NHS DNA Rate Calculator
This operational calculator estimates a Did Not Attend (DNA) rate for NHS appointment data. NHS England describes a DNA as a missed appointment and recommends monitoring DNA rates to understand access barriers, variation and opportunities to improve clinic use.
Calculate your DNA rate
Important: use a denominator that matches the reporting definition you are analysing. For national outpatient reporting, NHS England uses specific attendance-status and administrative-category rules; a simple local appointment total may not reproduce a nationally reported rate.
DNA rate formula
For a simple local calculation: DNA rate (%) = DNA appointments ÷ appointments in the chosen denominator × 100.
NHS England’s national outpatient definition is more specific. It includes attendance status 3 (did not attend with no advance warning) and status 7 (arrived late and could not be seen) in the DNA numerator, with defined eligible outpatient attendance statuses in the denominator and exclusions for certain administrative events.
Worked example
If a clinic uses a local dataset containing 1,000 eligible appointments and 75 are classified as DNAs, the simple rate is 75 ÷ 1,000 × 100 = 7.5%.
How NHS services should use DNA rates
NHS England recommends establishing a baseline over time and examining variation by service factors such as specialty, appointment time, site, day of week and notice period, alongside demographic and access factors. A low DNA rate should not automatically be treated as proof that a service is accessible.
Why patients may miss appointments
NHS England notes that missed appointments can have many causes, including communication problems, difficulty cancelling or rearranging, work or caring responsibilities, transport, cost and accessibility. DNA analysis should therefore support service improvement rather than simply attributing missed appointments to patient behaviour.
Limitations
This calculator is an operational percentage tool, not an official NHS reporting submission. Local definitions can differ from national outpatient reporting definitions. Validate the numerator, denominator, exclusions and reporting period against the dataset and specification you are using.
Authoritative Sources
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FAQs
What does DNA mean in the NHS?
DNA means Did Not Attend. NHS England uses the term for missed appointments; in children’s services, Was Not Brought may be used.
How do I calculate a simple DNA rate?
Divide the number of DNA appointments by the number of appointments in the chosen denominator, then multiply by 100.
Are patient cancellations DNAs?
A patient who rearranges or cancels in advance should not simply be treated as a no-warning DNA. Always use the reporting definition relevant to your dataset.
Is this the exact national NHS reporting calculation?
No. National outpatient reporting uses defined attendance-status, administrative-category and exclusion rules. This calculator provides a transparent local percentage calculation and explains the distinction.
Disclaimer: This is an independent operational calculator and not an NHS England reporting system. Check your organisation’s data specification before using the result for formal reporting.