How Will the New Stroke Definition Change Case Counts Across the UK?

Key Findings from New Research

The new ICD-11 stroke definition will capture new strokes that are currently labelled as TIAs, increasing projected stroke incidence by approximately 4.2% uniformly across all four UK nations, an estimated 2,771 additional cases per year. The greatest absolute burden will fall on regions with older populations (rural Scotland, Wales, South West England), while projected rates in this analysis might be overestimated by 10–14% in predominantly White regions due to the ethnic diversity of our South London source population. This diagnostic change is happening alongside a broader rise in stroke incidence driven by inequalities in cardiovascular risk, a trend that is larger and potentially modifiable. Planning for ICD-11 must address both.

How Will the New Stroke Definition Change Case Counts Across the UK?

A new international classification will count thousands of strokes currently labelled as transitory ischaemic attacks or TIA. We mapped what this means for every region of the UK.

What is changing?

Until now, a stroke diagnosis required symptoms lasting at least 24 hours. The new international classification (ICD-11) changes this: if a brain scan shows a lesion, even a brief episode now counts as a stroke.

This means many patients currently told they had a TIA will be reclassified as stroke survivors. Our previous research found this group tends to be younger, with milder presentations, but with real brain damage that puts them at risk of a more serious stroke in the future.

What did we find?

Using data from the South London Stroke Register, we applied stroke rates to UK Census populations across all four nations, 33 health regions, and 69 sub-regions.

The relative increase in every part of the UK is approximately a 4.2% rise, adding around 2,771 cases nationally each year. But where people live still matters, as areas with older populations, like rural Wales, Scotland, and South West England, will see the most additional cases. Stroke rates across sub-regions range from 93 per 100,000 in London to 175 in Powys, Wales.

Our projections are based on South London rates, which come from a more ethnically diverse population than most UK regions. This means projections may slightly overestimate rates in areas where predominantly people from White ethnicity live; adjusting for ethnicity reduced projections by around 10–14% in those regions.

The bigger picture

This diagnostic change is happening at the same time as a broader rise in stroke incidence, driven by inequalities in cardiovascular risk, particularly for Black Caribbean and Black African communities. That underlying trend is larger than the reclassification effect, and unlike a change in definitions, it is preventable.

Explore the data for your region

We have built an interactive dashboard where you can explore projected stroke rates at country, regional, and sub-regional level across the UK. Click any region to see detailed figures.

What this means for health services

Many of these newly diagnosed patients will be seen in outpatient clinics rather than admitted to hospitas. These settings are not currently monitored by national stroke audit SSNAP. Without that oversight, patients risk missing secondary prevention that could stop a future, more serious stroke.

• Expand stroke audit to outpatient care, so newly classified patients are not lost to follow-up.
• Improve MRI access in rural and underserved regions, where the projected burden is highest but imaging availability is lowest, as these newly classified stroke cases are mostly diagnosed through MRI.
• Invest in prevention, particularly in communities where cardiovascular risk is highest, as appart from this rise in stroke due to the change on definition, the underlying rising trend due to cardiovascular risk factors inequality will have a greater impact on future stroke burden than any change in definitions.