Effect of Exhaust- and Nonexhaust-Related Components of Particulate Matter on Long-Term Survival After Stroke.
Outdoor air pollution represents a potentially modifiable risk factor for stroke. We examined the link between ambient pollution and mortality up to 5 years poststroke, especially for pollutants associated with vehicle exhaust.



Data from the South London Stroke Register, a population-based register covering an urban, multiethnic population, were used. Hazard ratios (HR) for a 1 interquartile range increase in particulate matter <2.5 µm diameter (PM2.5) and PM <10 µm (PM10) were estimated poststroke using Cox regression, overall and broken down into exhaust and nonexhaust components. Analysis was stratified for ischemic and hemorrhagic strokes and was further broken down by Oxford Community Stroke Project classification.



The hazard of death associated with PM2.5up to 5 years after stroke was significantly elevated (P=0.006) for all strokes (HR=1.28; 95% confidence interval [CI], 1.08-1.53) and ischemic strokes (HR, 1.32; 95% CI, 1.08-1.62). Within ischemic subtypes, PM2.5pollution increased mortality risk for total anterior circulation infarcts by 2-fold (HR, 2.01; 95% CI, 1.17-3.48; P=0.012) and by 78% for lacunar infarcts (HR, 1.78; 95% CI, 1.18-2.66; P=0.006). PM10pollution was associated with 45% increased mortality risk for lacunar infarct strokes (HR, 1.45; 95% CI, 1.06-2.00; P=0.022). Separating PM2.5and PM10into exhaust and nonexhaust components did not show increased mortality.



Exposure to certain outdoor PM pollution, particularly PM2.5, increased mortality risk poststroke up to 5 years after the initial stroke.
From the Division of Health and Social Care Research (A.D., S.C., U.H., C.D.A.W.), Analytical and Environmental Sciences Division and MRC-PHE Centre for Environment and Health (B.B., S.D.B., F.J.K.), King's College London, United Kingdom; NIHR Biomedical Research Centre, Guy's & St. Thomas' NHS Foundation Trust and King's College London, United Kingdom (U.H., B.B., F.J.K., C.D.A.W.); and National Institute of Health Research Collaboration for Leadership in Applied Health Research and Care (CLAHRC) South London, United Kingdom (C.D.A.W.). anita.desikan@kcl.ac.uk.
Anita
A
Desikan
From the Division of Health and Social Care Research (A.D., S.C., U.H., C.D.A.W.), Analytical and Environmental Sciences Division and MRC-PHE Centre for Environment and Health (B.B., S.D.B., F.J.K.), King's College London, United Kingdom; NIHR Biomedical Research Centre, Guy's & St. Thomas' NHS Foundation Trust and King's College London, United Kingdom (U.H., B.B., F.J.K., C.D.A.W.); and National Institute of Health Research Collaboration for Leadership in Applied Health Research and Care (CLAHRC) South London, United Kingdom (C.D.A.W.).
Siobhan
S
Crichton
From the Division of Health and Social Care Research (A.D., S.C., U.H., C.D.A.W.), Analytical and Environmental Sciences Division and MRC-PHE Centre for Environment and Health (B.B., S.D.B., F.J.K.), King's College London, United Kingdom; NIHR Biomedical Research Centre, Guy's & St. Thomas' NHS Foundation Trust and King's College London, United Kingdom (U.H., B.B., F.J.K., C.D.A.W.); and National Institute of Health Research Collaboration for Leadership in Applied Health Research and Care (CLAHRC) South London, United Kingdom (C.D.A.W.).
Uy
U
Hoang
From the Division of Health and Social Care Research (A.D., S.C., U.H., C.D.A.W.), Analytical and Environmental Sciences Division and MRC-PHE Centre for Environment and Health (B.B., S.D.B., F.J.K.), King's College London, United Kingdom; NIHR Biomedical Research Centre, Guy's & St. Thomas' NHS Foundation Trust and King's College London, United Kingdom (U.H., B.B., F.J.K., C.D.A.W.); and National Institute of Health Research Collaboration for Leadership in Applied Health Research and Care (CLAHRC) South London, United Kingdom (C.D.A.W.).
Benjamin
B
Barratt
From the Division of Health and Social Care Research (A.D., S.C., U.H., C.D.A.W.), Analytical and Environmental Sciences Division and MRC-PHE Centre for Environment and Health (B.B., S.D.B., F.J.K.), King's College London, United Kingdom; NIHR Biomedical Research Centre, Guy's & St. Thomas' NHS Foundation Trust and King's College London, United Kingdom (U.H., B.B., F.J.K., C.D.A.W.); and National Institute of Health Research Collaboration for Leadership in Applied Health Research and Care (CLAHRC) South London, United Kingdom (C.D.A.W.).
Sean D
SD
Beevers
From the Division of Health and Social Care Research (A.D., S.C., U.H., C.D.A.W.), Analytical and Environmental Sciences Division and MRC-PHE Centre for Environment and Health (B.B., S.D.B., F.J.K.), King's College London, United Kingdom; NIHR Biomedical Research Centre, Guy's & St. Thomas' NHS Foundation Trust and King's College London, United Kingdom (U.H., B.B., F.J.K., C.D.A.W.); and National Institute of Health Research Collaboration for Leadership in Applied Health Research and Care (CLAHRC) South London, United Kingdom (C.D.A.W.).
Frank J
FJ
Kelly
From the Division of Health and Social Care Research (A.D., S.C., U.H., C.D.A.W.), Analytical and Environmental Sciences Division and MRC-PHE Centre for Environment and Health (B.B., S.D.B., F.J.K.), King's College London, United Kingdom; NIHR Biomedical Research Centre, Guy's & St. Thomas' NHS Foundation Trust and King's College London, United Kingdom (U.H., B.B., F.J.K., C.D.A.W.); and National Institute of Health Research Collaboration for Leadership in Applied Health Research and Care (CLAHRC) South London, United Kingdom (C.D.A.W.).
Charles D A
CD
Wolfe
D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008131:London / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter / Q000009:adverse effects*; D012042:Registries; D012307:Risk Factors; D020521:Stroke / Q000401:mortality*
D000393:Air Pollutants; D052638:Particulate Matter
air pollution; mortality; particulate matter; stroke; survival analysis