REHABtransfer is one of two data elements that identify transfers, same-day stays, and combined transfer records in the NRD. Readmission analyses do not usually allow the hospitalization at the receiving hospital to be counted as a readmission. To eliminate this possibility, pairs of records representing a transfer are collapsed into a single "combined" record in the NRD. Transfer records are defined as having all of the following characteristics:

• Discharge date of the first inpatient stay equaled the admission date of a subsequent inpatient stay.
• The first record had a discharge disposition of transfer to an acute care hospital.
• The second record was from a different hospital and had an admission source indicating a transfer.

Pairs of discharges are classified as a same-day stay if the discharge date for one inpatient stay was the same as the admission date of a second stay for the same patient (same as transfers), but there was no indication of a transfer by the discharge disposition or admission source. Same-day stays may or may not have involved different hospitals. Same-day stays may indicate that a patient was discharged too soon and then needed to be return to the hospital on the same day. However, it was also possible that these were transfer records with an incorrect or missing discharge disposition and admission source.

Records that were part of transfers and same-day stays were combined into a single record. These combined records account for about three percent of records in the NRD and are identified by the data element SAMEDAYEVENT.

If there was an indication of rehabilitation, medical evaluation, or other aftercare within a combined transfer record, the principal diagnosis from the first part of the stay was retained on the combined record and the record was flagged by the data element REHABTRANSFER (value 1). The criteria to identify these records has changed over time:

Beginning data year 2018

An indication of rehabilitation or aftercare is identified based on either of the following:

• Any record but the last record had a discharge disposition of 62 (Discharged/transferred to an Inpatient Rehabilitation Facility [IRF] including Rehabilitation Distinct part units of a hospital) or 90 Discharged/Transferred to an Inpatient Rehabilitation Facility (IRF) including Rehabilitation Distinct Part Units of a Hospital with a Planned Acute Care Hospital Inpatient Readmission (Effective 10/1/13).
• Any record but the first record had default CCSR FAC010, Other aftercare encounter, for the principal diagnosis.

Through data year 2017

An indication of rehabilitation or aftercare was identified if the latter record had any one of the following Clinical Classifications Software (CCS) categories:

• CCS 254: Rehabilitation care; fitting of prostheses; and adjustment of devices
• CCS 255: Administrative/social admission
• CCS 256: Medical examination/evaluation
• CCS 257: Other aftercare
• CCS 258: Other screening for suspected conditions (not mental disorders or infectious disease)
• CCS 259: Residual codes; unclassified.