| #Hospital | Hospital identifier |
| #Site | Location of the hospital |
| Year | Year (most recent year in the SQLape_input.txt file, with at least 10% of records) |
| #Patient | Patient identifier |
| #Case | Index stay identifier |
| DateIndex | Date of index operation (each day = another eligible operation) |
| Age | Age at admission |
| Gender | 1 = male, 2 = female |
| Programmed | 1=planned, 0=unplanned (corresponding to “admission mode” = 1 or 3 in SQLape_input.txt file) |
| #Group-RO | Clinical groups, used to compute expected rates (labels in Excel table) |
| AdmissionDate | Admission date of the index stay (each eligible discharge) |
| DischargeDate | Discharge date of the index stay (each eligible discharge) |
| RO1 | Expected rate (see prediction models for more details, benchmark) |
| RO0 | Observed rate (1 if potentially avoidable reoperation, 0 if not) |
| ReoperationDate | Date of the reoperation |
| RODelay | Reoperation date – previous operation date |
