US · guidance
CMS SOM App. A, Tag A-0286
Patient Safety, Medical Errors & Adverse Events
§§482.21(a)(1), 482.21(a)(2), 482.21(c)(2), & 482.21(e)(3)
§482.21(a) Standard: Program Scope.
• The program must include, but not be limited to, an ongoing program that shows
measurable improvement in indicators for which there is evidence that it will… identify and
reduce medical errors.
• The hospital must measure, analyze, and track…adverse patient events….
§482.21(c) Standard: Program Activities.
(2) Performance improvement activities must track medical errors and adverse patient
events, analyze their causes, and implement preventive actions and mechanisms that
include feedback and learning throughout the hospital.
§482.21(e) Standard: Executive Responsibilities. The hospital’s governing body (or organized
group or individual who assumes full legal authority and responsibility for operations of the
hospital), medical staff, and administrative officials are responsible and accountable for
ensuring the following: …
(3) That clear expectations for safety are established.
Interpretive Guidance §§482.21(a)(1), 482.21(a)(2), 482.21(c)(2), & 482.21(e)(3)
Medical errors and adverse events
The reporting mechanism for medical errors and adverse events is at the discretion of the hospital.
CMS does not specify the type of reporting mechanism to be used, but expects that the system will permit
the hospital to track and analyze medical errors and adverse events in an effective and meaningful
manner. As appropriate, hospitals should educate all hospital staff and contract staff on what is
considered a medical error and an adverse event, as well as when and how to report these events.
CMS has adopted the following definition of an error from the Quality Interagency Coordination Task
Force (QuIC) (68 FR 3435, 3436, January 24, 2003):
“An error is defined as the failure of a planned action to be completed as intended or the use of a wrong
plan to achieve an aim. Errors can include problems in practice, products, procedures, and systems.”
There are many types of medical errors, including, but not limited to:
• Medication administration errors - wrong medication, wrong dosage, wrong patient, etc.;
• Surgical errors - wrong patient, wrong site, retained instrument, etc.;
• Equipment failure – defibrillator without working batteries, IV pump that results in inadvertent
dosing, alarms not working properly, etc.;
• Infection control errors – poor aseptic technique, incorrect processing of sterile instruments and
equipment, incorrect isolation practices, lack of standard precautions, etc.;
• Blood transfusion-related errors – wrong patient, wrong blood product administered, etc.; and
• Diagnostic errors – misdiagnoses leading to incorrect choice of therapy, failure to use an indicated
diagnostic test, misinterpretation of test results, failure to act properly on abnormal results.
Not every medical error results in harm to a patient; the error may be detected and addressed before a
harmful effect can occur (a “near miss”) or the consequence of the error may be minimal. From a
patient safety perspective, a near miss is considered an error and much can be learned from the near
miss in terms of system weaknesses that could, in the future, result in actual harm to patients.
Therefore, hospitals must track and analyze errors that result in near misses, and focus on their
prevention and reduction.
While the regulation also specifically calls for measuring, analyzing, and tracking of adverse events,
adverse events may or may not be preventable. A preventable adverse event is an injury caused by an
error. Section 482.70 defines an adverse event as “an untoward, undesirable, and usually unanticipated
event that causes death or serious injury, or the risk thereof.”
Analysis of Causes of Medical Errors and Adverse Events
Hospitals should analyze medical errors and adverse events to determine the cause(s) by using a
systemic approach for determining the cause of the error and for implementing appropriate preventive
actions.
Implementing Improvement/Preventive Strategies
After the systemic analysis of the error or adverse event has led to the identification of the cause of the
event, hospitals should develop and implement preventive actions to improve the quality and safety
associated with the event or the error. Preventive actions include, but are not limited to, changes in
policies and procedures, repairing or replacing equipment, staff education and training, etc. Where
appropriate, the hospital should make all affected staff aware of the strategies and related actions it has
implemented to correct and prevent specific errors and adverse events, and also provide applicable
training. Hospitals should be able to provide evidence of the implemented changes, such as documented
staff education and training, documentation of new or revised policies, evidence that equipment has
been repaired or replaced, etc.
Evaluating Changes and Sustaining Improvement
The hospital should also have a method to assess whether the strategies and actions it has implemented
resulted in improved outcomes and that those improved outcomes are sustained over time. This means
the hospital should collect data that enables the hospital to determine whether indicators, related to a
specific area targeted for change, actually demonstrated an improvement after implementation of the
changes.
For example, the hospital should continue to periodically collect data on proper hand hygiene and then
analyze the data to determine if the solution has resulted in sustained improvement in handwashing
compliance. If the analysis of the periodic collection of handwashing data shows that the solution has
not resulted in a sustained improvement over an appropriate period of time, a new or revised
strategy/solution must be implemented, with subsequent data collection and monitoring to evaluate the
effectiveness of the new solution.
Prospective hospitals applying for initial certification in Medicare
A facility seeking Medicare program initial certification as a hospital may not have been in operation
long enough to demonstrate extensive internal data collection for the identification of opportunities for
improvement based on the monitoring data. However, it must be able to show that it has an active data
collection and analysis infrastructure in place, and indicate when it expects to have sufficient data to
begin analysis. In addition, because hospitals may utilize quality indicators from outside sources to
prioritize QAPI program activities, an initial applicant would still be expected to provide evidence of
implementing improvement actions based on selected indicators from outside sources.
Survey Procedures
• Ask to see evidence of the medical error/adverse event reporting system. Ask for a copy of
the medical error and adverse event reporting policy. Ask for a demonstration of how to use
the system and how the system is able to organize the reported data for meaningful analysis.
Can the system organize the data by type of error/adverse event?
Can the system organize the data by dates to show trends over time?
Can the system organize the data by shift, by unit where the error occurred, etc.?
• Ask to see evidence of hospital-wide staff education and training regarding what errors and
adverse events must be reported and how to report them. Look at the materials used for
education and training.
Are there training records to show staff received the training?
• Interview staff in various units to assess their understanding of identifying and reporting
medical errors and adverse events.
• Select a sample of several (at least three) adverse events or errors the hospital has tracked
and ask to see written evidence it has used a systemic approach (e.g., root cause analysis
(RCA)) to analyze the cause of the events and errors), implemented changes based on the
identified causes to prevent further events or errors, conducted periodic data collection to
verify if the changes resulted in improvements, and analyzed the post-implementation data to
assess whether the improvement (if there was an improvement) was sustained over time.
History
Rev. 238; Issued: 03-20-26; Effective: 09-05-25; Implantation: 09-05-25
Provenance
- Source
- cms.gov
- Retrieved
- 2026-07-22
- Edition
- som-2026-07-22
- Content hash
aeafada439716234654fa2cd248bbb949cda039e4f32b506a99a05b1376635f9
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