Concept Architecture
Concept
Theoretically, Near Miss Rate is a patient safety measure that quantifies the frequency of near miss events occurring within a defined healthcare population over a specified period. A near miss is an event that could have resulted in patient harm but did not, either by chance or because it was intercepted before reaching the patient. The concept is grounded in patient safety science, epidemiology and healthcare quality measurement and exists to monitor latent system failures and opportunities for safety improvement before harm occurs.
Mathematically, the Near Miss Rate is represented as the ratio of the number of reported near miss events to an appropriate denominator, such as patient-days, patient encounters, admissions or medication doses, multiplied by a standard scaling factor. The denominator is selected according to the healthcare setting and reporting framework to standardise comparisons across organisations.
In practice, Near Miss Rates are calculated using incident reporting systems and patient safety surveillance programmes. Events are classified according to recognised patient safety taxonomies before rates are monitored longitudinally, benchmarked internally or externally and analysed to identify system vulnerabilities and evaluate patient safety interventions.
Purpose
Used to monitor patient safety, identify latent system failures, evaluate safety improvement initiatives, benchmark organisational safety performance and support proactive risk management before patient harm occurs.
Mathematical Formulae
Primary Formula
Near Miss Rate = (Number of Near Miss Events � Number of Patient Encounters) ? k
where k is a reporting constant (commonly 1,000 or 10,000).
Supporting Formulae
Near Miss Rate per 1,000 Patient-Days = (Number of Near Miss Events � Total Patient-Days) ? 1,000
Near Miss Percentage = (Number of Near Miss Events � Number of Patient Encounters) ? 100
Related Mathematical Methods
- Incidence rate
- Incidence proportion
- Rate standardisation
- Time series analysis
- Statistical process control
- Safety surveillance analysis
Example
A hospital reports 145 near miss events during one quarter in which 28,600 patient encounters occur.
Near Miss Rate = (145 � 28,600) ? 1,000
= 5.07 near misses per 1,000 patient encounters
The organisation therefore reports a Near Miss Rate of 5.07 per 1,000 patient encounters, providing an indicator of safety reporting activity and opportunities for system improvement.
Excel Implementation
| Function | Example Formula | Health Economics Application |
|---|---|---|
| COUNTIF | =COUNTIF(B2:B500,"Near Miss") | Count reported near miss events. |
| COUNTA | =COUNTA(C2:C28601) | Count patient encounters. |
| COUNTIF/COUNTA | =(COUNTIF(B2:B500,"Near Miss")/COUNTA(C2:C28601))*1000 | Calculate the Near Miss Rate per 1,000 patient encounters. |
| AVERAGE | =AVERAGE(D2:D13) | Calculate the average monthly Near Miss Rate. |
| IF | =IF(E2>5,"High Reporting","Expected Range") | Compare Near Miss Rates across reporting periods or organisations. |
VBA (Optional)
Automate calculation of Near Miss Rates by clinical unit, incident category and reporting period while generating patient safety dashboards.
Sources
- World Health Organization. Conceptual Framework for the International Classification for Patient Safety.
- Agency for Healthcare Research and Quality. Patient Safety Network.
- Institute for Healthcare Improvement. Patient Safety Essentials Toolkit.
- OECD. Health Care Quality Indicators Project.
- Drummond MF, Sculpher MJ, Claxton K, Stoddart GL, Torrance GW. Methods for the Economic Evaluation of Health Care Programmes.
- Briggs A, Claxton K, Sculpher M. Decision Modelling for Health Economic Evaluation.
Related Concepts (2)
Library
Publications
1
The World Health Report 2000 — Health Systems: Improving Performance — World Health Organization, 2000 Edition ed., 2000 (World Health Organization)
The landmark WHO report that introduced a framework for assessing and ranking health-system performance across goals of health, responsiveness and fairness in financing — hugely influential (and much debated) in launching the field of health-system performance assessment.
Frequently Asked Questions (6)
What is the near-miss rate?
A measure of how frequently potential errors are identified and prevented before reaching a patient, an indicator of safety culture.
Source: AHRQ, Surveys on Patient Safety Culture
What does the near-miss rate measure?
The near-miss rate measures how frequently potential errors are identified and prevented before reaching a patient, so it tracks the frequency of caught errors, serving as an indicator of safety culture. This measurement of prevented errors defines it. So the near-miss rate is a measure of how frequently potential errors are identified and prevented before reaching a patient, an indicator of safety culture This focus on prevented errors is what sets the near-miss rate apart from measures of realised harm.
Source: AHRQ, Surveys on Patient Safety Culture
What events does the near-miss rate count?
The near-miss rate counts potential errors identified and prevented before reaching a patient, so it captures errors that were caught in time rather than harm that occurred. This focus on prevented errors defines it. So the near-miss rate counts potential errors identified and prevented before reaching a patient, measuring how frequently this happens as an indicator of safety culture This indication of culture is what makes the near-miss rate a signal of how an organisation handles errors.
Source: AHRQ, Surveys on Patient Safety Culture
What does the near-miss rate indicate?
The near-miss rate indicates safety culture, so how frequently potential errors are caught before reaching patients reflects how well an organisation notices and stops errors, signalling its safety culture. This indication of culture defines its purpose. So the near-miss rate indicates safety culture, measuring how frequently potential errors are identified and prevented before reaching a patient This dependence on staff noticing and acting is why the near-miss rate is read as a sign of safety culture.
Source: AHRQ, Surveys on Patient Safety Culture
Why does the near-miss rate reflect safety culture?
The near-miss rate reflects safety culture because catching potential errors before they reach patients depends on staff noticing and acting, so a higher rate of caught errors can signal a culture engaged with safety. This dependence on staff engagement is why it reflects culture. So the near-miss rate is an indicator of safety culture, measuring how frequently potential errors are identified and prevented before reaching a patient.
Source: AHRQ, Surveys on Patient Safety Culture
How does the near-miss rate relate to a good catch?
The near-miss rate relates to a good catch as its aggregate: a good catch is a single instance where a healthcare worker identifies and prevents a potential error from reaching a patient, and the near-miss rate measures how frequently such catches occur. So the near-miss rate counts good catches over time, connected as the measure that reflects how often potential errors are prevented This aggregation is what makes the near-miss rate the measure that counts good catches over time.
Source: AHRQ, Surveys on Patient Safety Culture
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Verified by Dr Darrin Baines
British health economist
Professional identity: darrinbaines.org
Verification date: 26 Feb 2026
Content version: 1.0.0
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