NCCMERP index for categorizing medication errors
| Category A | Circumstances or events that have the capacity to cause error |
| Category B | An error occurred but the error did not reach the patient (an “error of omission” does reach the patient) |
| Category C | An error occurred that reached the patient but did not cause patient harm |
| Category D | An error occurred that reached the patient and required monitoring to confirm that it resulted in no harm to the patient and/or required intervention to preclude harm |
| Category E | An error occurred that may have contributed to or resulted in temporary harm to the patient and required intervention |
| Category F | An error occurred that may have contributed to or resulted in temporary harm to the patient and required initial or prolonged hospitalization |
| Category G | An error occurred that may have contributed to or resulted in permanent patient harm |
| Category H | An error occurred that required intervention necessary to sustain life |
| Category I | An error occurred that may have contributed to or resulted in the patient’s death |