Glossary
NCC MERP
NCC MERP publishes the Index for Categorizing Medication Errors, which sorts errors into categories A to I by outcome: A is a circumstance that could cause an error, B a near miss, and E to I harm.
NCC MERP — the National Coordinating Council for Medication Error Reporting and Prevention — publishes the Index for Categorizing Medication Errors, the standard way an error is sorted. The index has nine categories, A to I, and the sort is by outcome, not by who made the mistake or how serious it looked at the time. NCC MERP adopted it in 1996 and amended it in 2022.
The three bands are what most questions turn on. Category A is a circumstance or event that had the capacity to cause an error — nothing has happened yet, and a good catch can keep it there. Category B is an error that occurred but did not reach the patient — a near miss. Categories C and D reach the patient without harm: C needs no intervention, D needs monitoring or an intervention, but neither leaves injury. Categories E through I are harm: E is temporary harm requiring intervention, F temporary harm needing hospitalisation, G permanent harm, H a near-death event requiring intervention to sustain life, and I is death.
The index matters beyond reporting because it is the vocabulary. An error rate that counts B's and C's together with I's says nothing; an intervention log sorted by category is what tells a pharmacy where its process actually fails. NCC MERP also defines the words the bands rest on — harm is an unintended physical injury resulting from or contributed to by medical care, an error is a failure in the treatment process that leads to, or could lead to, harm, and a near miss is an error that did not reach the patient. Category B, in one line, is the definition of a near miss.
Taught in
Related terms
- high-alert medication — A high-alert medication is one that bears a heightened risk of significant harm when it is used in error — insulin, heparin, opioids, concentrated electrolytes. The risk is the harm, not a higher error rate.
- tall man lettering — Tall man lettering puts capital letters into a drug name — glipiZIDE, glyBURIDE — so two look-alike names stop looking alike. FDA and ISMP each publish a list, and they are not the same list.
Source: PTCB — PTCE Content Outline, effective January 6, 2026 (the KA 1.2 statement "Therapeutic duplications", the KA 2.2 and 2.3 statements on controlled substances and prescription requirements, the KA 4.3 and 4.4 statements on NDC, lot, expiration and returns, and the KA 3.1/3.2 error-prevention statements, quoted verbatim); FDA label and NDC data read through openFDA and DailyMed; ISMP (the high-alert medication definition and the error-prone abbreviation list); USP <795> and <797>; the DEA Pharmacist's Manual (outline accessed 2026-10-03, verbatim; every fact below restates this course's own guides, which carry the per-source citations on their own pages (FDA, ISMP, USP and DEA each publish on its own schedule))