An indicator of whether the admission day is on the weekend (AWEEKEND) is calculated from the admission date (ADATE). If AWEEKEND cannot be calculated (ADATE is missing or invalid), then

• AWEEKEND is missing (.) if ADATE is missing (.) or
• AWEEKEND is invalid (.A) if ADATE is invalid (.A).

Beginning in the 1998 HCUP files, the data element ADAYWK is replaced by admission weekend (AWEEKEND).

Beginning in 2000, Connecticut provides the necessary information to code AWEEKEND.

Beginning in 1997, the reported admission day of week was used to assign AWEEKEND. In 1997, Florida did not provide admission date.

Beginning in 1998, admission date was provided only for those discharges less than 11 years old.

Beginning in 2004 admission date was provided for all discharges.

From data year 1998 to 2000, there may be an error in AWEEKEND. The data source in Florida has reported that during this time period, the reported value was sometimes incorrect. The data source could not specify the magnitude of the problem.

Prior to 2001, the reported admission day of week was used to assign AWEEKEND. Michigan did not provide admission date. Beginning in 2001, Michigan provided admission date.

The assignment of AWEEKEND varies by year in New York:

• Beginning in 2000 data, AWEEKEND is assigned from the reported admission day of the week if the admission date is missing.
• In the 1998-1999 data purchased from NTIS, AWEEKEND was calculated from the admission date. Because New York masked the admission and discharge dates on AIDS/HIV* records, AWEEKEND was missing (.) on these discharges. An updated version of the 1998-1999 data is available through the HCUP Central Distributor with AWEEKEND coded on the New York AIDS/HIV* records. In the 1998-1999 data purchased from HCUP Central Distributor, AWEEKEND in New York was calculated from the reported admission day of week.

*Beginning with 2005, 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", "V017" or "V08".
• A DRG of 488 through 490 or 700 through 716.

*From 2001 - 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".