Effect of Seasonal and Monthly Variation in Weather and Air Pollution Factors on Stroke Incidence in Seoul, Korea

Abstract

Background and Purpose-The purpose of the present study was to determine whether seasonal and monthly variations in stroke incidence exist and whether they are related to meteorologic and air pollution parameters under similar weather and environmental conditions in selected areas of Seongdong district, Seoul, South Korea. Methods-From January 1, 2004, to December 31, 2013, 3001 consecutive stroke events were registered in residents of selected areas of Seongdong district, Seoul, South Korea. The authors calculated the stroke attack rate per 100 000 people per month and the relative risk of stroke incidence associated with meteorologic and air pollution parameters. We also analyzed odds ratios with a 95% confidence interval for seasonal and monthly stroke incidence. Results-The incidence of stroke in September was significantly higher (odds ratio, 1.233; 95% confidence interval, 1.042-1.468) compared with January. The seasonal ischemic stroke incidence in summer (odds ratio, 1.183; 95% confidence interval, 1.056-1.345) was significantly higher than in winter, whereas the seasonal incidence of intracerebral hemorrhage relative to winter was not significant. The mean temperature was positively correlated with ischemic stroke (relative risk, 1.006; P=0.003), and nitrogen dioxide (relative risk, 1.262; P=0.001) showed a strong positive correlation with intracerebral hemorrhage incidence among the older age group. Conclusions-We demonstrated distinct patterns of seasonal and monthly variation in the incidence of stroke and its subtypes through consideration of the meteorologic and air pollution parameters. We therefore expect that these findings may enhance our understanding of the relationships between stroke and weather and pollutants.

Relationship between weather conditions and admissions for ischemic stroke and subarachnoid hemorrhage

“…The number of strokes increased with temperature and daily temperature range, associations with low pressure and falling pressure were observed which is in line with our observations since we also reported that stroke cases are predicted by daily lowest - and also highest - air pressure and highest air temperature. Han et al recently demonstrated distinct patterns of seasonal and monthly variation in the stroke incidence and its subtypes through consideration of the meteorological and air pollution parameters in nine year term in Seoul, South Korea (3). They found that the mean temperature was positively correlated with stroke which is in line with our findings (3).…”

“…Moreover, circadian variation has been also shown to have an important effect (2). Recently, more attention has been oriented toward the effect of weather conditions on stroke admissions (3-5). However, evidence of the impact of air temperature and pressure and the extreme weather conditions (tropical storms, hurricanes) on cerebrovascular morbidity is still quite limited and controversial.…”

Temporal Variations of Stroke Occurence

“…Constantly informing the public of the need to seek medical help promptly after stroke onset and using an ambulance and direct transportation to the hospital. Also it is necessary to have more effective in-hospital organization in order to improve availability of effective acute treatment options to stroke patients (14).…”

“…According to some studies stroke occurence was more frequent on weekdays than on weekends (6), and usually on Mondays (7,9,14). Some studies found no difference in the frequency of occuring of all stroke types by days of the week (2), some of them found no difference for ICH and SAH (4, 7).…”

“…Some studies showed that stroke occurence was more frequent on weekdays than on weekends (6,7,9,14). Some studies showed the highest incidence of IS in January and the lowest incidence for women in August, and for men in June (15).…”