Darllenwch y dudalen hon yn Gymraeg.

In October, the Cabinet Minister for Health and Care announced a change to the way waiting times are measured for some patients attending emergency departments in Wales. This change affects the official statistics used to monitor emergency department performance.

In this update, we explain what has changed, the expected impact on published statistics, and the implications for comparisons over time and with other UK countries.

What has changed

For most patients attending an emergency department, waiting time is measured as the total time spent in the department – from arrival until discharge, admission to hospital, or transfer to another healthcare provider.

Until recently, there were some exceptions to this approach. For a small proportion of patients, the waiting time ‘clock’ could stop before they physically left the department. Most of these cases were known as ‘clinical exceptions’ – patients who required a period of observation or recovery under the care of emergency department teams. For these patients, as well as for patients awaiting hospital transport, the clock could be stopped when treatment ended. Examples of clinical exceptions include:

• patients awaiting the results of tests that must be carried out several hours after the onset of chest pain
• patients recovering following sedation
• patients requiring a period of observation after a head injury
• patients receiving ongoing lifesaving treatment

On 1 October 2026, the policy allowing earlier clock stops for clinical exceptions and patients awaiting transport was removed. As a result, waiting times for all patients are now based on the total time spent in an emergency department, regardless of whether part of that time involves observation, recovery or waiting for transport.

Our official statistics measure performance based on the policies in place, so the statistics we publish from November will reflect this policy change. This will affect the published measures for:

• the percentage of attendances completed within 4 hours
• the number of attendances exceeding 12 hours
• average waiting times

What impact this will have

Statistics from October 2026 onwards will not be directly comparable with the previous figures. We expect the change will affect recorded waiting times for around 3% of emergency department attendances.

To support interpretation and estimate the size of the discontinuity created by this policy change, we have examined historical data using both the previous and new policies. Our analysis estimates that, under the new policy:

• the percentage of attendances recorded as completed within 4 hours would fall by around 3 percentage points compared with the previous policy
• the number of attendances recorded as lasting more than 12 hours would rise by around 2 to 3%
• median waiting times would increase by around 3 minutes, or 2%

Ordinarily, month-to-month changes in the figures reflect genuine improvements or deteriorations in performance. However, any fall in the performance measures from October is likely to largely reflect the policy change and should not necessarily be interpreted as a deterioration in emergency department performance or an increase in the time patients spend in emergency departments.

The chart below illustrates the difference between the two policies from October 2021 to September 2026 in 4-hour waits, the most widely reported performance measure.

Figure 1: percentage of patients waiting less than 4 hours in emergency departments under the previous and new policies, October 2021 to September 2026

Description of figure 1: a line chart comparing the percentage of patients admitted, transferred or discharged within 4 hours under the previous policy, which excluded some time after treatment ended for clinical exceptions and patients awaiting transport, and the new policy, which measures total time spent in the department.

The difference has narrowed in recent years, from around 8 percentage points in early 2023 to 3 percentage points recently. This reflects a reduction in the use of clinical exceptions over that period following work to improve compliance with policy guidance.

Comparability with other UK countries

The change also has implications for comparisons between Wales and other UK nations.

Previous work to assess comparability (Office for National Statistics) found that emergency department waiting-time measures in Wales, England and Scotland were broadly comparable for major emergency departments because similar principles were applied when measuring waiting times. From October 2026, this will no longer be the case, meaning direct comparisons should no longer be made. Conversely, the revised Welsh policy will be more closely aligned with the policy in Northern Ireland, improving comparability between these two countries.

We will work with colleagues across the UK statistical system to ensure that existing guidance on cross-country comparisons is updated to reflect this change.

Helping users understand changes to the statistics

Alongside this update, we will provide information about the change in our monthly statistical report, including analysis of the size of the discontinuity and guidance on interpreting trends over time.

The policy change provides a new basis for monitoring activity and performance in Wales’ emergency departments. Our focus as statisticians will be on ensuring that users understand what has changed, the scale of its impact, and the implications for comparisons over time and between countries.

As always, our aim is to provide statistics that are trustworthy, high quality and of public value, supporting informed discussion about the performance of NHS services in Wales.

Stephanie Howarth
Chief statistician