Definitions and Scores
Below, you will find a glossary of common patient safety terms as well as the AHRQ Common Formats Harm Scores.
Glossary of Patient Safety Definitions
 Term  Definition
Adverse Event

An injury caused by medical care An injury that was caused by medical management or
complication instead of the underlying disease and that resulted in prolonged hospitalization
or disability at the time of discharge from medical care, or both


• pneumothorax from central venous catheter placement

• anaphylaxis to penicillin

• postoperative wound infection

• hospital-acquired delirium (or "sundowning") in elderly patients

Identifying something as an adverse event does not imply "error," "negligence," or poor
quality care. It simply indicates that an undesirable clinical outcome resulted from some
aspect of diagnosis or therapy, not an underlying disease process. Thus, pneumothorax
from central venous catheter placement counts as an adverse event regardless of insertion
technique. Similarly, postoperative wound infections count as adverse events even if the
operation proceeded with optimal adherence to sterile procedures, the patient received
appropriate antibiotic prophylaxis in the perioperative setting, and so on


Adverse Outcome 
Undesired patient outcome of health care; clinical complication of health care (which may
or may not be a patient safety incident)
Chain of events
A series of events in which one event leads to another with the possibility that the final event
reaches the patient; collectively, an event episode
Close Call (Near Miss) An event or situation that did not produce patient injury, but only because of chance. This
good fortune might reflect robustness of the patient (e.g., a patient with penicillin allergy
receives penicillin, but has no reaction) or a fortuitous, timely intervention (e.g., a nurse
happens to realize that a physician wrote an order in the wrong chart).
Complication See Adverse Outcome
Contributing Factor A circumstance, action or influence which is thought to have played a part in the origin or
development of an incident or to increase the risk of an incident

An act of commission (doing something wrong) or omission (failing to do the right thing) that
leads to an undesirable outcome or significant potential for such an outcome. For instance,
ordering a medication for a patient with a documented allergy to that medication would be an
act of commission. Failing to prescribe a proven medication with major benefits for an eligible
patient (e.g., low-dose unfractionated heparin as venous thromboembolism prophylaxis for a
patient after hip replacement surgery) would represent an error of omission.

Errors of omission are more difficult to recognize than errors of commission but likely represent
a larger problem. In other words, there are likely many more instances in which the provision of
additional diagnostic, therapeutic, or preventive modalities would have improved care than there
are instances in which the care provided quite literally should not have been provided. In
many ways, this point echoes the generally agreed-upon view in the health care quality
literature that underuse far exceeds overuse, even though the latter historically received
greater attention. In addition to commission vs. omission, three other dichotomies commonly
appear in the literature on errors: active failures vs. latent conditions, errors at the sharp end
vs. errors at the blunt end, and slips vs. mistakes

Event Episode Single event or chain of events from point of origin of a process failure or error within a health
care organization to its termination in a near miss or incident
Failure Mode and Effect Analysis (FMEA)

A common process used to prospectively identify error risk within a particular process.
FMEA begins with a complete process mapping that identifies all the steps that must occur
for a given process to occur (e.g., programming an infusion pump or preparing an
intravenous medication in the pharmacy). With the process mapped out, the FMEA then
continues by identifying the ways in which each step can go wrong (i.e., the failure modes
for each step), the probability that each error will be detected (i.e., so that it can be corrected 
before causing harm), and the consequences or impact of the error not being detected. The
estimates of the likelihood of a particular process failure, the chance of detecting such failure,
and its impact are combined numerically to produce a criticality index.

This criticality index provides a rough quantitative estimate of the magnitude of hazard
posed by each step in a high-risk process. Assigning a criticality index to each step allows
prioritization of targets for improvement. For instance, an FMEA analysis of the medication-
dispensing process on a general hospital ward might break down all steps from receipt of
orders in the central pharmacy to filling automated dispensing machines by pharmacy
technicians. Each step in this process would be assigned a probability of failure and an
impact score, so that all steps could be ranked according to the product of these two
numbers. Steps ranked at the top (i.e., those with the highest criticality indices) would be
prioritized for error proofing.

FMEA makes sense as a general approach and it (or similar prospective error-proofing
techniques) has been used in other high-risk industries. However, the reliability of the
technique is not clear. Different teams charged with analyzing the same process may
identify different steps in the process, assign different risks to the steps, and consequently
prioritize different targets for improvement.

Harm Physical or psychological injury (including increased anxiety), inconvenience (such as
prolonged treatment), monetary loss, and/or social impact, etc. suffered by a person.
Human Factors Human factors engineering is the discipline that attempts to identify and address safety
problems that arise due to the interaction between people, technology, and work environments.
Human Factors Principles
  1. Avoid reliance on memory
  2. Simplify
  3. Standardize
  4. Use constraints and forcing functions
  5. Use protocols & checklists wisely
  6. Improve information access
  7. Reduce handoffs
  8. Increase feedback
Incident A patient safety event that reached the patient, whether or not the patient was harmed
Latent Error (or Latent Condition) The terms active and latent as applied to errors were coined by Reason. Latent
errors (or latent conditions) refer to less apparent failures of organization or design
that contributed to the occurrence of errors or allowed them to cause harm to patients.
For instance, whereas the active failure in a particular adverse event may have been
a mistake in programming an intravenous pump, a latent error might be that the
institution uses multiple different types of infusion pumps, making programming errors
more likely. Thus, latent errors are quite literally "accidents waiting to happen." Latent
errors are sometimes referred to as errors at the blunt end, referring to the many layers
of the health care system that affect the person "holding" the scalpel. Active failures,
in contrast, are sometimes referred to as errors at the sharp end, or the personnel and
parts of the health care system in direct contact with patients.
Medical Device A medical device is any instrument, apparatus, implement, machine, contrivance,
implant, in vitro reagent, or other similar or related article, including any component,
part, or accessory, intended for use in the diagnosis of disease or other conditions, or
in the cure, mitigation, treatment, or prevention of disease, or intended to affect the
structure or any function of the body, and which does not achieve its primary intended
purposes through chemical action within or on the body and which is not dependent
upon being metabolized for the achievement of its primary intended purposes.
Near Miss (also see Close Call) A patient safety event that did not reach the patient. For example: discovery of a
dispensing error by a nurse as part of the process of administering the medication
to a patient (which if not discovered would have become an incident); discovery of
a mislabeled specimen in a laboratory (which if not discovered might subsequently
have resulted in an incident).
Patient Outcome  he result of receiving a health care service, especially as related to a patient’s health
status; usually refers to post-process results or measurements (the observed results
of an intervention) whether or not one can confidently attribute those results to the
preceding process (intervention).
Patient outcome Harm Scale A systematic method to assess and to represent the extent of a patient’s health loss
(including anxiety, inconvenience, etc.) at a point in time, especially as related to residual
harm following a patient safety incident and any rescue actions that might have been
attempted consequently
Patient Safety The avoidance, prevention, and amelioration of adverse outcomes or injuries stemming
from the processes of health care . These events include “errors,” “deviations,” and
“accidents.” Safety emerges from the interaction of the components of the system; it
does not reside in a person, device, or department. Improving safety depends on learning
how safety emerges from the interactions of the components. Patient safety is a subset
of health care quality
Patient Safety Evaluation System (PSES) The collection, management, or analysis of information for reporting to a patient
safety organization
Patient Safety Event Something that happens to or involves a patient; encompasses patient safety incident
and near miss
Patient Safety Incident A patient safety event that reached a patient and either resulted in no harm (no harm
incident) or harm (harm incident). The concept “reached a patient” encompasses
any action by a health care practitioner or worker or health care circumstance that
exposes a patient to harm. For example: if a nurse gives a patient an incorrect medication
to take and the patient recognizes it as such and refuses to take it, an incident has occurred
Patient Safety Work Product (PSWP)

Patient safety work product includes any data, reports, records, memoranda, analyses
(such as root cause analyses), or written or oral statements (or copies of any of
this material), which could improve patient safety, health care quality, or health care
outcomes, that are assembled or developed by a provider for reporting to a PSO and
are reported to a PSO. It also includes information that is documented as within a
patient safety evaluation system that will be sent to a PSO and information developed
by a PSO for the conduct of patient safety activities.

However, patient safety work product does not include a patient’s medical record,
billing and discharge information, or any other original patient or provider information;
nor does it include information that is collected, maintained, or developed separately,
or exists separately, from a patient safety evaluation system.

Patient Safety Work Product must not be disclosed, except in very specific circumstances
and subject to very specific restrictions.

Process A particular method of doing something, generally involving a number of steps or
operations, that results in an outcome or produces an output
Rescue Action Action taken or started within the first 24 hours after the discovery of a patient
safety incident that is intended to prevent, to minimize, or to reverse harm to the
affected patient
Residual Harm Estimated harm to a patient’s health subsequent to any attempted rescue action
taken or started within 24 hours after the discovery of an incident
Risk The product of 2 dimensions: 1) probability of an event’s occurrence in a specified
period, such as a year, and 2) the harm that would typically result if the event were to
Root Cause Analysis Initially developed to analyze industrial accidents, root cause analysis is now widely
deployed as an error analysis tool in health care. A central tenet of RCA is to identify
underlying problems that increase the likelihood of errors while avoiding the trap of
focusing on mistakes by individuals
Safeguard Aspect of a health care process that is designed to prevent harm from reaching a patient
in the event of a failure or error (including the failure of a fail-safe).
Safety Culture

A culture that exhibits the following five high-level attributes that health care professionals
strive to operationalize through the implementation of strong safety management systems.

  1. A culture where all workers (including front-line staff, physicians, and administrators)
    accept responsibility or the safety of themselves, their coworkers, patients, and
  2. [A culture that] prioritizes safety above financial and operational goals.
  3. [A culture that] encourages and rewards the identification, communication, and
    resolution of safety issues.
  4. [A culture that] provides for organizational learning from accidents.
  5. [A culture that] provides appropriate resources, structure, and accountability to
    maintain effective safety systems
Sentinel Event An adverse event in which death or serious harm to a patient has occurred; usually
used to refer to events that are not at all expected or acceptable—e.g., an operation on
the wrong patient or body part. The choice of the word sentinel reflects the egregiousness
of the injury (e.g., amputation of the wrong leg) and the likelihood that investigation of
such events will reveal serious problems in current policies or procedures.
Severity of Harm The extent of harm at a point in time; often categorized as none, mild, moderate, severe,
or death

Refer to signals for detecting likely adverse events. Triggers alert providers involved in
patient safety activities to probable adverse events so they can review the medical
record to determine if an actual or potential adverse event has occurred. For instance,
if a hospitalized patient received naloxone (a drug used to reverse the effects of narcotics),
the patient probably received an excessive dose of morphine or some other opiate. In
the emergency department, the use of naloxone would more likely represent treatment
of a self-inflected opiate overdose, so the trigger would have little value in that setting.
But, among patients already admitted to hospital, a pharmacy could use the administration
of naloxone as a "trigger" to investigate possible adverse drug events.

In cases in which the trigger correctly identified an adverse event, causative factors can
be identified and, over time, interventions developed to reduce the frequency of particularly
common causes of adverse events. The traditional use of triggers has been to efficiently
identify adverse events after the fact. However, using triggers in real time has tremendous
potential as a patient safety tool. In a study of real-time triggers in a single community
hospital, for example, more than 1000 triggers were generated in 6 months, and
approximately 25% led to physician action and would not have been recognized without
the trigger.

As with any alert or alarm system, the threshold for generating triggers has to balance
true and false positives. The system will lose its value if too many triggers prove to be
false alarms. This concern is less relevant when triggers are used as chart review tools.
In such cases, the tolerance of false alarms depends only on the availability of sufficient
resources for medical record review. Reviewing four false alarms for every true adverse
event might be quite reasonable in the context of an institutional safety program, but
frontline providers would balk at (and eventually ignore) a trigger system that generated
four false alarms for every true one.

Underuse, Overuse, Misuse

Underuse refers to the failure to provide a health care service when it would have
produced a favorable outcome for a patient. Standard examples include failures to provide
appropriate preventive services to eligible patients (e.g., Pap smears, flu shots for
elderly patients, screening for hypertension) and proven medications for chronic illnesses
(steroid inhalers for asthmatics; aspirin, beta-blockers, and lipid-lowering agents for
patients who have suffered a recent myocardial infarction).

Overuse refers to providing a process of care in circumstances where the potential for
harm exceeds the potential for benefit. Prescribing an antibiotic for a viral infection like a
cold, for which antibiotics are ineffective, constitutes overuse. The potential for harm includes
adverse reactions to the antibiotics and increases in antibiotic resistance among bacteria
in the community. Overuse can also apply to diagnostic tests and surgical procedures.

Misuse occurs when an appropriate process of care has been selected but a preventable
complication occurs and the patient does not receive the full potential benefit of the
service. Avoidable complications of surgery or medication use are misuse problems. A
patient who suffers a rash after receiving penicillin for strep throat, despite having a known
allergy to that antibiotic, is an example of misuse. A patient who develops a pneumothorax
after an inexperienced operator attempted to insert a subclavian line would represent
another example of misuse.

Unintentionally Retained Item Foreign object introduced into the body during a surgical operation or another invasive
procedure, without removal prior to finishing the surgery or procedure, that the surgeon
or other practitioner did not intend to leave in the body
Unnecessary Harm Health care-associated harm that was not expected to result from a patient’s treatment
plan; harm resulting from an incident

Unplanned Intervention

An intervention that was not part of a patient’s treatment plan prior to the event that
necessitated the additional intervention
Unsafe Condition Any circumstance that increases the probability of a patient safety event; includes a
defective or deficient input to or environment of a care process that increases the risk of
an unsafe act, care process failure or error, or patient safety event. An unsafe condition
does not involve an identifiable patient. For example, an out-of-date medicine on a shelf
represents an unsafe condition. It might be given to a patient, but the identity of such patient
is unknown at the time of discovery. The attempt to administer the out-of-date medicine to
a patient would either represent a near miss (if not administered) or an incident (if administered).
Other examples include look alike medications or confusing equipment.

Source: Agency for Healthcare Research and Quality (AHRQ). Users guide: version 1.2: AHRQ Common Formats for patient safety
organizations [online]. 2013 [cited 2014 Sep 16].

AHRQ Common Formats Harm Scores (Version 1.2)


 A Death: death at time of assessment
    B Severe harm: bodily or psychological injury (including pain or disfigurement) that interferes significantly with functional ability or quality of life
 C Moderate harm: bodily or psychological injury adversely affecting functional ability or quality of life, but not at the level of severe harm
 D Mild harm: minimal symptoms or loss of function, or injury limited to additional treatment, monitoring, and/or increased length of stay
 E No harm: event reached patient, but no harm was evident
 F Unknown

 Source: Agency for Healthcare Research and Quality (AHRQ). Users guide: version 1.2: AHRQ Common Formats
 for patient safety organizations [online]. 2013 [cited 2014 Sep 16].


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