Admission day of the week (ADAYWK) is calculated from the admission date (ADATE). If ADAYWK cannot be calculated (ADATE is missing or invalid), then:

• ADAYWK is set to the supplied admission day of the week, if available.
• ADAYWK is missing (.) if the supplied admission day of week is missing.
• If ADAYWK is out of range (ADAYWK NE 1-7) or nonnumeric, it is set to invalid (.A).
• In the 1988-1997 HCUP files, if the data source does not provide the admission date or admission day of week, then ADAYWK is set to unavailable from source (.B).

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

Only the calculated admission day of week could be used to assign ADAYWK because Alaska did not report admission day of week.

Only the calculated admission day of week could be used to assign ADAYWK because Arkansas did not report admission day of week.

Connecticut provides a separate data element with the day of the week in which the patient was admitted or treated. For Connecticut, the HCUP variable ADAYWK is assigned using this data element and not from the admission date which only includes month and year.

To ensure the confidentiality of patients, admission day of week, ADAYWK, was set to missing (.) on all Florida discharges starting in 1993.

During 1990-1992 HCUP processing, only the calculated admission day of week could be used to assign ADAYWK because Maryland did not report admission day of week.

Beginning in 1993, Maryland reported admission day of week. During HCUP processing, the reported admission day of week was assigned if ADAYWK could not be calculated from admission date.

Only the calculated admission day of week could be used to assign ADAYWK because Missouri did not report admission day of week.

In the 1988-1997 HCUP New York databases, ADAYWK could not be calculated because New York did not report full admission dates. During HCUP processing, only the reported admission day of the week could be used to assign ADAYWK. Please refer to the notes for AWEEKEND for information on this data element in data years after 1998.

Prior to 1995, Pennsylvania did not report admission day of week. Only the calculated admission day of week could be used to assign ADAYWK.

Beginning in 1995, the data source reported admission day of week. During HCUP processing, ADAYWK was assigned using the reported admission day of week if the day could not be calculated from admission date.

Only the calculated admission day of week could be used to assign ADAYWK because Tennessee did not report admission day of week.