Diss. Lund : Lund University. Faculty of Medicine. Doctoral Dissertation Series 2009:120, 2009

Cardiovascular disease (CVD) is a class of disorders affecting the heart and blood vessels. CVD is the most common cause of death throughout the world. One of the most common diseases among CVD is cerebrovascular disease, which is a disease of the blood vessels supplying the brain: stroke being the most common disorder. Stroke is the single somatic disease that requires the largest number of days of care at Swedish hospitals and the total cost to society has been estimated to be about 0.5% of the Swedish GDP. Beside the traditional risk factors (smoking, hypertension, diabetes mellitus, atrial fibrillation, physical inactivity and poor socio-economic conditions), air pollution is becoming an acknowledged risk factor for stroke, especially regarding its acute effects. Chronic effects of air pollution in relation to stroke are less well documented than acute effects, possibly due to the methodological challenges of assessing long-term health effects of air pollution. Some of these challenges can be overcome by using so called two-phase methods, where registry-data for a large sample is combined with more detailed data for a subsample, but further studies are required to determine the extent to which they can be used and their limitations. The implementation of measures to improve outdoor air quality and reduce the concentrations of pollutants has led to decreased mortality (Clancy et al. 2002; Laden et al. 2006). Given the considerable health burden caused by stroke and the fact that air pollution affects the total population, it is important from a public health perspective to investigate the extent of the association between air pollution and stroke in a setting where pollution levels are generally lower than present day air quality guidelines. The specific aims of this thesis were: 1. to investigate the association between long-term exposure (chronic effects) to air pollution and the incidence of stroke in Scania (southernmost part of Sweden) (Papers III & V); 2. to investigate the association between short-term exposure (acute effects) to air pollution and the incidence of stroke in Scania (Paper IV); 3. to elucidate a possible association between socio-economic status and air pollution in Scania, and to investigate whether such associations depend on geographic level or type of socio-economic index (Paper I); 4. to generalise a specific two-phase method so as to be applicable in settings with arealevel polytomous exposure variables obtained from an exposure database (Paper II); 5. to examine the strengths and limitations of various two-phase methods (Paper II and thesis frame); 6. to compare two different approaches to the analysis of acute exposure effects (Paper IV and thesis frame). Alternative URL: http://www.avhandlingar.se/avhandling/e2fe174956/