Risk of death from stroke falls by 24%

Summary: Between 2000 and 2015, the rate of ischemic strokes decreased by 43%, with the risk of death falling by 24%. Researchers attribute the declines to improved treatment options.

Source: National Institute for Health Research

Thousands more patients each year are surviving strokes, as the risk of death and disability after a stroke fell significantly between 2000 and 2015, according to analysis by Guy’s and St Thomas’ researchers.

The study, published in PLOS Medicine, looked at data from south London patients who had an ischaemic stroke – one caused by a blood clot – between 2000 and 2015. The team attribute the reduced risk to improvements in care and medication.

After adjustments for population changes, the research showed that the risk of death from stroke fell by 24% over the 15 year period, with the one-year death rate dropping from 32.6% in 2000 to 20.15% in 2015. The one year death rate is the incidence of death within one year of the stroke. The risk of disability after a stroke fell by 23%, from 34.7% in 2000 to 26.7% in 2015.

With around 52,000 people having ischaemic strokes nationwide each year, the team arrived at a figure of 6,300 more patients annually surviving their stroke for over a year, and 3,200 fewer patients each year have a disability as a result of a stroke.

Stroke is a serious condition that occurs when blood supply to part of the brain is cut off. Stroke is the fourth single leading cause of death in England and Wales, and the third biggest cause of death in Scotland and Northern Ireland, with almost 38,000 people dying as a result of stroke in the UK in 2016.

The researchers used data from the South London Stroke Register, which collected data from patients in Lambeth and Southwark. They looked particularly at data from the 3,128 patients who had an ischaemic stroke. Previous analysis of the same source had shown that between 2000 and 2015 the rate of strokes in the area decreased by 43%, with the risk of death from stroke falling by 24%.

The paper showed that the risk of death and disability had reduced for all genders, and for both black and white patients.

Dr Yanzhong Wang, Reader in Medical Statistics at King’s College London and author of the study said: “It’s really positive news to see that for patients who do have a stroke, the risk of death and disability is decreasing. Alongside our previous work showing a reduction in the rate of strokes it shows that, although there is still more to do, trends are moving in the right direction.

This shows a head and a lightening bolt
Stroke is a serious condition that occurs when blood supply to part of the brain is cut off. The image is in the public domain.

“We think the change is due to improvements to the way we treat stroke, such as higher admission rates to hospital, increased use of CT and MRI scans, and more frequent treatment with thrombolytic and anticoagulant medications in the acute phase of stroke. We also believe that a shift towards patients having less severe strokes, perhaps caused by improved public health, could also play a role in the change.

“We’re really grateful to all the patients who have taken part in the South London Stroke Register. Their valuable input is giving us an incredibly detailed understanding of stroke rates, which can help us treat and prevent strokes in the future.”

The South London Stroke Register has been looking at the number of strokes recorded among the 350,000 people in south London since 1995. The register uses data sources including anonymous data from A&E records and data collected by specially trained doctors, nurses and field workers. The research was supported by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care South London at King’s College Hospital NHS Foundation Trust and by the NIHR Biomedical Research Centre based at Guy’s and St Thomas’ NHS Foundation Trust and Kings College London.

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Source:
National Institute for Health Research
Media Contacts:
Anna Perman – National Institute for Health Research
Image Source:
The image is in the public domain.

Original Research: Open access
“Long-term trends in death and dependence after ischaemic strokes: A retrospective cohort study using the South London Stroke Register (SLSR)”. Hatem A. Wafa, Charles D. A. Wolfe, Ajay Bhalla, Yanzhong Wang.
PLOS Medicine doi:10.1371/journal.pmed.1003048.

Abstract

Long-term trends in death and dependence after ischaemic strokes: A retrospective cohort study using the South London Stroke Register (SLSR)

Background
There have been reductions in stroke mortality over recent decades, but estimates by aetiological subtypes are limited. This study estimates time trends in mortality and functional dependence by ischaemic stroke (IS) aetiological subtype over a 16-year period.

Methods and findings
The study population was 357,308 in 2011; 50.4% were males, 56% were white, and 25% were of black ethnic backgrounds. Population-based case ascertainment of stroke was conducted, and all participants who had their first-ever IS between 2000 and 2015 were identified. Further classification was concluded according to the underlying mechanism into large-artery atherosclerosis (LAA), cardio-embolism (CE), small-vessel occlusion (SVO), other determined aetiologies (OTH), and undetermined aetiologies (UND). Temporal trends in survival rates were examined using proportional-hazards survival modelling, adjusted for demography, prestroke risk factors, case mix variables, and processes of care. We carried out additional regression analyses to explore patterns in case-fatality rates (CFRs) at 30 days and 1 year and to explore whether these trends occurred at the expense of greater functional dependence (Barthel Index [BI] < 15) among survivors. A total of 3,128 patients with first-ever ISs were registered. The median age was 70.7 years; 50.9% were males; and 66.2% were white, 25.5% were black, and 8.3% were of other ethnic groups. Between 2000–2003 and 2012–2015, the adjusted overall mortality decreased by 24% (hazard ratio [HR] per year 0.976; 95% confidence interval [CI] 0.959–0.993). Mortality reductions were equally noted in both sexes and in the white and black populations but were only significant in CE strokes (HR per year 0.972; 95% CI 0.945‒0.998) and in patients aged ≥55 years (HR per year 0.975; 95% CI 0.959‒0.992). CFRs within 30 days and 1 year after an IS declined by 38% (rate ratio [RR] per year 0.962; 95% CI 0.941‒0.984) and 37% (RR per year 0.963; 95% CI 0.949‒0.976), respectively. Recent IS was independently associated with a 23% reduced risk of functional dependence at 3 months after onset (RR per year 0.983; 95% CI 0.968–0.998; p = 0.002 for trend). The study is limited by small number of events in certain subgroups (e.g., LAA), which could have led to insufficient power to detect significant trends.

Conclusions
Both mortality and 3-month functional dependence after IS decreased by an annual average of around 2.4% and 1.7%, respectively, during 2000‒2015. Such reductions were particularly evident in strokes of CE origins and in those aged ≥55 years.

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