Third Next Available Appointment


Learning Objective: To understand the value of measuring third next appointment availability, and how to do it.

What is Third Next Available Appointment?

Third next available appointment (TNAA) is a measure of the number of days a patient must wait to access a routine appointment.


Why use Third Next Available Appointment?

Access is an important characteristic of effective primary care as delays are associated with poor patient experience and higher use of secondary care.

Measuring the third next available appointment, not the first or second, reduces the impact of chance on access i.e. if the first appointment available is a cancellation. Consequently, the time to the third next available appointment is more likely to be stable in the long-run.


How to measure third next available appointment

The first step is to understand the current state of access, enabling you to test changes to improve access if required.

The TNAA for each GP and NP should be sampled at the same time and day of the week, once a week (Tuesday at 10am is a good option). The person responsible for calculating TNAA should follow these steps:

1. Go to a dummy patient in the PMS.

2. Count the number of days between now and the third next available appointment slot for each GP and NP.

3. If the third next available appointment is on the same day, then the TNAA is 0. If the third next available appointment is on the next day then the TNAA is 1, etc.

4. At the end of each week calculate a weekly average for each GP/NP,  and for the practice.

Each calendar day, including public holidays and weekends, should be counted, even if the GP/NP does not normally work that day. Remember, this is from the patients’ perspective of average wait time for a routine appointment. If your practice blocks off urgent or same day appointments these should not be counted. If a GP/NP is on leave or sick for more than three days do not count their TNAA as it will skew your average, unless a locum is covering those sessions.


Days to third next available appointment


Week 1

Week 2

Week 3

Week 4

GP 1





GP 2





NP 1
















How to measure success

A TNAA of two days or under is considered the gold standard amongst some organisations, however a practice should determine their own access standards. For example, is it critical for a patient to access the practice for a driving licence medical within two days? TNAA provides data around access and should first provoke discussion about what is an appropriate wait time for patients. Remember too there is a complex relationship between supply and demand – for example, increasing the number of available appointments by increasing clinical FTE may not reduce TNAA if there is significant unmet demand.

If a practice does wish to improve access, then set a wait time goal. TNAA is an important measure to track the impact of improvements on this goal. PDSA cycles should be used to introduce and test small scale changes. Some changes which may have a positive impact on access are:

  • Increasing patient portal uptake and use.

  • Re-distributing patients among clinicians, especially if long-term staff have much higher TNAA than new staff.

  • Extended opening hours (if this increases the number of available appointments).

  • Considering pre-work to reducing the number of DNAs or wasted appointments (i.e. blood tests are done before appointments).


Helpful Tips

A useful table to record TNAA is shown below.

Measuring third next available appointment should take around 2 minutes of your day, once a week.

The simplest way to see trends in TNAA data is to plot a line graph over time.