A protocol for investigation of the effects of outdoor air pollution on stroke incidence, phenotypes and survival using the South London Stroke Register

• Published in: International journal of health geographics 2006-03, Vol.5 (1), p.10-10, Article 10
• Main Authors: Maheswaran, Ravi, Pearson, Tim, Campbell, Michael J, Haining, Robert P, McLeod, Cameron W, Smeeton, Nigel, Wolfe, Charles D A
• Format: Article
• Language: English
• Subjects: Adult; Aged; Air Pollution - adverse effects; Air Pollution - analysis; Case-Control Studies; Cohort Studies; Female; Humans; Incidence; London - epidemiology; Male; Methodology; Middle Aged; Registries; Risk Factors; Sex Factors; Socioeconomic Factors; Stroke - epidemiology; Stroke - etiology; Stroke - mortality
• ISSN: 1476-072X; 1476-072X
• DOI: 10.1186/1476-072X-5-10

Stroke is a major cause of death and disability. About 5.3 million people die every year from stroke worldwide with over 9 million people surviving at any one time after suffering a stroke. About 1 in 4 men and 1 in 5 women aged 45 years will suffer a stroke if they live to their 85th year. It is estimated that by 2023 there will be an absolute increase in the number of people experiencing a first ever stroke of about 30% compared with 1983. In the UK, stroke is the third commonest cause of death and the most common cause of adult physical disability and consumes 5% of the health and social services budget. Stroke is assuming strategic public health importance because of increased awareness in society, an ageing population and emerging new treatments. It is an NHS health service and research priority, being identified as a target in Our Healthier Nation and the NSF for Older People for prevention and risk factor control and in the NHS Plan as a disease requiring intermediate care planning and reduction in inequalities of care. Whilst a number of risk factors for stroke are well known (e.g. increasing age, ethnicity, socioeconomic deprivation, hypertension), the potential importance of outdoor air pollution as a modifiable risk factor is much less well recognised. This is because studies to date are inconclusive or have methodological limitations. In Sheffield, we estimated that 11% of stroke deaths may be linked to current levels of outdoor air pollution and this high figure is explained by the fact that so many people are exposed to air pollution.We plan to study the effects of outdoor air pollution on stroke using a series of epidemiological (i.e. population based) studies. The purpose of this project is: to examine if short term increases in pollution can trigger a stroke in susceptible individuals, to investigate if the occurrence of stroke is higher amongst people living in more polluted areas (which would be explained by a combination of exposure to short term increases and longer term exposure to higher pollution levels), and to see if people living in more polluted areas have reduced survival following their stroke. We will use geographical information systems, robust statistical methods and powerful grid computing facilities to link and analyse the data. The datasets we will use are the South London Stroke Register database, daily monitored pollution data from national monitoring networks and modelled pollution data for London from the Greater Lon