Air pollution and the incidence of ischaemic and haemorrhagic stroke in the South London Stroke Register: a case-cross-over analysis

TitleAir pollution and the incidence of ischaemic and haemorrhagic stroke in the South London Stroke Register: a case-cross-over analysis
Publication TypeJournal Article
Year of Publication2017
AuthorsButland B.K, Atkinson R.W, Crichton S., Barratt B., Beevers S., Spiridou A., Hoang U., Kelly F.J, Wolfe C.D
JournalJournal of Epidemiology and Community Health
Date PublishedJul
ISBN Number0143-005x
Accession Number28408613
KeywordsAged, Air Pollutants/*adverse effects/*analysis, Air Pollution, Cross-Over Studies, Environmental epidemiology, Environmental Exposure/*adverse effects/*analysis, Environmental Monitoring/methods, Female, from NIHR during the conduct of the study., Humans, Incidence, London/epidemiology, Male, Middle Aged, personal fees from COMEAP outside the submitted work. FJK and AS report grants, Registries, Risk Factors, RWA reports grants from King's College London during the conduct of the study and, Southern Energy. Her work on this project was funded by King's College London., Stroke, Stroke/*epidemiology, Weather

BACKGROUND: Few European studies investigating associations between short-term exposure to air pollution and incident stroke have considered stroke subtypes. Using information from the South London Stroke Register for 2005-2012, we investigated associations between daily concentrations of gaseous and particulate air pollutants and incident stroke subtypes in an ethnically diverse area of London, UK. METHODS: Modelled daily pollutant concentrations based on a combination of measurements and dispersion modelling were linked at postcode level to incident stroke events stratified by haemorrhagic and ischaemic subtypes. The data were analysed using a time-stratified case-cross-over approach. Conditional logistic regression models included natural cubic splines for daily mean temperature and daily mean relative humidity, a binary term for public holidays and a sine-cosine annual cycle. Of primary interest were same day mean concentrations of particulate matter <2.5 and <10 microm in diameter (PM2.5, PM10), ozone (O3), nitrogen dioxide (NO2) and NO2+nitrogen oxide (NOX). RESULTS: Our analysis was based on 1758 incident strokes (1311 were ischaemic and 256 were haemorrhagic). We found no evidence of an association between all stroke or ischaemic stroke and same day exposure to PM2.5, PM10, O3, NO2 or NOX. For haemorrhagic stroke, we found a negative association with PM10 suggestive of a 14.6% (95% CI 0.7% to 26.5%) fall in risk per 10 microg/m(3) increase in pollutant. CONCLUSIONS: Using data from the South London Stroke Register, we found no evidence of a positive association between outdoor air pollution and incident stroke or its subtypes. These results, though in contrast to recent meta-analyses, are not inconsistent with the mixed findings of other UK studies.

Short TitleJ. Epidemiol. Community HealthJ. Epidemiol. Community Health
Alternate JournalJournal of epidemiology and community health