Relationship between Asian dust and ischemic stroke: A time-stratified case-crossover study

Background and Purpose-Particulate matter is increasingly recognized as a cause of human diseases, including cardiovascular diseases. However, the association between Asian dust (AD), a windblown sand dust originating from mineral soil in the deserts of China and Mongolia, and the incidence of cardiovascular diseases is unclear. The aim of the present study was to elucidate whether AD is associated with the incidence of ischemic stroke. Methods-This study investigated the onset time of 7429 consecutive patients with ischemic stroke who were admitted to seven stroke centers in Fukuoka, Japan, between June 1999 and March 2010. Meteorologic variables and air pollutants, including AD and suspended particulate matters, were investigated during the identical period. A time-stratified case-crossover study was conducted to assess the association between AD and stroke incidence using a conditional logistic regression analysis. Results-Although AD was not significantly associated with the overall incidence of ischemic stroke, there was a relationship specific to the stroke subtypes. AD was significantly associated with the incidence of atherothrombotic brain infarction after adjusting for expected confounders, including meteorologic variables and other air pollutants. No association was detected in other types of ischemic stroke. Conclusion-These data suggest that AD does not increase the overall incidence of ischemic stroke, but it is specifically associated with the risk of atherothrombotic brain infarction.