LOS and LOS_X are artificially assigned to 0 on all records. California did not provide an admission date, discharge date, or length of stay. During HCUP processing, service date was loaded into the admission date (ADATE) and discharge date (DDATE) so that other variables like age at admission and discharge quarter could be calculated.

Beginning in 2007, the reported length of stay was used when LOS could not be calculated during the HCUP processing.

The supplied length of stay was not used when LOS_X could not be calculated because Colorado coded same-day stays with the value 1. Thus, LOS_X was always calculated using ADATE and DDATE and should be zero for most cases.

Beginning in 2005, Florida provided full admission and discharge dates. LOS_X was calculated based on these dates.

Length of stay was not provided on the source file and could not be calculated because date variables were not available for patients less than 11 years of age.

Beginning in 2004, Florida provided admission date (ADATE) and discharge date (DDATE) the supplied length of stay was used when LOS and LOS_X could not be calculated from the supplied dates.

In 2000-2003, the supplied length of stay was used to assign LOS and LOS_X because Florida did not provide the admission and discharge date necessary for calculating length of stay. The supplied length of stay was coded according to the HCUP standard that assigns a length of stay of zero (0) to same day stays.

In 1997-1999, the coding of LOS and LOS_X is inconsistent with the coding of length of stay in other states. Florida provided the reported length of stay but not the admission and discharge date necessary for calculating LOS_X. Florida codes same-day stays as LOS_X=1; the HCUP standard coding of same-day stays is LOS_X=0. Usually 2% of a states' discharges are same-day stays.

Prior to 1997, the supplied length of stay was not used when length of stay could not be calculated because Florida:

• coded same-day stays with the value 1 and
• subtracted days of absence.

Only the calculated length of stay could be used to assign LOS_X because Indiana codes same day stays with a value of 1.

The reported length of stay was not used when length of stay could not be calculated because Kansas coded same-day stays with a value of 1.

Prior to July 2001, Maryland did not supply length of stay and reported only the date of service. LOS and LOS_X were therefore set to zero. Beginning in July 2001, Maryland provided the "From Date" and "To Date" resulting in calculation of the length of stay.

Beginning in 2006, LOS was calculated during the HCUP data processing.

Beginning with the 2007 data, Missouri supplied admission and discharge dates for calculating LOS for all discharges. The reported length of stay was only used to assign LOS when dates were unavailable. Prior to 2007, the reported length of stay was not used when LOS could not be calculated because Kentucky coded same-day stays with a value of 1. The appropriate edit check for consistency of reported and calculated length of stay could not be performed.

The reported length of stay was not used when LOS_X could not be calculated because Nebraska coded same-day stays with the value 1.

LOS_X has a constant value of '0' (ADATE = DDATE) for all records due to the definition of same-day surgery discharges in the New Jersey data.

The assignment of LOS and LOS_X varies by year in New York:

• In the 1998-2000 data, the length of stay (LOS and LOS_X) was calculated from the admission and discharge dates. Because New York masked the admission and discharge dates on AIDS/HIV* records, LOS and LOS_X was missing (.) on these discharges.



• In the 1988-1997 data, LOS and LOS_X could not be calculated from dates because New York did not report full admission and discharge dates. The reported length of stay provided by New York did not include leave of absence days. To be consistent with the coding of length of stay in other states, the leave of absence days were added back into the reported length of stay before LOS and LOS_X was assigned.

*Beginning with the 2005 New York identifies AIDS/HIV records by ICD-9-CM diagnosis code or 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 or 700 through 716.

*For 1998- 2004 data, New York identifies AIDS/HIV records by ICD-9-CM diagnosis code or DRG:

• An admitting, principal, or secondary diagnosis of "042" "043" "044" "7958" "27910", "27919", "2793", "1363", "79571", "07951", "07952", "07953" or "V08".
• A DRG of 488 "HIV with Extensive Operating Room Procedure", 489 "HIV with Major related condition", or 490 "HIV with or without Other Related Condition".

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

Beginning with the 2007 data, North Carolina supplied admission and discharge dates for calculating LOS for almost all discharges. The reported length of stay was only used to assign LOS when dates were unavailable. Prior to 2007, the reported length of stay was not used when LOS could not be calculated because North Carolina coded same-day stays with a value of 1.

The calculated length of stay was used to assign LOS_X because Utah did not report the length of stay. If either the discharge date or admission date was missing on the source record, then LOS_X is missing (.).

The reported length of stay was not used when LOS_X could not be calculated because Vermont coded same-day stays with the value 1.

Wisconsin did not supply length of stay. The date of principal procedure was used for the admission date and discharge date during HCUP processing, and LOS_X was calculated from these dates. The calculated length of stay for all records is zero.