (DOB) was provided by the data source. An additional indicator variable provided by the data source, the "Century Birth date," indicates whether the age of the patient was greater or less than 100 years. HCUP experience has shown that this indicator was often not set when it should have been. Thus, if the century indicator specified 1800 or the birth date occurred after the admit date, the century for the date of birth was set to 1800. If the birth date is erroneously after the admit date, this rule causes the age in years (AGE) to be incorrectly greater than 100. If the age does not agree with neonatal or maternal diagnoses and/or procedures, the age is set to inconsistent (.C).

Beginning in October 1998, Massachusetts provides a four-digit birth year. The birth century indicator and the admission date are not used to modify the date of birth.



Michigan

Prior to 2001, age could not be calculated because Michigan did not report admission and birth dates. Beginning with the 2001 data, Michigan provided complete dates and AGE could be calculated.



Nevada

For discharges less than 90 years old, if the age could not be calculated from dates, then the reported age was used to assign AGE. For discharges that are 90 or older, only the calculated age could be used to assign AGE because Nevada sets age in years to 90 for all discharges age 90 and above.



New Jersey

Beginning in 2009 AGE was provided. In 2008, Age was calculated during the HCUP processing.

Prior to 1994, New Jersey reports age as a two-digit code with a maximum of 99 and provides a birth century indicator. Beginning in 1994, New Jersey provides a four-digit birth year. If age could not be calculated (ADATE or DOB missing or invalid) then age was assigned as follows:

Year of Data HCUP processing of AGE
1988-1991 If DOB is greater than ADATE, assign AGE as the reported age plus 100. Otherwise, assign AGE as the reported two-digit age.
1992-1993 If DOB is greater than ADATE, assign AGE as the reported age plus 100. Otherwise, assign AGE as the reported two-digit age and add 100 if the birth century flag indicates that the patient is age 100 or older.
Beginning 1994 Assign AGE as the reported age, if the reported AGE was in the range of 1-124 years. Otherwise, assign AGE as invalid (.A).


New York

Beginning with the 2008 data, the HCUP data element AGE is missing (.) for AIDS/HIV patients. New York identifies AIDS/HIV records by ICD-9-CM diagnosis code, DRG, or MS-DRG:

  • An admitting, principal or any secondary diagnosis of "042", "043", "044", "7958", "27910", "27919", "2793", "1363", "79571", "07951", "07952", "07953", "V017" or "V08".
  • A DRG of 488 through 490 (prior to October 2007) or MS-DRG of 700 through 716 (beginning in October 2007).

Please note that the admitting diagnosis is not retained in the HCUP databases prior to 2012.

In the 1988-1997 HCUP New York databases, AGE could not be calculated because New York did not report full admission and birth dates. During HCUP processing, only the reported age in years could be used to assign AGE.



Oklahoma

Only the supplied age could be used because Oklahoma does not supply date of birth. Oklahoma reports age in years (AGE) as missing for patients with AGE < 1 and does not report age in days (AGEDAY) for patients with AGE >= 1. During HCUP processing AGE was set to 0 for records with a valid value for age in days (AGEDAY).



Oregon

Oregon reports age at discharge. During HCUP processing, reported age was not used when patient age (AGE) could not be calculated from dates. Beginning in 2007, reported age was used if the calculated age was missing.



Pennsylvania

Prior to 1995, only the calculated age could be used to assign AGE because Pennsylvania did not supply age in years. The appropriate edit check for consistency of reported and calculated ages could not be performed.

Beginning in 1995, the source reported age in years. During HCUP processing, AGE was assigned using the reported age if patient age could not be calculated from the dates provided.

Beginning in 2008, only the supplied age in years could be used to assign AGE because Pennsylvania did not provide date of birth.

Birth Century

The availability of birth century information varies across years of data.

  • Prior to 1996, date of birth (DOB) was supplied with a four-digit year.
  • In 1996-1997, only a two-digit year for date of birth (DOB) was provided by the data source.
    • If DOB > admission date (ADATE), the birth century was assigned as 18 (e.g., if ADATE = 01/02/88 and DOB = 01/03/88, then the birth year was set to 1888 and the calculated age was 99).
    • If DOB <= ADATE, the birth century was assigned as 19 (e.g., if ADATE = 01/02/88 and DOB = 01/01/88, then the birth year was set to 1988 and the calculated age in years was 0).
  • Beginning in 1998, the date of birth (DOB) was supplied with a four-digit year.


Pennsylvania

Pennsylvania discharges which are considered as having "sensitive conditions" based on their DRG, diagnoses, and procedures, had AGE set as follows:

If AGE is coded (>= 0), set AGE to the midpoint of 5-year intervals. The age intervals begin with 0-4 and end with 85+. For example,

AGE New Value
0 - 4 2
5 - 9 7
10 - 14 12
15 - 19 17
20 - 24 22
...5 year increment ...midpoint of 5 year interval
85+ 85

The sensitive conditions and the screens for selecting them are listed below. The DRG and ICD-9-CM code screens are separated by "or" operators. The screen for sensitive conditions is updated as appropriate each year. Some out-of-date diagnoses and procedures, marked by "(D)", were dropped from the screen. Other diagnoses and procedures were added; these are marked by "(A)."

  DRG's OR Diagnoses OR Procedures
Abortion 380-381 634-634.92 (D) 69.01, 69.02
635-635.99 (A) 69.09 (AD)
636-636.99 (D) 69.51-69.59
637-637.99 (D) 69.93 (D)
638-638.99 (D) 74.91, 75.0
639-639.99 (D) 96.49 (D)
V61.7  
AIDS/HIV 488-490 042  
043-044.9 (D)
795.71 (A)
795.8 (D)
V08 (A)
V65.44 (A)
Psychiatric 424-432 290-302.9, 306-319 942.1--942.9, 943.1-943.9, 944.1-944.4, 945.1-945.2, 9459
E95.0-E95.90
E98.0-E98.99
V11.0-V11.99 (A)
V790, V798, V799 (A)
Substance Abuse 433-437, 521-523 303-305.93 944.5-944.6, 945.3-945.4, 946.1-946.9
980.0 (A)
V65.42 (A)
V791
Venereal Disease   090.0-099.9  
V027
V028


South Carolina

The calculation of AGE differs across years.


Beginning in 2000


South Carolina reported a four-digit year for date of birth (DOB). No adjustments to birth century were made during HCUP processing.


From 1996 to 1999


Only a two-digit year for date (DOB) was provided by the data source.

  • If DOB > admission date (ADATE), the birth century was assigned as 18 (e.g., if ADATE = 01/02/88 and DOB = 01/03/88, then the birth year was set to 1888 and the calculated age was 99).
  • If DOB <= ADATE, the birth century was assigned as 19 (e.g., if ADATE = 01/02/88 and DOB = 01/01/88, then the birth year was set to 1988 and the calculated age in years was 0).

Using only the admission date to determine births in the 1800s causes no patient ages to be greater than 99 years.


In 1993 and 1995


South Carolina reported a two-digit year for date of birth (DOB). During HCUP processing, the birth century was assigned as 1800 if the reported age was at least 100 or the reported date of birth was after the admission date. Birth century was assigned as 1900 for all other records.


In 1994


South Carolina reported a four-digit year for date of birth (DOB). No adjustments to birth century were made during HCUP processing.



Tennessee

Only the calculated age could be used to assign AGE because Tennessee did not supply age in years.



Texas

Age in years (AGE) was set to the midpoints of age ranges. There are 22 age groups for the general patient population and 5 age groups for the HIV or alcohol/drug use patients. The age groups are shown below:

Texas Restriction on AGE for General Patient Population other than HIV or Drug/Alcohol Use Patients
Age Range New value of AGE
0 0
1-4 2
5-9 7
10-14 12
15-17 16
18-19 19
20-24 22
25-29 27
30-34 32
35-39 37
40-44 42
45-49 47
50-54 52
55-59 57
60-64 62
65-69 67
70-74 72
75-79 77
80-84 82
85-89 87
90 and above 90

Texas Restriction on AGE for HIV or Drug/Alcohol Use Patients
Age Range New value of AGE
0 0
1-17 8
18-44 31
45-64 54
65-74 69
75 and above 75
The HIV or drug/alcohol use patients are identified by any principal or secondary diagnosis code on the record having the first four characters equal to one of the values in the following list: "2910", "2911", "2912", "2913", "2914", "2915", "2918", "2919", "2920", "2921", "2922", "2928", "2929", "3030", "3039", "3040", "3041", "3042", "3043", "3044", "3045", "3046", "3047", "3048", "3049", "3050", "3052", "3053", "3054", "3055", "3056", "3057", "3058", "3059", "7903", "V08" and "042".


Utah

Prior to 2004, the reported age was not used when AGE could not be calculated because Utah supplied age at discharge. Beginning in 2004, Utah supplied the age at admission which was used during HCUP processing.



Virginia

Beginning in 2010, Virginia provided the date of birth (DOB).

Prior to 2010, patient age could not be calculated from dates since Virginia did not report date of birth. During HCUP processing, only the reported age could be used to assign AGE.



Washington

Availability of Reported Age

During HCUP processing of 1988-1992 discharges, the reported age was not used when AGE could not be calculated because Washington reported age at discharge. The appropriate edit check for consistency of reported and calculated ages could not be performed.

Beginning with 1993 discharges, Washington reported age at time of admission, consistent with the HCUP definition of AGE. Therefore, if the patient's age could not be calculated from dates, the reported age was assigned to AGE.


Ages Greater Than 99 Years

For 1988-1992 discharges, due to the coding of date of birth, no patient ages are greater than 99 years. Only a two-digit year for date of birth (DOB) was provided by the data source.

  • If DOB is greater than admission date (ADATE), the birth century was assigned as 18 (e.g., if ADATE = 01/02/88 and DOB = 01/03/88, then the birth year was set to 1888 and the calculated age was 99).
  • If DOB is less than or equal to ADATE, the birth century was assigned as 19 (e.g., if ADATE = 01/02/88 and DOB = 01/01/88, then the birth year was set to 1988 and the calculated age in years was 0).

For 1993-1996 discharges, the birth century was assigned as 1800 if the reported age was at least 100 or the reported date of birth was after the admission date. Birth century was assigned as 1900 for all other record. The age range is not truncated at 99.

In 1997, the reported age was no longer used to indicate ages over 100. This is consistent with the coding of AGE in other states. The coding of AGE in 1997 is the same as specified for 1988-1992.

Beginning in 1998, Washington provided a four-digit birth year with the century. If the reported date of birth was greater than the admission date, then the original date of birth remains unchanged and the age at admission (AGE and AGEDAY) was set to inconsistent (.C).



Wisconsin

Beginning in 2005, Wisconsin no longer codes ages greater than 96 to 96. Prior to 2005, an error during HCUP processing of 1989-1992 discharges caused age in years (AGE) and date of birth (DOB) to be set to missing (.) for all patients born in the year 1900. Beginning with 1993 discharges, AGE and DOB were processed correctly.

From 1989-1994, only the calculated age could be used to assign AGE because Wisconsin did not supply age in years. The appropriate edit check for consistency of reported and calculated ages could not be performed.

For 1995 discharges, the source supplied an age in years which was used if the age could not be calculated from date of birth and admission date.

Beginning in 1996, only the calculated age could be used to assign AGE because Wisconsin had truncated ages over 96 years to age 96.


 
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Internet Citation: HCUP NIS Description of Data Elements. Healthcare Cost and Utilization Project (HCUP). September 2008. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/db/vars/age/nisnote.jsp.
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Last modified 9/17/08