NCC MERP Index for Categorizing Errors
The National Coordination Council for Medication Errors Reporting and Prevention (NCC MERP) developed a scale to categorize the level of patient harm resulting from medication errors. The NCC MERP Index for Categorizing Errors considers factors such as whether the occurrences had any effect on the patient and, if so, the degree of harm (see Table 1). The scale includes categories for circumstances or occurrences wherein harm did not reach the patient (categories A-D), often referred to as “near misses,” and those wherein the patient was actually harmed (categories E-I). Researchers have modified this scale for use in measuring and distinguishing adverse events of all types, rather than only medication errors.5
Table 1: The National Coordinating Council for Medication Errors Reporting and Prevention Index for Categorizing Errors
Category Description Event
A Circumstances or events occur that have the capacity to cause error.
B An error occurred, but the error did not reach the patient.
C An error occurred that reached the patient, but did not cause patient harm.
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. Harm does not reach patient
Cases in which harm reaches patient
E An error occurred that may have contributed to or resulted in temporary harm to the patient and required intervention.
F An error occurred that may have contributed to or resulted in temporary harm to the patient and required an initial or prolonged hospital stay.
G An error occurred that may have contributed to or resulted in permanent patient harm.
H An error occurred that required intervention necessary to sustain life.
I An error occurred that may have contributed to or resulted in patient death.
Source: NCC MERP Index for Categorizing Errors, Press Release. “Medication Errors Council Revises and Expands Index for Categorizing Errors: Definitions of Medication Errors Broadened,” June 12, 2001.