Background
The WHO’s ICD-10 defined transient ischaemic attack (TIA) as neurological dysfunction lasting less than 24 hours, whereas stroke was defined as symptoms lasting more than 24 hours. When ICD-11 came into effect in 2022, both definitions changed to a ’tissue-based’ approach, shifting stroke from a condition diagnosed by clinical symptoms to one diagnosed based on brain imaging findings. Under ICD-11, patients with neurological symptoms lasting less than 24 hours but with positive neuroimaging are now classified as having stroke rather than TIA. These changes will have profound impacts on healthcare globally: more people with stroke will be identified early for preventative treatment; care may shift from hospitals to outpatient settings for milder strokes; and MRI use will be motivated over less effective CT scanning. However, the magnitude of these impacts remains uncertain, with implications for long-term outcomes, healthcare costs, and health inequalities not yet well understood.
Novelty & Importance
This PhD will leverage two complementary national datasets: the South London Stroke Register (SLSR) and the Sentinel Stroke National Audit Programme (SSNAP). The SLSR is a population-based prospective cohort study operating since 1995, providing detailed baseline assessment, physician-confirmed diagnoses, and long-term follow-up extending beyond 15 years. Since 2022, SLSR has adopted ICD-11 criteria, providing unique prospective data in a diverse, multi-ethnic urban population. SSNAP captures approximately 85,000 stroke episodes annually across England, Wales, and Northern Ireland, but only includes hospital-admitted cases with limited long-term follow-up. By combining SLSR’s detailed phenotyping with SSNAP’s national scale, this research will generate high-quality estimates of stroke burden under ICD-11, critical for informing NHS resource allocation and service planning. The project innovates through: developing novel statistical methods for combining detailed local data with national datasets; pioneering living systematic review methods in stroke epidemiology; and advancing knowledge translation through co-designed data visualisation tools with end-users.
Aims & Objectives
Aim 1: To systematically identify, synthesise, and continuously update evidence on the epidemiological impact of ICD-11 stroke definitions through a living systematic review.
Aim 2: To estimate the incidence of ICD-11-defined stroke in South London, characterise the clinical phenotype and care pathways of newly-included patients, and describe their short and long-term outcomes.
Aim 3: To develop and validate statistical models leveraging detailed SLSR data to generate national and regional projections of ICD-11 stroke incidence, healthcare utilisation, disability burden, and mortality.
Aim 4: To translate research findings into actionable intelligence through co-designed interactive dashboards for commissioners, policymakers, and service providers.