Table 2 Categories of harm adapted from the National Coordinating Council for Medication Error Reporting and Prevention (NCC MERP) Index
    Category ACircumstances or events that have the capacity to cause error
    Category BAn error that did not reach the patient
    Category CAn error that reached the patient but did not cause harm
    Category DAn error that reached the patient and required monitoring or intervention to confirm that it resulted in no harm to the patient
Categories used for adverse events
    Category ETemporary harm to the patient and required intervention
    Category FTemporary harm to the patient and required initial or prolonged hospitalisation
    Category GPermanent patient harm
    Category HIntervention required to sustain life
    Category IPatient death
  • Note that NCC MERP’s “An error that contributed to or resulted in …” has been deleted in the Institute for Healthcare Improvement’s adaptation of categories E–I, because Trigger Tools are designed to find harm, whether or not the result of an error.