Six main-categories of errors were identified: 1) Wrong dose, 2) Wrong drug, 3) Dose(s) missed, 4)
Unauthorized or unordered drug, 5) Wrong route, 6) Drug administered despite documented allergy. Six maincategories of contributing factors on the individual levels were identified: 1) Negligence, forgetfulness or lack of
attentiveness, 2) Practice beyond scope, 3) Lack of knowledge, 4) Communication errors, 5) Proper protocol not
followed and 6) Disease or drug abuse. Six main categories on the system level were identified: 1) Organizational
routines and culture, 2) Location of medication and look-alike medication, 3) Role overload, 4) Interruption
or distraction, 5) Pressure from patient/patient's family or staff members and 6) Lack of adequate guidelines or
information