Age in months (AGEMONTH) is reported for patients less than 11 years of age. AGEMONTH is calculated from date of birth (DOB) and the admission date (ADATE) with the following exceptions:

• AGEMONTH is set to the supplied age in months if the age cannot be calculated (ADATE and/or DOB is missing or invalid).
• AGEMONTH is missing (.) if the age cannot be calculated and the reported age in months is missing.
• AGEMONTH is missing (.) if the calculated age in years is out of range (AGE NE 0-124).
• AGEMONTH is invalid (.A) if the age in months cannot be calculated and the supplied age in months is nonnumeric. An invalid calculated AGEMONTH is not replaced by the reported age in months.
• AGEMONTH is set to inconsistent (.C) if AGEMONTH is inconsistent with neonatal diagnoses (EAGE04), or is inconsistent with maternal diagnoses/procedures (EAGE05).

Only the calculated age in months could be used to assign AGEMONTH because Alaska did not supply this information.

Prior to 2001, the reported age in months is available only through 2 years of age. AGEMONTH is missing (.) for patients over 2 years old.

Beginning with the 2001 data, Georgia reported age in months through 11 years of age (0-132 months).

Only the calculated age in months could be used to assign AGEMONTH because Indiana did not supply this information.

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

Only the calculated age in months could be used to assign AGEMONTH because Minnesota did not supply this information.

Only the calculated age in months could be used to assign AGEMONTH because Missouri did not supply this information.

Only the calculated age in months could be used to assign AGEMONTH because Nebraska did not supply this information.

Only the calculated age in months could be used to assign AGEMONTH because Nevada did not supply this information.

Only the calculated age in months could be used to assign AGEMONTH because New Hampshire did not supply this information.

Only the calculated age in months could be used to assign AGEMONTH because North Dakota did not supply this information.

Only the calculated age in months could be used to assign AGEMONTH because Ohio did not supply this information.

Patient age in months (AGEMONTH) could not be calculated from dates because Oklahoma did not report date of birth. During HCUP processing, only the reported age in months could be used to assign AGEMONTH.

Only the calculated age in months could be used to assign AGEMONTH because Rhode Island did not supply this information.

Only the calculated age in months could be used to assign AGEMONTH because South Dakota did not supply this information.

Only the calculated age in months could be used to assign AGEMONTH because Vermont did not supply this information.

For 2010, Washington supplied age in months, but it was calculated using discharge date instead of admission date. LOS can be used to adjust the age accordingly.