SAMEDAYEVENT 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 the second part of the transfer or same-day stay had a principal diagnosis of rehabilitation care (CCS 254), medical evaluation (CCS 256), or other types of aftercare (CCS 255 and CCS 257-259), 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).